THE YOUNG STELLAR POPULATION OF LYNDS 1340. AN INFRARED VIEW

M. Kun; G. Wolf-Chase; A. Moór; D. Apai; Z. Balog; J. O’Linger-Luscusk; G. H. Moriarty-Schieven

doi:10.3847/0067-0049/224/2/22

1. INTRODUCTION

The star-forming history of molecular clouds and the early evolution of stars and protoplanetary disks depend on the environment (e.g., Zhang & Tan 2015). Since most stars form in a clustered environment, it is important to assess how this environment influences the timescales and efficiencies of star formation and the evolution of protoplanetary disks around young stars. The impact of feedback from the newborn high-mass (spectral types O and early B) stars on the evolution of their natal cloud and the properties of the emergent star clusters are studied in detail by, e.g., Dib et al. (2013). Important basic properties of massive star-forming regions (MSFRs) have emerged from the MYStIX project (Feigelson et al. 2013). The effect of intermediate-mass stars (i.e., spectral types mid- to late B and early A) on the ambient medium in which they are forming has attracted less interest. There are clouds with structure and star-forming properties intermediate between the two extremes of isolated star formation (e.g., Taurus, Cepheus flare) and the rich clusters found around very massive stars (e.g., Orion). In these regions, young stars are concentrated in small clusters, whose highest-mass member is usually a B-type star. Well-known nearby examples of this type are IC 348, NGC 7023, and NGC 7129. The role of this intermediate mode of star formation in shaping the present appearance of our Galaxy is not well known. Adams & Myers (2001) suggested that most of the Galactic stellar content might have originated from clusters containing fewer than some 100 members. A clearer observational picture of the intermediate mode is essential to our understanding of the star formation process.

Arvidsson et al. (2010) identified a sample of 50 intermediate-mass star-forming regions (IMSFRs), based on IRAS colors, Spitzer images, and millimeter continuum and ¹³CO maps. They found typical luminosities of ∼10⁴ L_☉, diameters of ∼1 pc, and associated molecular clumps of mass 10³ M_☉. Recently, Lundquist et al. (2014) presented an all-sky sample of 984 candidate Galactic IMSFRs and studied in detail four of the candidates, confirming that these regions contain loose clusters of low- and intermediate-mass stars. The ¹³CO survey of Lundquist et al. (2015) has shown that molecular line width and column density correlate with the infrared luminosity of the region. Several targets of the Spitzer survey of young stellar clusters within 1 kpc of the Sun (Gutermuth et al. 2009) belong to this class of SFRs. Evidence for the impact of intermediate-mass stars on their interstellar environment comes from Arce et al. (2011), who identified a great number of bubble-like structures in Perseus, most of them around intermediate-mass stars. Examination of these SFRs is particularly important because it helps us understand the relationship between cloud structure and star-forming mode.

The first large-scale study of Lynds 1340 (Kun et al. 1994, hereafter Paper I), including an objective prism survey for Hα emission, low-resolution ¹²CO, ¹³CO, and C¹⁸O maps, and IRAS data analysis, suggests that this cloud is an IMSFR, containing a few mid-B, A, and early F-type stars associated with reflection nebulosities (Dorschner & Gürtler 1968). The ¹³CO maps revealed three clumps: L1340 A, L1340 B, and L1340 C. Ten dense cores have been identified in L1340 through a large-scale NH₃ survey (Kun et al. 2003, hereafter Paper II), with masses and kinetic temperatures halfway between the values obtained for the ammonia cores in Taurus and Orion. Thirteen Hα emission objects were identified in Paper I, and 14, which were concentrated in the small nebulous cluster RNO 7 (Cohen 1980), were identified by Magakian et al. (2003). Herbig–Haro objects and their driving sources are reported in Kumar et al. (2003) and Magakian et al. (2003). An overview of the region is presented in Kun (2008). Our recent paper (Kun et al. 2015, hereafter Paper III) reports on 11 candidate intermediate-mass (2–5 M_☉) members and 58 new candidate T Tauri stars in L1340 and presents a revised distance of 825 pc.

Whereas most of the cluster-forming molecular clouds of our Galactic neighborhood, including those studied by Arvidsson et al. (2010) and Lundquist et al. (2014), are parts of giant SFRs, which also contain high-mass stars (e.g., Ridge et al. 2003), Lynds 1340 is an isolated molecular cloud of some 3700 M_☉ at a Galactic latitude of b ≈ 11 fdg 5, corresponding to some 160 pc distance above the Galactic plane. To explore the nature of interstellar processes, leading to star formation in this environment, the cloud structure and the young stellar population have to be mapped. In this paper we identify the young stellar object (YSO) population of L1340 based on Spitzer and WISE mid-infrared data, as well as on high angular resolution near-infrared imaging data of the embedded RNO 7 cluster. The goals of our studies are as follows: (i) determine the properties of star formation in this cloud, such as surface distribution, mass and age spread, accretion and disk properties of young stars, and efficiency of star formation; (ii) explore possible feedback from intermediate-mass stars; and (iii) integrate this cloud into the picture of star formation of our 1 kpc Galactic environment. We describe the available data and analysis in Section 2. The results are presented and discussed in Sections 3–6. A short summary of the results is given in Section 7.

2. DATA

2.1. Spitzer Data

L1340 was observed by the Spitzer Space Telescope using Spitzer's Infrared Array Camera (IRAC; Fazio et al. 2004) on 2009 March 16 and the Multiband Imaging Photometer for Spitzer (MIPS; Rieke et al. 2004) on 2008 November 26 (Prog. ID: 50691, PI: G. Fazio). The IRAC observations covered ∼1 deg² in all four bands. Moreover, a small part of the cloud, centered on RNO 7, was observed in the four IRAC bands on 2006 September 24 (Prog. ID: 30734, PI: D. Figer). Figure 1 shows the areas of the Spitzer observations, overplotted on the DSS2 red image of the region. ¹³CO contours from Paper I are drawn to indicate the boundaries of the molecular cloud, and the L1340 A, L1340, and L1340 C clumps are marked. The centers of the 3.6 and 5.8 μm images are slightly displaced from those of the 4.5 and 8 μm images; therefore, part of the clump L1340 C is outside of the 4.5 and 8 μm maps. Moreover, the 24 and 70 μm images do not cover the southern half of L1340 A. The data of the four IRAC and MIPS 24 μm bands were processed by the Spitzer Science Center (SSC), and the resulting Super Mosaics and Source List are available at http://irsa.ipac.caltech.edu/data/SPITZER/Enhanced/SEIP/. We selected candidate YSOs from the Spitzer Enhanced Imaging Products (SEIP) Source List, containing 19,745 point sources in the target field.

**Figure 1.** Outlines of the *Spitzer* IRAC (blue solid line: 3.6 and 5.8 μm; red dot-dashed line: 4.5 and 8.0 μm), MIPS 24 μm (orange triple-dot-dashed line), and MIPS 70 μm (black dot-dashed line) observations, overplotted on the DSS2 red image of the region, 1 square degree in area. Both the lowest contour and the increment of the overlaid ¹³CO integrated intensity map are 0.5 K km s⁻¹.
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We followed the methods described in Gutermuth et al. (2009) for removing probable extragalactic, stellar, and interstellar sources and selecting candidate YSOs based on color indices. We identified 98 candidate YSOs detected in each of the four IRAC bands (Phase 1 criteria of Gutermuth et al. 2009). Phase 2 criteria, based on Two Micron All Sky Survey (2MASS), 3.6 and 4.5 μm data, resulted in 44 new YSO candidates. Based on their high MIPS 24 μm fluxes and very red [24]–[IRAC_i] color (Phase 3 criteria), we identified 46 additional sources that were missing one or more IRAC band data. Four additional sources obeyed the criteria [4.5]–[8.0] > 0.5 and [8.0] < 14 − ([4.5]–[8.0]), set by Harvey et al. (2006). A sizeable area of the cloud was observed only at 3.6 and 5.8 μm. We regarded sources, located in this area and having [3.6]–[5.8] > 0.50, as candidate YSOs. Thirteen new objects were selected by this criterion. Most of them have associated Sloan Digital Sky Survey (SDSS), 2MASS, and/or WISE data, which help confirm their candidate YSO nature. We also subjected the SEIP Source List of L1340 to the criteria established by Kryukova et al. (2012) for selecting protostars. Of the 116 sources meeting the color criteria, there are 19 not selected during the previous steps and located within the lowest significant C¹⁸O contours of the cloud clumps. These sources were also included in the candidate YSO list.

Owing to the strict quality requirements of the SEIP Source List, several sources might have been missed in one or more bands. Furthermore, the 70 μm data are not included in the SEIP database. Therefore, we checked the positions of the selected sources and performed photometry by the procedures described in Kun et al. (2014) to refill the missing flux data. Then we checked the 70 μm images at each source position and measured 70 μm fluxes. Figure 2 compares our photometry with the SEIP Source List data.

**Figure 2.** SEIP Source List fluxes of a sample of candidate YSOs plotted against those measured during the present work.
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2.2. High Angular Resolution Near-infrared Imaging

High angular resolution near-infrared images of two small regions of L1340 were obtained on 2002 October 24 in the JHK bands, using the near-infrared camera Omega-Cass, mounted on the 3.5 m telescope at the Calar Alto Observatory, Spain. Our targets were IRAS 02224+7227, the possible driving source of HH 487, and the compact, partly embedded cluster RNO 7, centered on IRAS 02236+7224. The results for IRAS 02224+7227 have been shown in Kun et al. (2014). Here we present the results for RNO 7.

Omega-Cass's detector was a Rockwell 1024 × 1024 pixel HAWAII array (HgCdTe detector + Si MOSFET nondestructive readout). The plate scale was 0 farcs 1 pixel^–1. RNO 7 was observed at four dithering positions around the nominal position of IRAS 02234+7224, and the observations consisted of two dither cycles, and each cycle with 120 s (4 × 30 s in J and H, 12 × 10 s in K) spent at each position. Thus, the total on-source integration time of a cycle was 480 s in each filter. Double Correlated Read (Reset-Read-Read) was applied.

The data were reduced in IRAF. Following the flat-field correction and bad pixel removal, the sky frame for each cycle was obtained by taking the minimum of the images at different dithering positions. This sky frame was subtracted from each individual image of a given cycle. Then the frames from a single cycle were combined into a mosaic image, and aperture photometry was performed on the reduced images. The instrumental magnitudes were transformed into the JHK_s system by using the 2MASS magnitudes of 17 stars within the field of view. Then, in order to search for possible close visual companions, the point-spread functions (PSFs) of the images were determined, and the scaled PSFs of the stars were subtracted from the images.

2.3. Supplementary Data

To classify the evolutionary status of the color-selected candidate YSOs and obtain as complete a picture of the SFR and its YSO population as possible, we supplemented the Spitzer data with photometric data available in public databases. The databases included in our study are as follows.

2MASS and AllWISE Data. The SEIP Source List contains WISE and 2MASS associations of the cataloged objects. WISE 22 μm fluxes exist for 24 Spitzer-selected candidate YSOs outside of the area of the 24 μm MIPS observations. We included these associations in the analysis, taking into account that, owing to the different angular resolutions, a few 2MASS/WISE sources are associated with more than one IRAC source. Furthermore, we searched the AllWISE Source Catalog (Wright et al. 2010) for YSOs, using the color and flux criteria established by Koenig et al. (2012) and Koenig & Leisawitz (2014). We identified eight new candidate YSOs, seven of which are located outside of the field of view of the Spitzer observations.

Akari FIS/IRC Data. Akari far-infrared all-sky survey images (Doi et al. 2015), tracing out the surface and temperature structure of the cold dust in the cloud region, are accessible at http://www.ir.isas.jaxa.jp/AKARI/Archive/Images/FISMAP/. We identified counterparts of nine candidate YSOs in the Akari/FIS Bright Source Catalog (Yamamura et al. 2010), containing point sources detected at 65, 90, 140, and 160 μm.

Submillimeter Data. Part of the molecular clump L1340 B was observed at 450 and 850 μm with the Submillimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. The outlines of the mapped area are shown in Figure 6 of Paper III. The 850 μm image and positions, sizes, and fluxes/upper limits of nine submillimeter sources can be found in the SCUBA Legacy Catalogs (Di Francesco et al. 2008), at http://www3.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/community/scubalegacy/. Four of them coincide in position with Spitzer sources.

Herschel Data for L1340 C. The Planck Galactic cold clump PGCC G130.38+11.26, associated with L1340 C, was included in the detailed Herschel study of cold clumps by Juvela et al. (2012). Far-infrared images, observed by the PACS instrument at 100 and 160 μm, as well as 250, 350, and 500 μm images observed by the SPIRE instrument, are available in the Herschel Science Archive (http://www.cosmos.esa.int/web/herschel/science-archive). We found far-infrared counterparts of 20 color-selected Spitzer sources in the PACS 100 and 160 μm images. We measured the fluxes of the sources on the level2.5 JScanam images, downloaded from the Herschel Science Archive (Galactic Cold Cores: A Herschel survey of the source populations revealed by Planck; PI: M. Juvela). The photometry was performed using the L3_multiplePointSourceAperturePhotometry.py, supplied in HIPE 14.0 RC4 (Herschel Interactive Processing Environment; Ott 2010). We used 6'' and 10'' apertures at 100 and 160 μm, respectively, with an annulus between 35'' and 45'' for determining the background. The aperture correction were calculated using the values given in Balog et al. (2014). The initial positions of the sources were taken from the SEIP Source List and were refined using a two-dimensional Gaussian during the photometry.

SDSS Data. SDSS ugriz magnitudes are available for each star brighter than some 25 mag in each band within the whole area of L1340 (see Paper III). We searched for counterparts of our candidate YSOs in the SDSS Data Release 9 (Ahn et al. 2012) within 1'' of the SEIP Source List position. We transformed the SDSS magnitudes of the optical counterparts into the Johnson–Cousins UBVR_CI_C system, using the equations given in Ivezić et al. (2007; for BVR_CI_C) and Jordi et al. (2006; for U). We found optical counterparts for 149 of the 155 Class II Spitzer sources, and for 8 of the 26 flat spectral energy distribution (SED) sources (see Section 4.1).

3. INFRARED APPEARANCE OF L1340: THE SWAN NEBULA

The extended infrared emission reveals the surface distribution of various components of the cloud. Cold (T_kin ∼ 10–20 K), big (r ≳ 0.1 μm) dust grains radiate in the far-infrared, whereas extended mid-infrared emission traces out very small grains and excited PAH molecules. Heating and shocks from embedded YSOs also appear in the infrared images of a molecular cloud.

Figure 3 shows a three-color view of L1340, composed of the WISE 4.6 μm (blue), 12 μm (green), and 22 μm (red) images. Striking features of this image are the bright, extended 12 μm radiation, indicative of PAH emission excited by B- and A-type stars, and small groups of 22 μm sources, associated with the three cloud clumps. The shape of the brightest part of the diffuse 12 μm emission, located slightly northwest of the image center and associated with the clump L1340 B, suggests the Swan Nebula label.

fdg — **Figure 3.** *WISE* 4.6 μm (blue), 12 μm (green), and 22 μm (red) composite image of L1340. The size of the image is 1 square degree and is centered on R.A.(J2000) = 37625, decl.(J2000) = +72933. Small groups of 22 μm sources point to the three star-forming clumps of L1340. The extended 12 μm emission (the Swan Nebula) is excited by the B- and A-type stars associated with L1340 B. The annotated objects are the most striking signposts of low-mass star formation: IRAS 02224+7227 is an FUor-like star (Kun et al. 2014); IRAS 02249+7230 is a protostellar source exciting HH 489; RNO 7, RNO 8, and RNO 9 are nebulous, partially embedded stellar groups (Cohen 1980); and V1180 Cas is an eruptive star (Kun et al. 2011).
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Figure 4 is a composite of the 5.8 μm IRAC (blue), 24 μm MIPS (green), and 70 μm MIPS (red) images. The image reveals an extended 70 μm structure associated with RNO 8, diffuse 24 μm emission that delineates the Swan Nebula, a bluish (5.8 μm) glowing around the B-type stars, and a variety of far-infrared point sources.

To reveal further details of the diffuse infrared emission of L1340, we present three-color images of the clumps L1340 A, L1340 B, and L1340 C in Figures 5–7, respectively. Figure 5 is composed of IRAC 3.6 μm (blue), 4.5 μm (green), and 8.0 μm (red) Super Mosaic images of L1340 A (much of this clump is outside of the MIPS images). Conspicuous features of the image are a diffuse 8 μm emission around the A0-type star SDSS9 022738.01+723826.8 (Paper III), the nebulous RNO 7 cluster, and HH 488, stretching from NW toward SE near the southern boundary of the image. Figure 6 is composed of the 3.6 μm (blue), 8.0 μm (green), and 24 μm (red) images of the most massive clump L1340 B. The wispy structure of the Swan Nebula, suggesting a swirling gas cloud, becomes apparent in this image. A bow-shock-like feature can be seen around the star SDSS9 J023049.80+730110.2, demonstrating supersonic motion of the gas with respect to the A2-type, young intermediate-mass star (Paper III). The extended infrared emission from the smallest clump, L1340 C, shows up in the Herschel images, tracers of very cold dust. Figure 7, composed of the 3.6 μm IRAC (blue), 24 μm MIPS (green), and 250 μm SPIRE (red) images of the central 12' × 12' area of L1340 C, reveals a complex network of filamentary dust formations.

**Figure 5.** Three-color image of the cloud clump L1340 A, composed of *Spitzer* IRAC 3.6 μm (blue), 5.8 μm (green), and 8.0 μm (red) images. The size of the image is about 156 × 12'. The arrows point to the positions of the FUor-like YSO IRAS 02224+7227, the A0-type star SDSS9 J022738.01+723826.8, associated with extended 8 μm emission, the protostar IRAS 02249+7230, and the RNO 7 cluster.
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farcm — **Figure 5.** Three-color image of the cloud clump L1340 A, composed of *Spitzer* IRAC 3.6 μm (blue), 5.8 μm (green), and 8.0 μm (red) images. The size of the image is about 156 × 12'. The arrows point to the positions of the FUor-like YSO IRAS 02224+7227, the A0-type star SDSS9 J022738.01+723826.8, associated with extended 8 μm emission, the protostar IRAS 02249+7230, and the RNO 7 cluster.
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**Figure 6.** Three-color image of L1340 B, the Swan Nebula, composed of *Spitzer* IRAC 4.5 μm (blue), 8.0 μm (green), and MIPS 24 μm (red) images.
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**Figure 7.** Three-color image of the clump L1340 C, composed of *Spitzer* IRAC 3.6 μm (blue), MIPS 24 μm (green), and *Herschel* SPIRE 250 μm (red) images.
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The Akari Wide-L band image, centered on 140 μm, is displayed in Figure 8, with the contours of the visual extinction (Paper III) overplotted. The figure indicates that both the 140 μm emission and the visual extinction trace the same component of the cloud. The lowest contour at A_V = 1.0 mag largely follows the 40–50 MJy sr⁻¹ level of the far-infrared emission. At a few positions, heated by embedded YSOs, the strong 140 μm emission is not associated with high extinction.

4. YSOs IN L1340

4.1. Spitzer Sources

4.1.1. SED-based Classification

We classified the candidate YSOs, selected by the color criteria described in Section 2.1, based on the slope of their SEDs, $\alpha =d\mathrm{log}(\lambda F(\lambda ))/d\mathrm{log}\lambda$ . We derived α for both the K_s −24 μm and the 3.6–8.0 μm intervals (for 3.6–5.8 μm when 8 μm observations were missing). We used the WISE 22 μm data when 24 μm MIPS data were missing. According to the canonical classification scheme (Lada 1991; Greene et al. 1994), protostellar objects embedded in an envelope have α(2–24) > 0.3, whereas α(2–24) < −0.3 for pre-main-sequence stars surrounded by accretion disks. Flat SED sources with −0.3 ≤ α(2.0–24.0) ≤ 0.3 represent the transition between the protostellar and pre-main-sequence evolutionary phases. We classified 155 Class II, 45 Class I, and 25 Flat SED sources. We detected a further Class I/Class 0 source in the 70 μm MIPS image at 02^h29^m5690, +73°02'17 farcs 0. This source is undetectable at shorter wavelengths and coincides in position with an Akari FIS source and with a submillimeter source.

4.1.2. Estimating Foreground Extinction

Since the classification based on observed spectral slopes is biased by the extinction of the sources, we estimated the foreground extinctions of the candidate YSOs and then reclassified them according to the extinction-corrected SED slopes. Foreground extinctions of Class I and Flat SED sources were estimated using the extinction map, derived from SDSS star counts in Paper III. We adopted the pixel value of the extinction map at the position of the source as the foreground extinction of an embedded source. On the one hand, the extinction obtained in this manner is an upper limit, since the sources may be situated at any depth within the dusty medium. On the other hand, small-scale, high-extinction cores, missed by the extinction mapping, may be present around embedded sources. For the Class II sources we invoked SDSS and 2MASS counterparts. We compared the optical and near-infrared side (from the B to the J band) of the SED with a grid of reddened photospheres, following the method described in Paper III, and thus estimated the spectral type and extinction of the central star. Based on the slopes of the extinction-corrected SEDs, two sources, classified originally as Class I, moved into the Flat class, and one Flat SED source moved into the Class II sample. Tables 1–3 list the SSTSL2 identifiers and Spitzer fluxes of the Class 0/I, Flat SED, and Class II sources of L1340, respectively.

Table 1. SEIP SSTSL2 Fluxes and Uncertainties of Class 0/I Sources in L1340

No.	SSTSL2	F_3.6	F_4.5	F_5.8	F_8.0	F₂₄	F₇₀^a
		(mJy)	(mJy)	(mJy)	(mJy)	(mJy)	(mJy)
1	022756.91+730354.4	1.915 ± 0.005	3.782 ± 0.007	5.412 ± 0.016	6.104 ± 0.013	73.620 ± 0.164	828.038 ± 58.375
2	022800.65+730415.2	14.510 ± 0.014	25.430 ± 0.018	40.200 ± 0.044	67.940 ± 0.035	289.700 ± 0.263	404.928 ± 28.732
3	022808.60+725904.5	1.774 ± 0.005	2.873 ± 0.007	2.982 ± 0.013	1.888 ± 0.010	1.775 ± 0.132	596.200 ± 16.900
4	022818.51+723506.2	1.586 ± 0.004	6.086 ± 0.023	8.608 ± 0.020	9.509 ± 0.010	⋯	⋯
5	022820.81+723500.5	0.251 ± 0.001	2.019 ± 0.015	4.189 ± 0.014	8.067 ± 0.025	⋯	⋯
6	022825.07+730945.6	0.150 ± 0.002	0.179 ± 0.002	0.197 ± 0.007	0.842 ± 0.011	22.590 ± 0.135	43.500 ± 11.100
7	022842.57+723544.3	11.560 ± 0.010	19.330 ± 0.036	27.290 ± 0.034	28.610 ± 0.026	⋯	⋯
8	022844.40+723533.5	3.473 ± 0.005	4.359 ± 0.024	7.668 ± 0.019	7.259 ± 0.018	⋯	⋯
9	022844.71+730308.5	0.110 ± 0.002	0.135 ± 0.002	0.155 ± 0.007	0.284 ± 0.012	0.935 ± 0.121	⋯
10	022849.44+723731.6	0.035 ± 0.001	0.079 ± 0.002	0.105 ± 0.005	<0.023	<0.491	⋯
11	022855.69+731333.1	0.039 ± 0.001	0.063 ± 0.002	0.075 ± 0.006	0.083 ± 0.008	0.858 ± 0.132	⋯
12	022856.61+730903.2	0.108 ± 0.002	0.146 ± 0.002	0.212 ± 0.006	0.337 ± 0.007	2.936 ± 0.135	⋯
13	022906.09+730210.5	0.022 ± 0.001	0.030 ± 0.002	0.039 ± 0.004	0.063 ± 0.008	0.657 ± 0.124	⋯
14	022914.62+730102.8	0.063 ± 0.001	0.081 ± 0.002	⋯	0.381 ± 0.007	1.270 ± 0.137	⋯
15	022918.25+724754.0	0.081 ± 0.001	0.097 ± 0.002	0.087 ± 0.006	0.074 ± 0.008	3.509 ± 0.127	64.600 ± 9.80
16	022931.98+725912.4	0.959 ± 0.003	1.755 ± 0.005	1.699 ± 0.010	1.159 ± 0.009	211.700 ± 0.218	1949.471 ± 136.77
17	022932.31+725503.2^b	0.226 ± 0.002	0.274 ± 0.002	0.419 ± 0.006	0.956 ± 0.009	5.341 ± 0.134	⋯
18	022943.01+724359.6	⋯	2.118 ± 0.005	3.482 ± 0.005	6.541 ± 0.015	<0.659	⋯
19	022943.64+724358.6	2.316 ± 0.004	7.394 ± 0.012	13.270 ± 0.024	19.350 ± 0.021	375.200 ± 0.250	2496.581 ± 175.06
20	022949.62+725326.1	0.238 ± 0.002	0.428 ± 0.003	0.622 ± 0.007	1.286 ± 0.010	53.000 ± 0.153	103.044 ± 7.602
21	022955.10+730309.1	1.703 ± 0.005	3.281 ± 0.008	6.332 ± 0.018	14.200 ± 0.018	58.580 ± 0.165	51.500 ± 21.000
22	022956.90+730217.0^c	⋯	⋯	⋯	⋯	⋯	262.0 ± 36.6
23	023022.78+730459.0	1.137 ± 0.004	1.790 ± 0.006	2.709 ± 0.012	3.747 ± 0.013	24.220 ± 0.155	69.852 ± 5.871
24	023030.42+725706.7	0.084 ± 0.001	0.108 ± 0.002	0.156 ± 0.005	0.293 ± 0.008	2.228 ± 0.126	⋯
25	023032.44+725918.0^b	79.412 ± 3.192	115.791 ± 4.498^a	215.566 ± 7.104	528.239 ± 18.993^a	2069.692 ± 82.791	1876.886 ± 132.659
26	023035.51+730828.2	0.227 ± 0.002	0.466 ± 0.003	0.753 ± 0.008	1.187 ± 0.010	3.066 ± 0.113	⋯
27	023042.36+730305.1	4.773 ± 0.009	13.510 ± 0.016	24.490 ± 0.034	28.800 ± 0.024	117.100 ± 0.180	484.031 ± 34.168
28	023127.34+724012.9	2.280 ± 0.072	5.119 ± 0.353	10.224 ± 0.313	15.729 ± 0.518	101.771 ± 4.074	663.806 ± 46.801
29	023134.23+725829.1	0.057 ± 0.001	0.090 ± 0.001	0.119 ± 0.005	0.075 ± 0.007	0.782 ± 0.119	⋯
30	023142.50+725740.4	0.049 ± 0.001	0.069 ± 0.002	0.076 ± 0.005	0.355 ± 0.010	0.808 ± 0.123	⋯
31	023146.58+723729.4	⋯	⋯	0.256 ± 0.006	⋯	3.952 ± 0.128	⋯
32	023203.42+724131.7	0.062 ± 0.001	0.177 ± 0.002	0.417 ± 0.008	0.930 ± 0.012	3.437 ± 0.112	⋯
33	023207.96+723759.3	0.784 ± 0.003	⋯	3.255 ± 0.013	⋯	26.570 ± 0.146	162.799 ± 11.629
34	023225.98+724020.1	⋯	⋯	9.834 ± 0.021	⋯	79.120 ± 0.163	626.957 ± 44.163
35	023226.35+723919.4	2.839 ± 0.005	⋯	1.752 ± 0.009	⋯	72.926 ± 1.888	375.855 ± 27.889
36	023227.64+723841.4^d	0.693 ± 0.022	⋯	0.847 ± 0.033	⋯	17.613 ± 0.715	378.511 ± 27.082
37	023232.00+723827.5	4.784 ± 0.006	⋯	13.880 ± 0.025	⋯	57.910 ± 0.124	343.451 ± 24.445
38	023237.90+723940.7	0.094 ± 0.001	⋯	0.543 ± 0.007	⋯	<0.361	⋯
39	023248.83+724635.4	0.305 ± 0.002	0.251 ± 0.002	0.226 ± 0.007	2.142 ± 0.009	3.936 ± 0.138	⋯
40	023256.14+724605.3	1.338 ± 0.003	1.697 ± 0.004	1.639 ± 0.010	1.428 ± 0.008	57.310 ± 0.147	847.044 ± 59.580
41	023302.41+724331.2	5.987 ± 0.007	14.790 ± 0.012	27.930 ± 0.035	57.890 ± 0.033	530.100 ± 0.265	2281.543 ± 160.168
42	023330.92+724800.3	0.162 ± 0.002	0.248 ± 0.002	0.246 ± 0.007	0.297 ± 0.009	11.950 ± 0.128	⋯
43	023340.83+731950.8	6.178 ± 0.007	11.280 ± 0.010	16.950 ± 0.029	24.350 ± 0.031	⋯	⋯
44	023432.66+724057.2	0.243 ± 0.002	⋯	0.636 ± 0.007	⋯	3.180 ± 0.117	⋯
45	023532.06+724922.6	0.079 ± 0.001	0.098 ± 0.002	0.101 ± 0.006	0.138 ± 0.008	2.856 ± 0.133	⋯

Notes.

^aThis flux results from our measurement. ^bHα emission star. ^cThis source is not listed in the SEIP Source List. The identifier is based on the position in the MIPS 70 μm image, and the fluxes were measured as described in Section 2.1. ^dThis source is not listed in the SEIP Source List. The identifier is based on the position in the SEIP Super Mosaic images of the region.

A machine-readable version of the table is available.

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Table 2. SEIP SSTSL2 Fluxes and Uncertainties of Flat SED Sources in L1340

No.	SSTSL2	F_3.6	F_4.5	F_5.8	F_8.0	F₂₄	F₇₀^a^, ^b
		(mJy)	(mJy)	(mJy)	(mJy)	(mJy)	(mJy)
1	022754.00+723535.5	1.744 ± 0.004	1.766 ± 0.020	2.957 ± 0.012	0.245 ± 0.018	⋯	⋯
2	022759.92+723556.4^b	0.523 ± 0.026	0.859 ± 0.060	0.980 ± 0.032	⋯	⋯
3	022811.32+723631.5	4.896 ± 0.086	6.002 ± 0.011	6.895 ± 0.011	7.715 ± 0.014	⋯	⋯
4	022816.62+723732.6	219.545 ± 28.270	268.500 ± 0.135	361.400 ± 0.124	374.611 ± 11.495^a	⋯	⋯
5	022817.85+723800.9	92.280 ± 0.027	108.000 ± 0.056	140.700 ± 0.078	219.498 ± 6.839^a	857.300 ± 0.612	⋯
6	022818.51+723734.6	⋯	9.617 ± 0.021	8.287 ± 0.019	9.695 ± 0.015	⋯	⋯
7	022838.02+723740.6	2.805 ± 0.005	2.963 ± 0.006	3.217 ± 0.012	5.370 ± 0.012	12.010 ± 0.516	⋯
8	022850.36+723851.2	0.822 ± 0.003	0.883 ± 0.004	0.897 ± 0.008	1.218 ± 0.009	4.005 ± 0.180	⋯
9	022851.83+723810.2	2.934 ± 0.005	3.027 ± 0.007	2.980 ± 0.012	3.900 ± 0.012	16.730 ± 0.215	⋯
10	022858.15+723801.4	0.461 ± 0.002	0.607 ± 0.003	0.627 ± 0.007	0.551 ± 0.009	4.872 ± 0.185	⋯
11	022907.88+724347.2	3.938 ± 0.006	5.972 ± 0.010	8.489 ± 0.020	11.680 ± 0.017	30.940 ± 0.142	66.994 ± 5.117
12	022917.57+723904.7	0.735 ± 0.003	0.803 ± 0.005	0.818 ± 0.008	0.853 ± 0.010	⋯	⋯
13	022919.60+730223.5	15.980 ± 0.014	21.360 ± 0.018	26.930 ± 0.036	46.410 ± 0.029	131.700 ± 0.180	181.009 ± 20.0
14	022920.70+730119.0	0.137 ± 0.002	0.171 ± 0.002	0.156 ± 0.005	0.169 ± 0.007	1.491 ± 0.128	⋯
15	022950.37+724441.4	0.069 ± 0.001	0.092 ± 0.002	0.163 ± 0.005	0.341 ± 0.009	0.877 ± 0.120	⋯
16	023020.61+730233.7	30.700 ± 0.023	35.390 ± 0.029	47.510 ± 0.048	61.830 ± 0.034	174.500 ± 0.212	162.696 ± 11.950
17	022920.70+730119.0	0.137 ± 0.002	0.171 ± 0.002	0.156 ± 0.005	0.169 ± 0.007	1.491 ± 0.128
18	023033.71+730125.1	0.957 ± 0.004	1.813 ± 0.005	2.940 ± 0.013	4.755 ± 0.012	11.630 ± 0.134	⋯
19	023049.81+731049.2	0.059 ± 0.002	0.084 ± 0.002	0.128 ± 0.006	0.255 ± 0.007	0.581 ± 0.100	⋯
20	023053.25+730528.5	0.087 ± 0.001	0.109 ± 0.002	0.091 ± 0.005	0.366 ± 0.009	0.871 ± 0.123	⋯
21	023114.12+723933.3	0.480 ± 0.002	0.462 ± 0.004	0.482 ± 0.007	0.568 ± 0.019	2.432 ± 0.125	⋯
22	023127.45+723912.8	0.488 ± 0.002	⋯	0.592 ± 0.007	⋯	2.234 ± 0.132	⋯
23	023127.52+725621.5	0.133 ± 0.001	0.157 ± 0.002	0.150 ± 0.005	0.447 ± 0.009	1.513 ± 0.123	⋯
24	023134.62+725642.0	16.900 ± 0.012	18.840 ± 0.013	19.710 ± 0.031	28.240 ± 0.032	82.320 ± 0.177	180.167 ± 12.921
25	023247.15+723858.8	2.079 ± 0.004	⋯	2.887 ± 0.005	⋯	17.390 ± 0.126	⋯
26	023254.71+724257.9	0.077 ± 0.001	0.132 ± 0.002	0.211 ± 0.005	0.378 ± 0.009	1.131 ± 0.104	⋯
27	023301.52+724326.7	43.430 ± 0.018	63.980 ± 0.025	91.940 ± 0.064	⋯	<0.325	⋯

Notes.

^aThis flux results from our measurements. ^bThis source is not listed in the SEIP Source List. The identifier is based on the position in the SEIP Super Mosaic images, and the fluxes were measured as described in Section 2.1.

A machine-readable version of the table is available.

Download table as: Data Typeset image

Table 3. SEIP SSTSL2 Fluxes and Uncertainties of of Class II Sources

SSTSL2	F_3.6	F_4.5	F_5.8	F_8.0	F₂₄	F₇₀
	(mJy)	(mJy)	(mJy)	(mJy)	(mJy)	(mJy)
022638.02+730457.5^a	3.517 ± 0.147	3.965 ± 0.009	4.335 ± 0.015	5.878 ± 0.015	7.710 ± 0.116	36.198 ± 3.178
022654.73+724040.8	1.552 ± 0.004	1.012 ± 0.004	0.527 ± 0.007	0.461 ± 0.010	4.301 ± 0.179	⋯
022659.03+725716.0	1.477 ± 0.005	1.156 ± 0.003	0.921 ± 0.006	0.739 ± 0.009	5.040 ± 0.115	⋯
022659.08+724016.6^a	0.966 ± 0.003	0.815 ± 0.004	0.667 ± 0.007	0.893 ± 0.009	1.221 ± 0.200	⋯
022659.35+725714.2	1.581 ± 0.005	1.204 ± 0.003	0.981 ± 0.006	1.098 ± 0.009	9.337 ± 0.117	⋯
022700.34+724743.8^a	2.571 ± 0.005	1.920 ± 0.006	1.573 ± 0.009	2.136 ± 0.010	8.947 ± 0.126	⋯
022702.11+724329.0^a	2.061 ± 0.004	1.617 ± 0.006	1.043 ± 0.008	0.968 ± 0.011	2.460 ± 0.123	⋯
022703.17+723952.9^a	1.172 ± 0.003	1.177 ± 0.005	0.794 ± 0.007	1.192 ± 0.009	2.206 ± 0.179	⋯
022705.53+724116.7	169.100 ± 5.464	131.753 ± 5.460^b	125.8 ± 4.288	147.395 ± 4.713^b	197.200 ± 0.303	⋯
022706.29+724011.1^a	1.918 ± 0.070^b	1.344 ± 0.044^b	0.878 ± 0.008	0.912 ± 0.009	2.466 ± 0.181	⋯

Notes.

^aHα emission star, described in detail in Paper III. ^bOur measurement.

Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.

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The SEDs of Class II sources can be divided into further subclasses by comparing the dereddened SED slopes with the median band of the Taurus pre-main-sequence sample (D'Alessio et al. 1999; Furlan et al. 2006). The SED subclasses are indicative of the dust distribution in the circumstellar disks (Evans et al. 2009) of the classical T Tauri stars (CTTSs) and may shed light on the processes governing disk evolution. We classified the infrared excesses of our candidate pre-main-sequence stars into three groups: (1) the SED of primordial disks (II P subclass) does not drop below the Taurus median band; (2) the SED of the weak or anemic disks (II A subclass) is below the Taurus band over the whole observed wavelength region, and (3) pre-transitional and transitional disks (II T) have SEDs below the Taurus median band at intermediate wavelengths and start rising above 20 μm. For the latter group the spectral index α(8–24) > 0.

4.1.3. Submillimeter, Far-infrared, and Optical Counterparts

Six Spitzer sources are associated with submillimeter sources listed in the JCMT SCUBA Fundamental Catalog (Di Francesco et al. 2008). Far-infrared counterparts of 17 candidate Class 0/I and 3 Flat SED YSOs were identified in the Herschel PACS images. Table 4 lists the SSTSL2 associations and 100 and 160 μm fluxes of these Herschel point sources.

Table 4. Herschel PACS Point Sources Associated with Candidate Spitzer YSOs in L1340 C

No.	SSTSL2	Fitted R.A.	Fitted Decl.	F₁₀₀	dF₁₀₀	F₁₆₀	dF₁₆₀
		(degree)	(degree)	(mJy)	(mJy)	(mJy)	(mJy)
1	022907.88+724347.2	37.28481	72.73014	349.372	⋯	1073.854	⋯
2	022943.64+724358.6	37.43316	72.73337	9899.194	⋯	11999.27	⋯
3	023114.12+723933.3	37.82169	72.66068	34.923	353.948	⋯	⋯
4	023127.45+723912.8	37.87831	72.65379	13.773	101.163	0474.558	38.295
5	023127.34+724013.0	37.86170	72.67144	918.261	124.522	1652.396	155.898
6	023146.58+723729.4	37.93610	72.62243	16.760	57.825	0342.640	66.379
7	023203.42+724131.7	38.01794	72.68809	0.424	182.745	0101.090	62.318
8	023207.96+723759.3	38.03459	72.63372	258.719	205.061	0500.088	85.020
9	023225.98+724020.1	38.11119	72.67221	879.202	47.523	1712.686	87.426
10	023226.35+723919.4	38.10945	72.65580	488.341	196.238	2403.526	376.658
11	023227.64+723841.4	38.11722	72.64574	1118.237	187.990	2461.969	379.767
12	023232.00+723827.5	38.13490	72.64143	639.157	122.241	2462.245	379.627
13	023237.90+723940.7	38.15584	72.66280	22.780	114.644	264.833	156.138
14	023247.15+723858.8	38.19769	72.65025	37.372	194.085	175.280	226.861
15	023248.83+724635.4	38.20506	72.77680	75.233	51.971	⋯	⋯
16	023254.71+724257.9	38.22334	72.71396	7.888	142.752	⋯	⋯
17	023256.14+724605.3	38.23558	72.76854	1798.065	105.467	2059.933	84.941
18	023302.41+724331.2	38.26159	72.72580	2621.677	155.127	2801.787	100.030
19	023331.04+724800.8	38.38035	72.80073	119.108	168.020	470.005	69.517
20	023432.66+724057.2	38.63831	72.68040	23.361	173.174	⋯	⋯

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Nine of the Spitzer-selected candidate YSOs coincide in position with far-infrared sources detected by the Akari/FIS instrument (Kawada et al. 2007). Four of them are included in the Akari/FIS YSO catalog (Tóth et al. 2014). A fifth catalog entry, Akari 0232291+723855, has an associated mid-infrared point source, AllWISE 023227.63+723841.4, within the half-maximum radius of the PSF of the FIS (Arimatsu et al. 2014). Its fluxes, however, probably originate from more than one source. Similarly, the far-infrared fluxes of Akari FIS 0230333+725951, a bright candidate YSO detected in each FIS band and associated with IRAS 02259+7246, are composed of several sources. An extended emission can be seen around this position in the Spitzer 70 μm image. We found SDSS counterparts of all but seven Class II infrared sources. A few Flat and Class I sources also have SDSS counterparts. Most of these counterparts are classified as galaxies. The nonstellar appearance, however, may indicate their scattered light origin.

SDSS, 2MASS, AllWISE, Akari, and other identifiers of Class I and flat sources are listed in Tables 5 and 6, respectively. For the Class II sample, excluding the 65 members common with the Hα emission stars studied in Paper III, we give the UBVR_CI_CJHK_s magnitudes in Table A1 of the Appendix.

Table 5. Spitzer Sources of Class 0/I SED: Associated Objects

SSTSL2	SDSS DR9 J	2MASS	AllWISE J	IRAS	Akari FIS	JCMTSF J	Other
022756.91+730354.4	⋯	02275695+7303542	022756.94+730354.6	⋯	0227565+730402	022756.6+730404	⋯
022800.65+730415.2	022800.91+730415.4g	02280074+7304154	022800.60+730415.4	⋯	⋯	⋯	⋯
022808.60+725904.5	⋯	⋯	022808.59+725904.0	⋯	0228071+725858	022808.4+725902	⋯
022818.51+723506.2	⋯	02281842+7235061	022818.46+723506.3	⋯	⋯	⋯	⋯
022820.81+723500.5	⋯	⋯	022820.76+723500.6	⋯	0228201+723504	⋯
022825.07+730945.6	⋯	⋯	022825.06+730945.7	⋯	⋯	⋯	⋯
022842.57+723544.3	022842.55+723544.5g	02284255+7235444	022842.54+723544.5	⋯	⋯	⋯	⋯
022844.40+723533.5	022844.40+723532.9g	02284443+7235332	022844.39+723533.6	⋯	⋯	⋯	⋯
022844.71+730308.5	⋯	⋯	022844.66+730308.6	⋯	⋯	⋯	⋯
022849.44+723731.6	⋯	⋯	022849.40+723732.5	⋯	⋯	⋯	⋯
022855.69+731333.1	⋯	⋯	022855.89+731333.1	02240+7259	⋯	⋯	⋯
022856.61+730903.2	⋯	⋯	022856.62+730903.1	⋯	⋯	⋯	⋯
022906.09+730210.5	⋯	⋯	⋯	⋯	⋯	⋯	⋯
022914.62+730102.8	⋯	⋯	022914.67+725405.5	⋯	⋯	⋯	⋯
022918.25+724754.0	⋯	⋯	⋯	⋯	⋯	⋯	⋯
022931.98+725912.4	⋯	02293228+7259130	022932.05+725913.0	02248+7245	0229320+725911	022933.2+725914
022932.31+725503.2	022932.32+725503.3*	⋯	022932.30+725503.2	⋯	⋯	⋯	⋯
022943.01+724359.6	022943.09+724359.7	⋯	022943.58+724358.6	02249+7230	⋯	⋯	HH 489S
022943.64+724358.6	022949.66+725325.8	⋯	022943.58+724358.6	02249+7230	⋯	⋯	HH 489S
022949.62+725326.1	⋯	⋯	022949.65+725326.3	⋯	⋯	⋯	⋯
022955.10+730309.1	⋯	02295507+7303094	022955.11+730309.4	⋯	⋯	⋯	⋯
022956.90+730217.0	⋯	⋯	022957.34+730211.1	⋯	⋯	022956.9+730217
023022.78+730459.0	⋯	⋯	023022.79+730459.0	⋯	⋯	022956.9+730217
023030.42+725706.7	⋯	⋯	023030.34+725707.0	⋯	⋯	⋯	⋯
023032.44+725918.0	023032.47+725917.7	02303247+7259177	023032.46+725917.8	02259+7246	⋯	⋯	RNO 8
023035.51+730828.2	⋯	⋯	023035.52+730828.5	⋯	⋯	⋯	⋯
023042.36+730305.1	⋯	02304238+7303051	023042.36+730305.2	⋯	⋯	⋯	⋯
023127.34+724012.9	⋯	02312734+7240130	023127.20+724015.5	02267+7226	0231270+724015	⋯	⋯
023134.23+725829.1	⋯	⋯	023134.25+725828.8	⋯	⋯	⋯	⋯
023142.50+725740.4	⋯	⋯	023142.44+725740.6	⋯	⋯	⋯	⋯
023146.58+723729.4	⋯	⋯	023146.53+723729.9	⋯	⋯	⋯	⋯
023203.42+724131.7	⋯	⋯	023203.38+724131.7	⋯	⋯	⋯	⋯
023207.96+723759.3	⋯	⋯	023207.88+723759.6	⋯	⋯	⋯	⋯
023225.98+724020.1	⋯	⋯	023225.96+724020.3	⋯	⋯	⋯	⋯
023226.35+723919.4	023226.57+723919.6g	02322653+7239198	023226.37+723919.5	⋯	⋯	⋯	⋯
023227.64+723841.4	⋯	⋯	023227.63+723841.4	⋯	⋯	⋯	⋯
023232.00+723827.5	023231.70+723826.7	02323198+7238280	023231.92+723828.1	⋯	⋯	⋯	⋯
023237.90+723940.7	⋯	⋯	023237.90+723940.7	⋯	⋯	⋯	⋯
023248.83+724635.4	023248.85+724635.0g	02324885+7246369	023248.77+724635.6	⋯	⋯	⋯	⋯
023256.14+724605.3	⋯	02325605+7246055	023256.14+724605.3	⋯	0232567+724611	⋯	⋯
023302.41+724331.2	⋯	02330247+7243315	023302.41+724331.7	02283+7230	⋯	⋯	[KOS94] HA11B
023330.92+724800.3	⋯	⋯	023331.06+724800.7	⋯	⋯	⋯	⋯
023340.83+731950.8	⋯	02334083+7319510	023340.81+731950.8	⋯	⋯	⋯	⋯
023432.66+724057.2	⋯	⋯	023432.75+724057.2	⋯	⋯	⋯	⋯
023532.06+724922.6	⋯	⋯	023532.07+724922.8	⋯	⋯	⋯	⋯

Download table as: ASCII Typeset image

Table 6. Spitzer Sources of Flat SED: Associated Objects

SSTSL2	SDSS DR9 J	2MASS	AllWISE J	IRAS	Akari FIS	JCMTSF J	Other
022754.00+723535.5	022753.97+723535.5*	02275399+7235354	022753.96+723535.7	⋯	⋯	⋯	⋯
022759.92+723556.4	022759.78+723555.6*	02275976+7235561	022759.92+723556.4	⋯	⋯	⋯	HH 488S
022811.32+723631.5	022811.27+723631.6g	02281130+7236316	022811.29+723631.6	⋯	⋯	⋯	⋯
022816.62+723732.6	022816.63+723733.0*	02281661+7237328	022816.62+723732.8	02236+7224	⋯	⋯	[KOS94] HA 1, RNO 7-5
022817.85+723800.9	022817.85+723801.0*	02281782+7238009	⋯	⋯	⋯	⋯	[KOS94] HA 2, RNO 7-7
022818.51+723734.6	⋯	02281847+7237347	⋯	⋯	⋯	⋯	⋯
022838.02+723740.6	022838.03+723740.8g	02283804+7237407	022838.01+723740.8	⋯	⋯	⋯	⋯
022850.36+723851.2	022850.35+723851.0*	02285031+7238506	022850.29+723851.4	⋯	⋯	⋯	⋯
022851.83+723810.2	022851.83+723810.1g	02285183+7238102	022851.81+723810.2	⋯	⋯	⋯	⋯
022858.15+723801.4	⋯	⋯	022858.06+723802.4	⋯	⋯	⋯	⋯
022907.88+724347.2	⋯	02290783+7243475	022907.89+724347.5	⋯	⋯	⋯	⋯
022917.57+723904.7	⋯	02291777+7239045	022917.49+723904.6	⋯	⋯	⋯	⋯
022919.60+730223.5	022919.61+730223.6*	02291961+7302237	022919.60+730223.7	F02246+7248	⋯	022921.2+730221	⋯
022920.70+730119.0	022920.65+730119.6g	⋯	022920.66+730119.5	⋯	⋯	⋯	⋯
023020.61+730233.7	023020.60+730233.8*	02302061+7302338	023020.60+730233.9	⋯	⋯	⋯	⋯
023033.71+730125.1	023033.68+730125.0*	⋯	023033.72+730125.1	⋯	⋯	⋯	⋯
023049.81+731049.2	⋯	⋯	023049.72+731049.6	⋯	⋯	⋯	⋯
023053.25+730528.5	⋯	⋯	023053.55+730528.1	⋯	⋯	⋯	⋯
023114.12+723933.3	023114.07+723933.4*	⋯	023114.11+723933.3	⋯	⋯	⋯	⋯
023127.45+723912.8	⋯	⋯	023127.40+723913.1	⋯	⋯	⋯	⋯
023127.52+725621.5	⋯	⋯	⋯	⋯	⋯	⋯	⋯
023134.62+725642.0	023134.55+725640.8g	02313460+7256421	023134.60+725642.2	⋯	⋯	⋯	⋯
023247.15+723858.8	⋯	02324717+7238590	023246.98+723859.0	⋯	⋯	⋯	⋯
023254.71+724257.9	⋯	⋯	⋯	⋯	⋯	⋯	⋯
023301.52+724326.7	023301.53+724326.8*	02330153+7243269	023301.49+724327.0	02283+7230	⋯	⋯	V1180 Cas

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The SEDs of the candidate YSOs, constructed from all available data, are displayed in Figures 9–11 for the Class I, Flat, and Class II sources, respectively. Since the SEDs of the Hα emission stars, together with those of the best-fitting photospheres, have been presented in Figure 9 of Paper III, Figure 11 presents the results for the Class II subsample not detected as Hα emission stars during our slitless spectroscopic Hα survey. The dereddened SEDs, as well as the best-fitting photosphere (Pecaut & Mamajek 2013), are also plotted, and the derived spectral type and extinction are indicated in each plot.

Figure 9. — Download figure:
Standard image High-resolution image

Figure 10. — Download figure:
Standard image High-resolution image

Figure 11. — Download figure:
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4.1.4. Bolometric Temperatures and Luminosities

Bolometric temperatures and luminosities, as defined in Myers & Ladd (1993), were derived from the dereddened SEDs for the Class I and Flat SED objects, detected at least in one band beyond 24 μm, and for the Class II sources, detected over the 0.36–24 μm region. Akari FIS, Herschel PACS, and JCMTSF submillimeter data were included in the integration when available. Contribution of the spectral regions beyond the longest wavelength was estimated using the method described by Chavarría-K (1981). The L_bol versus T_bol diagram of the candidate YSOs is plotted in Figure 12. The YSO classes, defined by the spectral slopes, correspond to the T_bol intervals indicated in Figure 12 (Chen et al. 1995). It can be seen that both α(2–24) and T_bol are consistent with the Class 0/I identification. Flat SED sources overlap in T_bol with both Class I and Class II, whereas a significant part of the Class II sample has T_bol above the theoretical boundary of 2800 K. It is in accordance with the recent finding of Dunham et al. (2015) that the extinction-corrected T_bol of a Class II source depends on the T_eff of the central star, rather than on the disk properties. Figure 13 shows the histogram of bolometric luminosities of the candidate YSOs. The mean L_bol of the 28 Class I sources, detected at λ > 24 μm, is $\langle {L}_{\mathrm{bol},\mathrm{ClassI}}\rangle =3.4\;{L}_{\odot }$ , and that for the Class II sample is $\langle {L}_{\mathrm{bol},\mathrm{ClassII}}\rangle =1.2\;{L}_{\odot }$ .

**Figure 12.** Extinction-corrected bolometric luminosities plotted against extinction-corrected bolometric temperatures. Red plus signs indicate Class 0/I sources, green plus signs are for Flat, and blue plus signs are for Class II SED slopes. Vertical dashed lines indicate the boundaries between the classes, and the dot-dashed line indicates the position of the zero-age main sequence (Siess et al. 2000).
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**Figure 13.** Histogram of bolometric luminosities of Class 0/I/Flat protostars and Class II pre-main-sequence stars.
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Tables 7 and 8 present the derived extinctions, extinction-corrected SED slopes, bolometric temperatures, and luminosities of Class 0/I and Flat SED sources, respectively. Table 9, in addition to the above quantities, lists the derived spectral types and luminosities for central stars of the Class II sources, as well as the SED subclasses.

Table 7. Extinctions, Extinction-corrected Spectral Indices, Bolometric Temperatures, and Luminosities of Class 0/I Sources of L1340

SSTSL2	A_V	$\alpha (K-24)$	α(3.6–24)	α(3.6–8.0)	α(24–70)	T_bol	L_bol
	(mag)					(K)	(L_☉)
022756.91+730354.4	4.6	0.79	0.81	1.16	1.20	108	4.40
022800.65+730415.2	4.7	0.16	0.44	0.17	−0.71	664	2.72
022808.60+725904.5	2.2	⋯	−1.06	−1.14	4.28	55	3.54
022818.51+723506.2	3.6	1.18^a	1.38^b	1.52	⋯	⋯	⋯
022820.81+723500.5	3.6	⋯	2.34^b	2.98	⋯	42	22.81
022825.07+730945.6	2.8	⋯	1.59	1.93	−0.41	149	0.15
022842.57+723544.3	1.7	0.71^a	0.63^b	0.14	⋯	⋯	⋯
022844.40+723533.5	1.7	0.48^a	0.64^b	⋯	⋯	⋯
022844.71+730308.5	1.8	⋯	1.66	−0.54	⋯	⋯	⋯
022849.44+723731.6	3.6	⋯	1.21	0.77	⋯	⋯	⋯
022855.69+731333.1	1.3	⋯	0.60	1.10	⋯	340	0.01
022856.61+730903.2	1.4	⋯	0.75	0.25	⋯	⋯	⋯
022906.09+730210.5	2.7	⋯	0.74	0.12	⋯	⋯
022914.62+730102.8	3.1	⋯	0.52	⋯	⋯	⋯	⋯
022918.25+724754.0	1.1	⋯	0.97	2.51	1.66	82	0.11
022931.98+725912.4	1.5	1.43	1.82	3.73	1.02	71	7.93
022932.31+725503.2	1.7	⋯	0.64	0.53	⋯	⋯	⋯
022943.01+724359.6	1.4	⋯	⋯	⋯	⋯	⋯	⋯
022943.64+724358.6	2.5	1.14	1.61	1.68	0.72	132	10.77
022949.62+725326.1	2.5	⋯	1.74	2.29	−0.39	410	0.35
022955.10+730309.1	2.8	0.77	0.74	0.22	−1.14	323	0.41
022956.90+730217.0	4.2	⋯	⋯	⋯	⋯	31	5.17
023022.78+730459.0	3.3	⋯	0.50	0.55	⋯	215	0.23
023030.42+725706.7	3.9	0.66	0.65	0.15	⋯	⋯	⋯
023032.44+725918.0	3.3	0.79	0.72	0.65	−1.06	743	14.69
023035.51+730828.2	1.2	⋯	0.32	1.07	⋯	⋯	⋯
023042.36+730305.1	2.4	1.00	0.62	0.23	0.31	259	1.50
023127.34+724012.9	2.2	⋯	0.96	0.64	0.71	102	2.74
023134.23+725829.1	2.1	⋯	0.31	−0.65	⋯	⋯
023142.50+725740.4	3.3	⋯	0.42	1.48	⋯	⋯	⋯
023146.58+723729.4	2.5	⋯	0.71^b	⋯	⋯	57	0.23
023203.42+724131.7	3.9	⋯	1.67	1.16	⋯	180	0.07
023207.96+723759.3	2.3	⋯	0.70	1.10	0.64	112	0.62
023225.98+724020.1	5.2	⋯	0.61	0.75	0.91	109	2.17
023226.35+723919.4	2.4	0.16	0.63	0.71	0.48	138	0.96
023227.64+723841.4	3.8	⋯	0.58	⋯	1.74	80	0.77
023232.00+723827.5	6.0	0.36	0.14	0.62	0.62	508	2.36
023237.90+723940.7	4.8	⋯	⋯	1.60	⋯	55	0.28
023248.83+724635.4	2.2	⋯	0.35	1.44	⋯	108	0.16
023256.14+724605.3	1.6	0.84	0.95	−0.38	1.48	69	2.59
023302.41+724331.2	1.7	1.58	1.41	1.50	0.38	119	6.46
023330.92+724800.3	2.8	⋯	1.21	⋯	⋯	59	0.44
023340.83+731950.8	3.3	1.26^a	1.15^b	0.67	⋯	⋯	⋯
023432.66+724057.2	2.2	⋯	0.36	⋯	⋯	⋯	⋯
023532.06+724922.6	1.5	⋯	0.90	1.02	1.78	⋯	⋯

Notes.

^a $\alpha (K-22)$ $\alpha (K-22)$ , since this source is outside of the MIPS images. ^bα(3.4–22), since this source is outside of the MIPS images.

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Table 8. Extinctions, Extinction-corrected Spectral Indices, Bolometric Temperatures, and Luminosities of Flat SED Sources

SSTSL2	A_V	$\alpha (K-24)$	α(3.6–24)	α(3.6–8.0)	T_bol	L_bol
	(mag)				(K)	(L_☉)
022754.00+723535.5	3.3	−0.03^a	0.19^b	⋯	2393	0.15
022759.92+723556.4	0.9	−0.17^a	−0.19^b	⋯	2674	0.06
022811.32+723631.5	2.6	−0.14^a	0.03^b	−0.43	2726	0.43
022816.62+723732.6	3.8	0.25^a	0.13^b	0.02	3472	28.48
022817.85+723800.9	2.0	0.00	0.02	−0.18	1377	10.16
022818.51+723734.6	3.6	⋯	⋯	−0.14	⋯	⋯
022838.02+723740.6	3.5	−0.32	−0.24	−0.32	2706	0.30
022850.36+723851.2	3.0	−0.13	−0.17	−0.51	⋯	⋯
022851.83+723810.2	4.0	0.08	−0.11	−0.62	1647	0.22
022858.15+723801.4	3.2	⋯	0.24	−0.78	⋯	⋯
022907.88+724347.2	2.9	−0.01	0.05	0.27	1006	0.51
022917.57+723904.7	1.5	−0.20^a	0.02^b	−0.81	1499	0.03
022919.60+730223.5	4.7	0.06	0.11	0.34	1378	1.87
022920.70+730119.0	3.1	⋯	0.26	−0.73	⋯	⋯
022950.37+724441.4	3.8	⋯	0.28	−0.23	⋯	⋯
023020.61+730233.7	2.2	−0.04	−0.11	−0.19	1049	2.13
023033.71+730125.1	2.1	⋯	0.31	0.93	512	0.07
023049.81+731049.2	4.2	⋯	0.21	0.83	⋯	⋯
023053.25+730528.5	2.9	⋯	0.22	0.80	⋯	⋯
023114.12+723933.3	2.2	⋯	−0.15	−0.79	821	0.10
023127.45+723912.8	2.9	⋯	−0.20	⋯	92	0.30
023127.52+725621.5	3.2	⋯	0.28	0.52	⋯	⋯
023134.62+725642.0	3.6	−0.24	−0.19	−0.48	1096	1.71
023247.15+723858.8	3.6	−0.04	−0.02	⋯	1104	0.20
023254.71+724257.9	1.8	⋯	0.38	−0.05	⋯	⋯
023301.52+724326.7	2.7	⋯	0.13^b	⋯	572	2.54

Notes.

^a $\alpha (K-22)$ $\alpha (K-22)$ , since this source is outside of the MIPS images. ^bα(3.6–22), since this source is outside of the MIPS images.

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Table 9. Properties of Class II Objects Derived from the SEDs

SSTSL2	Sp	A_V	T_eff	L_star	T_bol	L_bol	$\alpha (K-24)$	α(3.6–8.0)	α(8–24)	SED Subtype
		(mag)	(K)	(L_☉)	(K)	(L_☉)
022638.02+730457.5^a	K4	0.7	4330	0.33	2556	0.56	−0.76	−0.38	−0.77	II P
022654.73+724040.8	M1	1.4	3630	0.30	3184	0.34	−0.96	−2.58	1.04	II T
022659.03+725716.0	M0	1.6	3770	0.34	3198	0.41	−0.96	−1.94	0.75	II T
022659.08+724016.6^a	M1	1.5	3630	0.14	3183	0.16	−1.15	−1.18	−0.73	II A
022659.35+725714.2	M1	1.7	3630	0.33	3008	0.44	−0.71	−1.53	0.95	II T
022700.34+724743.8^a	K3	1.3	4550	0.79	3916	0.83	−0.87	−1.27	0.30	II T
022702.11+724329.0^a	K9	2.2	3770	0.41	3447	0.40	−1.20	−2.06	−0.17	II T
022703.17+723952.9^a	M0	1.5	3770	0.13	3052	0.15	−0.82	−1.05	−0.45	II P
022705.53+724116.7	G5	2.0	5500	31.98	3882	31.14	−1.18	⋯	⋯	II A
022706.29+724011.1^a	M0	1.8	3770	0.26	3232	0.32	−1.15	⋯	−0.10	II A

Notes.

^aHα emission star. ^b $\alpha (K-22)$ $\alpha (K-22)$ , since this source is outside of the MIPS images. ^cα(3.6–5.8). ^dα(3.6–24).

Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.

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4.2. New Candidate Members of RNO 7 in the Omega-Cass Data

The three-color composite of the J (blue), H (green), and K (red) Omega-Cass images is shown in the second panel of Figure 14. For comparison, we show in the first panel an optical three-color view of the same region, composed of the SDSS g (blue), r (green), and i (red) images, whereas the third panel shows the Spitzer 3.6 μm (blue), 4.5 μm (green), and 8 μm (red) composite image. The high angular resolution Omega-Cass images reveal a few new objects, detectable neither in the optical nor in the IRAC images. Furthermore, they show that the brightest member of RNO 7, SSTSL2 J022816.62+723732.6, associated with IRAS 02236+7224, has a faint companion at an angular distance of 1 farcs 12 (Figure 14, fourth panel), corresponding to some 760 au at a distance of 825 pc.

The magnitudes measured in the Omega-Cass images and transformed into the 2MASS system are compared with the 2MASS magnitudes of the same stars in the left panel of Figure 15. The right panel of Figure 15 shows the J − H versus H − K_s two-color diagram of the stars measured in each band. Twenty stars are located to the right of the band of the reddened normal main-sequence and giant stars, indicating K_s-band excess. Table 10 lists the derived magnitudes of these stars. All but two of them have 2MASS counterparts, but none of them have good (A or B) photometric quality in each band. Six of the 14 Hα emission stars, discovered by Magakian et al. (2003), and seven Spitzer-identified candidate YSOs are found in this sample. Eight stars, marked with asterisks in Table 10, are new candidate members of RNO 7. The SEDs of these eight stars, constructed from all available data, are presented in Figure 16.

**Figure 15.** Left: 2MASS magnitudes of 17 stars within the field of view of Omega-Cass, plotted against those measured in the Omega-Cass images. Right: J − H vs. $H-{K}_{{\rm{s}}}$ two-color diagram of the stars in the region of RNO 7, detected in each band in the Omega-Cass images, and listed in Table 10. The solid line indicates the colors of the main-sequence stars, and the dotted line shows those of the giants (Bessell & Brett 1988). Dashed lines border the band of the reddened main-sequence and giant stars, and the dot-dashed line is the locus of T Tauri stars (Meyer et al. 1997). Red filled circles indicate the known Hα emission stars, and open circles show the stars selected as Class II infrared sources in the *Spitzer* data.
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**Figure 15.** Left: 2MASS magnitudes of 17 stars within the field of view of Omega-Cass, plotted against those measured in the Omega-Cass images. Right: J − H vs. $H-{K}_{{\rm{s}}}$ two-color diagram of the stars in the region of RNO 7, detected in each band in the Omega-Cass images, and listed in Table 10. The solid line indicates the colors of the main-sequence stars, and the dotted line shows those of the giants (Bessell & Brett 1988). Dashed lines border the band of the reddened main-sequence and giant stars, and the dot-dashed line is the locus of T Tauri stars (Meyer et al. 1997). Red filled circles indicate the known Hα emission stars, and open circles show the stars selected as Class II infrared sources in the *Spitzer* data.
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**Figure 16.** SEDs of the candidate young stars identified in the Omega-Cass *JHK* data.
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Table 10. NIR-excess Stars Identified in the Omega-Cass Images

N	J ± ΔJ	H ± ΔH	K ± ΔK	2MASS	Other ID/Position
1	15.776 ± 0.020	15.258 ± 0.016	14.736 ± 0.011	02280836+7237183	SSTSL2 J022808.36+723718.1
2	13.034 ± 0.011	11.828 ± 0.030	10.780 ± 0.030	02281182+7236447	RNO 7-3
3^a	15.625 ± 0.017	15.192 ± 0.024	14.562 ± 0.030	⋯	02 28 12.50+72 36 44.0
4^a	14.631 ± 0.020	13.170 ± 0.020	12.264 ± 0.020	02281643+7237517	⋯
5^a	15.531 ± 0.027	14.921 ± 0.015	13.893 ± 0.022	02281673+7238090	⋯
6	11.400 ± 0.025	10.236 ± 0.014	9.100 ± 0.011	02281661+7237328	RNO 7-5
7^a	17.097 ± 0.018	15.827 ± 0.017	14.961 ± 0.023	⋯	02 28 17.35+72 37 54.5
8^a	16.375 ± 0.010	15.050 ± 0.015	14.037 ± 0.030	02281720+7237243	⋯
9	13.969 ± 0.025	12.848 ± 0.014	12.157 ± 0.011	02281748+7237384	RNO 7-6
10	12.381 ± 0.025	10.755 ± 0.014	9.384 ± 0.011	02281782+7238009	RNO 7-7
11	12.497 ± 0.025	11.254 ± 0.014	10.146 ± 0.011	02281818+7238069	RNO 7-10
12^a	17.012 ± 0.015	15.796 ± 0.016	14.986 ± 0.060	02281805+7237237	SSTSL2 022818.13+723743.7
13^a	15.099 ± 0.026	13.977 ± 0.014	13.244 ± 0.021	02281840+7237479	⋯
14	12.737 ± 0.015	11.854 ± 0.014	11.179 ± 0.011	02281877+7238091	RNO 7-11
15	16.628 ± 0.012	14.529 ± 0.014	12.934 ± 0.001	02281847+7237347	SSTSL2 J022818.51+723734.6
16	17.589 ± 0.017	15.900 ± 0.017	14.659 ± 0.040	02282239+7238085	SSTSL2 J022822.40+723808.4
17^a	16.818 ± 0.012	16.179 ± 0.028	15.736 ± 0.040	⋯	SSTSL2 J022822.92+723830.5
18	17.384 ± 0.014	15.467 ± 0.010	14.300 ± 0.012	02282402+7238065	SSTSL2 022824.04+723806.4
19	15.611 ± 0.016	14.736 ± 0.004	14.177 ± 0.012	02282623+7237454	SSTSL2 022826.25+723745.4
20	17.192 ± 0.014	16.383 ± 0.008	15.899 ± 0.016	02283047+7237245	SSTSL2 022830.47+723724.2

Note.

^aNew candidate YSO.

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4.3. AllWISE Sources

The 1 square degree area centered on R.A.(J2000) = 37 fdg 625, decl.(J2000) = +72 fdg 933 contained 954 sources, having signal-to-noise ratio greater than 5.0 in each band and not affected by the uppercase contamination flag. We identified seven new Class II source candidates in the WISE database outside the area covered by the Spitzer images, but within the lowest significant ¹³CO contours of the molecular cloud. Each of them is located near the southern boundary of the cloud. Furthermore, two WISE sources without coinciding SSTSL2 entries, J022759.92+723556.4 and J023227.63+723841.4, were found within the field of view of the Spitzer observations. We measured their fluxes in the available bands and added the sources to Tables 2 and 1, respectively. The selected AllWISE sources are listed in Table 11. The SEDs of the seven WISE sources, identified as candidate YSOs outside the field of view of the Spitzer observations, are displayed in Figure 17. Each of them is a Class II source. Their A_V extinctions, spectral types, and luminosities derived from the photometric data are listed in Table 12.

**Figure 17.** SEDs of the candidate young stars identified in the AllWISE data, located outside of the field of view of the *Spitzer* observations.
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Table 11. AllWISE Point Sources Selected as Candidate YSOs

AllWISE	[3.4]	[4.6]	[12.0]	[22.0]
	(mag)	(mag)	(mag)	(mag)
022759.92+723556.4^a^,^b	14.060 ± 0.026	12.460 ± 0.023	10.328 ± 0.076	8.475 ± 0.322
023037.18+723037.0^a	11.198 ± 0.023	10.652 ± 0.021)	8.699 ± 0.026)	6.673 ± 0.076)
023043.49+722812.2	10.593 ± 0.024	10.179 ± 0.020)	9.014 ± 0.029)	6.280 ± 0.062)
023044.85+722639.8	11.975 ± 0.024	11.503 ± 0.021)	10.095 ± 0.054)	8.145 ± 0.199)
023147.07+722722.0	11.360 ± 0.022	10.944 ± 0.021)	8.830 ± 0.028)	6.953 ± 0.079)
023202.38+722820.3	12.646 ± 0.024	12.103 ± 0.023)	10.272 ± 0.075)	7.656 ± 0.145)
023209.62+722858.8	11.206 ± 0.022	10.896 ± 0.020)	9.179 ± 0.033)	6.312 ± 0.060)
023212.59+723013.7^a	11.086 ± 0.023	10.352 ± 0.021)	8.275 ± 0.022)	6.286 ± 0.050)
023227.63+723841.4^b	14.231 ± 0.027	12.630 ± 0.023	12.249 ± 0.339	6.632 ± 0.064

Notes.

^aHα emission star (Paper III). ^bThis source is located within the field of view of the Spitzer observations, but missing from the SEIP Source List.

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Table 12. Properties of Class II AllWISE Sources, Derived from the SEDs

AllWISE	Sp.	A_V	T_eff	(L_star/ L_☉)	$\alpha (K-22)$	SED Subtype
023037.18+723037.0	K4	3.3	4330	1.377	−1.101	II A
023043.49+722812.2	K4	1.0	4330	2.070	−1.063	II A
023044.85+722639.8	M0	1.8	3770	0.278	−1.112	II A
023147.07+722722.0	K4	1.5	4330	1.064	−0.930	II A
023202.38+722820.3	K6	1.8	4020	0.222	−0.713	II T
023209.62+722858.8	K4	1.0	4330	1.089	−0.797	II T
023212.59+723013.7	K1	3.8	4920	0.864	−0.811	II P

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4.4. Embedded Protostars and Herbig–Haro Objects in L1340

4.4.1. Candidate Class 0 Sources

The extinction-corrected SED slopes revealed the presence of 45 Class 0/I and 27 Flat SED candidate YSOs. Eight sources have T_bol ≲ 70 K, suggesting the Class 0 evolutionary stage (Myers & Ladd 1993). These are as follows.

1.
SSTSL2 J022808.60+725904.5 coincides with an Akari FIS and a JCMTSF submillimeter source (see Table 5). Its SED, assembled from all available data (Figure 9), shows deep silicate absorption around 10 μm, suggesting a Class 0 protostar seen at high inclination (Enoch et al. 2009). This object is associated with a parsec-scale outflow identified in H₂ 2.12 μm observations (J. Walawender et al. 2016, in preparation). The three-color image of its environment, composed of IRAC 8 μm (red), 4.5 μm (green), and 3.6 μm (blue) images and displayed in Figure 18, shows 4.5 μm emission, originating from shocked H₂.
2.
SSTSL2 J022820.81+723500.5 lies outside the MIPS 70 μm image. Its steeply rising SED is revealed by the Akari FIS data. With L_bol ≈ 23 L_☉, it is the most luminous protostar of L1340. This source, together with another nearby Class I source, 022818.51+723506.2, is located along the chain of Herbig–Haro objects HH 488, whose several knots were detected in optical Hα and S ii images by Kumar et al. (2003) and Magakian et al. (2003). Kumar et al. (2003) suggested that the driving source was the brighter component of a binary star located at 2^h28^m00^s, 72°35'58'' (HH 488 S, Source 2 in Table 2). The optical counterpart of HH 488 S is classified as a galaxy in the SDSS DR9 and as an HH object by Magakian et al. (2003). Our photometry suggests a Flat SED, although it results from the composite fluxes of the central objects. The positions of the two protostars with respect to the HH knots suggest that either of them is the probable driving source. The IRAC images reveal new knots of HH 488. In the upper panel of Figure 19 we marked the known and new knots of HH 488 and the candidate driving sources. The lower panel shows a three-color composite image of HH 488, whose angular extension of 56 corresponds to a total length of some 1.3 pc at a distance of 825 pc.
3.
SSTSL J022931.98+725912.4 is associated with IRAS and Akari far-infrared and a JCMTSF submillimeter source (Table 7). It is associated with a small fan-shaped reflection nebulosity, bright at 3.6 μm on the eastern side, and a jet-like feature, bright at 4.5 μm on the western side (Figure 20).
4.
The fourth candidate Class 0 protostar is the 70 μm source No. 22 in Table 1. It is associated with the brightest submillimeter source of the region.
5.
SSTSL 023256.14+724605.3 is an embedded eruptive young star in L1340 C, discussed in Kun et al. (2014). Its T_bol and L_bol were determined including the Herschel 100 and 160 μm fluxes.
6.
SSTSL 023146.58+723729.4, 023237.90+723940.7, and 023330.92+724800.3 are low-luminosity sources, not detected in the 70 μm MIPS image. Their low bolometric temperatures were revealed by including the Herschel 100 and 160 μm data in the SEDs. Their nature is uncertain: they may be either very low luminosity protostars or faint distant galaxies.

**Figure 18.** Three-color image composed from IRAC 8 μm (red), 4.5 μm (green), and 3.6 μm (blue) images of the candidate Class 0 protostar SSTSL2 J022808.60+725904.5. The 4.5 μm knots at both sides of the nebulous source indicate HH objects driven by the Class 0 protostar, and corresponding to the protostellar outflow reported in J. Walawender et al. (2016, in preparation).
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**Figure 19.** Top: HH 488 in the 3.6 μm IRAC band. The HH knots A, B, C, and D and the binary star S1+S2, the driving source candidate identified by Kumar et al. (2003), are indicated by the black characters, and red characters mark the new protostars SSTSL2 022818.51+723506.2 and SSTSL2 022820.81+723500.5 and HH knots E, F, and G, revealed by the *Spitzer* images. Bottom: three-color image of the same region, composed from IRAC 8 μm (red), 5.8 μm (green), and 3.6 μm (blue) images.
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**Figure 20.** Three-color image, composed of the IRAC 3.6 μm (blue), 4.5 μm (green), and 8 μm (red) images of the environment of the candidate Class 0 protostar SSTSL2 J022931.98+725912.4. Notice the color difference between the eastern and western nebulosities.
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4.4.2. Class I Protostars Associated with IRAS Sources

Six IRAS sources, listed in Table 6 of Paper I, are associated with Class I Spitzer sources (see Table 5). IRAS 02249+7230 in L1340 A is the driving source of HH 489 (Magakian et al. 2003). The Spitzer data show it to be a wide binary, consisting of two Class I sources, SSTSL2 J022943.01+724359.6 and SSTSL2 J022943.64+724358.6, separated by 2 farcs 8. Their SEDs are shown in Figure 9, and the environment is displayed in the three-color image in Figure 21. HH 489 A, identified in optical Hα and S ii images by Magakian et al. (2003), and a chain of faint HH knots to the south can clearly be seen. Their projected distribution suggests that both components of the binary and another nearby Class I source, SSTSL2 J022950.37+724441.4, may contribute to their excitation.

**Figure 21.** Three-color image, composed from the IRAC 3.6 μm (blue), 4.5 μm (green), and 8 μm (red) images of the environment of the binary protostar IRAS 02249+7230, the driving source of HH 489. HH 489 A and further HH objects revealed by the 4.5 μm image are marked by the green circles. The faint red object within the red circle is another Class I object, SSTSL2 J022950.37+724441.4. The inset in the lower right corner shows the 30'' environment of the central object, magnified and scaled for better visibility.
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Figure 12 shows that T_bol of the second-brightest Class I object of L1340 falls into the Class II regime near the Class I/Class II boundary. This ambiguous classification belongs to SSTSL2 J023032.44+725918.0, associated with IRAS 02259+7246 and RNO 8. A faint optical star is visible at its position. Our low-resolution spectrum (Paper III) reveals its late G spectral type with the Balmer lines in emission, and the optical color indices point to an unreddened star. The bolometric luminosity, determined from the I_C or J magnitudes, places this star near the ZAMS. All these data suggest the high inclination of the disk of this star. The optical and infrared images confirm this statement. Three-color images, shown in Figure 22, reveal the connections between various components of the circumstellar environment of RNO 8. The gap between the star and the nebulosity in the optical three-color image (first panel of Figure 22) suggests a huge shadow of the circumstellar disk on the dusty envelope, stretching far beyond the disk. The image composed of the optical g (blue), IRAC 3.6 μm (green), and IRAC 8 μm (red) shown in the second panel of Figure 22 reveals streaks of 8 μm emission overlapping with the reflected starlight. The image in the third panel is composed of the 4.5 μm (blue), 8 μm (green), and 24 μm (red) images. The overplotted contours of the 70 μm emission reveal a cloud core associated with RNO 8.

**Figure 22.** Upper left panel: optical three-color image of RNO 8, composed from the SDSS g (blue), r (green), and i (red) images. Upper right panel: three-color image of the same region composed of SDSS g (blue), IRAC 3.6 μm (green), and IRAC 8 μm (red) images. Lower panel: three-color image composed of the IRAC 4.5 μm (blue), 8.0 μm (green), and MIPS 24 μm (red) images. Light gray contours show the distribution of the 70 μm emission.
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In L1340 C a J-shaped chain, consisting of five Class I and four Class II YSOs, can be seen close to the extinction peak (see Figure 29). IRAS 02276+7225 and Akari FIS 0232291+723855 are situated in the same area, but neither of them can be unambiguously associated with mid-infrared sources. Similarly, IRAS 02267+7226 and Akari FIS 0231270+724015 coincide with the Class I source SSTSL2 J023127.34+724012.9 within the position uncertainties, but other nearby sources may contribute to their cataloged fluxes.

SSTSL2 J023302.41+724331.2, coinciding with IRAS 02283+7230, is the Class I companion of the eruptive star V1180 Cas. This protostar drives a jet, detected by Antoniucci et al. (2014) in [S ii] and Hα narrowband images. The IRAC 4.5 μm image also clearly shows the jet (Figure 23), as well as several faint HH objects. The 8 μm image reveals a probable third component of the system, located at 4 farcs 8 toward the north–northwest from V1180 Cas.

**Figure 23.** Same as Figure 20, but for the environment of V1180 Cas. In addition to the jet, emanating northward from the Class I component (Antoniucci et al. 2014), several fainter HH knots can be detected. A third component of the system emerges in the 8 μm image. The inset shows an 18'' × 18'' area of the central objects.
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IRAS 02240+7259, detected at 100 μm only by IRAS and thus not listed in Paper I, coincides with a faint candidate protostar SSTSL2 J022855.69+731333.1, not detected at 70 μm. Taking into account the IRAS 100 μm flux, the SED suggests a Class 0/I source with T_bol ≈ 75 K. The nature of this source, however, is uncertain: it may be a distant galaxy.

4.5. Classical T Tauri Stars

The Spitzer, WISE, and Omega-Cass data resulted in 170 Class II young stars in the region of L1340. These stars represent the CTTS population of L1340. Sixty-five of the 77 Hα emission stars, presented in Paper III, are members of this sample. These stars are marked with asterisks in Tables 3 and 9. Histograms of their K_s magnitudes and derived A_V and T_eff values are shown in Figure 24, together with those of the Hα emission subset (Paper III). It can be seen that Hα emission was detected in brighter and hotter Class II stars. Only five of the Class II stars brighter than K_s = 11.5 were not detected during the Hα survey, and only one Hα emission star has spectral type later than M2. The derived extinctions of the Class II sources peak between 2 mag < A_V < 3 mag.

**Figure 24.** Histogram of the K_s magnitudes (left), visual extinctions (middle), and effective temperatures/spectral types (right), derived from photometric data of the candidate pre-main-sequence stars of L1340.
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After estimating their spectral classes and extinctions, we plotted the positions of all candidate pre-main-sequence stars in the log T_eff–log L plane. The intermediate-mass young main-sequence stars, identified in Paper III, are also plotted. Effective temperatures of the spectral types were adopted from Pecaut & Mamajek (2013). Bolometric luminosities were derived from the extinction-corrected I_C and J magnitudes, separately, using the bolometric corrections and color indices tabulated for pre-main-sequence stars by Pecaut & Mamajek (2013), and adopting the distance of 825 pc. Finally, the results obtained from the I_C and J magnitudes were averaged. Figure 25 shows the Hertzsprung–Russell diagram (HRD). Evolutionary tracks and isochrones for the 0.1 M_☉ ≤ M_star ≤ 5.0 M_☉ interval are from Siess et al. (2000), and the track for 0.07 M_☉ from Baraffe et al. (2015) is also plotted. Most of the candidate YSOs are located between the 10⁶ and 10⁷ yr isochrones, confirming their pre-main-sequence star nature at 825 pc from us. Exceptions are a few Class II objects close to or below the ZAMS. The SEDs of these stars suggest that their disks have high inclinations, and thus most of the optical fluxes arise from scattered light (see Paper III for further details). The HRD suggests a mass range between 0.07 M_☉ (M5 type) and 2.5 M_☉ (G- to early K-type stars, evolving toward higher T_eff).

**Figure 25.** HRD of the candidate young population of L1340. Blue star symbols indicate the stars earlier than F5 (Paper III); red filled circles show Class II sources with Hα emission detected (Paper III). Open diamonds indicate Class II sources not detected during our Hα survey. Black dotted lines indicate evolutionary tracks, and thin solid lines mark the 1 × 10⁶, 3 × 10⁶, 5 × 10⁶, and 10⁷ yr isochrones from Siess et al. (2000). The track for 0.07 M_☉ (purple dotted line) is from Baraffe et al. (2015). The bolometric luminosities of the selected sources were calculated for a distance of 825 pc.
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We examined whether the average properties of stars surrounded by primordial (SED subtype II P in Table 9), weak (II A), and transitional (II T) disks can be distinguished or not. Table 13 shows the mean K_s magnitudes and derived mean A_V, T_eff, L_star, T_bol, and L_bol values of the three groups. The table shows that most of the candidate CTTSs of L1340 have weak (anemic) disks. We find that the central stars of primordial disks are brighter in each photometric band and have higher average T_eff than the others, in accordance with the findings of Paper III. The bright Hα emission stars of Flat SED (Table 2, Paper III) fit into this trend.

Table 13. Average Properties of Candidate PMS Stars with Different SED Slopes

SED Slope	$\langle {K}_{s}\rangle$	$\langle {A}_{{\rm{V}}}\rangle$	$\langle {T}_{\mathrm{eff}}\rangle$	$\langle L/{L}_{\odot }\rangle$	$\langle {T}_{\mathrm{bol}}\rangle$	$\langle {L}_{\mathrm{bol}}/{L}_{\odot }\rangle$	N
Primordial (II P)	12.225	2.83	4160	1.02	2634	1.49	46
Evolved (II A)	13.474	2.83	3620	0.69	2460	0.84	80
Evolved (II T)	13.343	2.34	3660	0.34	2378	0.51	29
All Class II	13.124	2.74	3806	0.71	2480	0.96	155

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A most prominent member of the T Tauri star population of the region is the Hα emission star associated with IRAS 02236+7224. Its early G spectral type (Paper III) suggests a mass of ∼2 M_☉. The Omega-Cass images reveal a faint companion at an angular distance of 1 farcs 12 (∼760 au). The IRAC 8 μm image shows a further companion at 4 farcs 3 (3550 au) to the northwest and another one at 4 farcs 9 (4040 au) to the southeast from the primary star (Figure 14, lower right panel).

5. SURFACE DISTRIBUTION OF THE YOUNG STELLAR POPULATION

The positions of all candidate YSOs, identified by infrared color indices, are overplotted on the extinction map of the region, together with ¹³CO and C¹⁸O contours (from Paper I), in Figure 26. More detailed maps of the central regions of the L1340 A, L1340 B, and L1340 C clumps are presented in Figures 27–29, respectively.

**Figure 26.** Surface distribution of the candidate YSOs, identified by infrared colors, overplotted on the visual extinction map of L1340, determined from star counts in the SDSS DR9 (Paper III). Black contours show ¹³CO integrated intensities, drawn at 0.6, 1.2, 1.8,... K km s⁻¹, and the red dot-dashed contour shows the C¹⁸O contour at 0.35 K km s⁻¹. The meaning of the symbols is shown in the lower right corner.
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**Figure 27.** Surface distribution of the candidate YSOs and dense NH₃ cores in a 156 × 12' area of L1340 A, plotted on the IRAC 3.6 μm image of the field.
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**Figure 28.** Surface distribution of the candidate YSOs and dense NH₃ cores in a 20' × 20' area of L1340 B. Symbols are the same as in Figure 27, plus downward-pointing triangles mark submillimeter sources.
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**Figure 29.** Surface distribution of the candidate YSOs and dense NH₃ cores in a 12' × 12' area of L1340 C. Symbols are the same as in Figure 27, plus triangles indicate far-infrared sources detected in the *Herschel* PACS images.
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The surface distribution of the candidate YSOs reveals a rich population of young stars clustered over the clumps L1340 A, B, and C. We constructed surface density maps of the YSOs following the method described by Gutermuth et al. (2005). We determined the r_N(i, j) distance of the Nth nearest star at each (i, j) position of a uniform grid and obtained the local surface density of YSOs at the grid point as $\rho (i,j)=N/\pi {r}_{N}^{2}(i,j)$ . The surface density contour plot, shown in the left panel of Figure 30, was constructed using a 30'' grid and N = 6 and shows the surface densities of Class I+Flat (red dot-dashed contours) and Class II (blue solid contours) sources separately, overlaid on the WISE 12 μm image of L1340. The contour labels indicate the surface densities in star pc⁻² units. The YSO groups associated with the cloud clumps are apparent. Like the three clumps, the associated YSOs show diverse surface structures. The surface distribution in L1340 A suggests a west-to-east progression of star formation. Similarly, in L1340 C, Class I and Class II sources are apparently separated from each other. The largest clump L1340 B is associated with an extended, low surface density population. The right panel of Figure 30 shows a composite surface density distribution of all YSO classes, derived at the same grid points, and using the distance of the twentieth-nearest YSO. The three clusterings, associated with the three clumps, remain apparent in the smoothed surface density map. The area of each YSO group and the number of stars within the surface density contour 2 stars pc⁻² are listed in Table 14.

**Figure 30.** Left: surface density distribution of the young stars, overplotted on the *WISE* 12 μm map of the cloud. Blue contours show the surface density of pre-main-sequence stars, and red contours show that of the Class I + Flat SED sources. Each distribution was computed from the distances of the sixth-nearest stars to the grid points. Right: smoothed, composite surface density distribution of all candidate YSO classes, derived from the distance of the 20th-nearest YSO to the grid points.
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Table 14. Major Properties of the YSO Groups Associated with the Cloud Clumps

Clump	L1340 A	L1340 B	L1340 C	L1340 Total^a
Area (pc²)	5.4	10.8	7.0	90^b
N(Class 0/I)	8	23	14	45
N(Flat)	12	9	6	27
N(Class II)	51	47	50	170
N(Sp ≤ F5)	3	7	1	11
N(total)	74	87	71	253
Mean surface density (stars pc⁻²)	41.1	5.25	13.4	2.8
NII / (NI+NFlat)	2.55	1.47	2.5	2.36
SFE^c	0.17	0.03	0.05	0.03

Notes.

^aStars outside of the surface density contour of 2 stars pc⁻² are also included in this column. ^bTotal area of L1340 with A_V > 1.0 mag (Paper III). ^cStar formation efficiency, assuming average stellar mass of 0.5 M_☉, and taking the clump masses from Paper III.

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5.1. Young Clusters in L1340

To find and characterize clusters in the YSO population of L1340, we examined the projected distances between the stars within the three groups seen in Figure 30. Figure 31 shows the histograms of the nearest neighbor separations for the three groups, separately. The histograms of groups associated with L1340 A and L1340 C show peaks at short spacings, similarly to other nearby SFRs (Gutermuth et al. 2009). On the contrary, no preferred spacing range can be seen in the histogram of L1340 B. The median separations of the YSOs are 0.117, 0.243, and 0.141 pc in L1340 A, B, and C, respectively.

**Figure 31.** Histograms of the nearest neighbor separations for the three clumps of L1340.
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Figure 32 shows the YSO distribution overplotted on the extinction map, and the stars having a neighbor closer than 0.15 pc (≈42'') are marked by underlying black dots. In L1340 A, 75% of the YSO population belongs to this clustered subsystem, while 66% of the YSOs in L1340 C and 34% in L1340 B have neighbors within this distance. We identified four small clusters encircled by the overplotted ellipses. This criterion reveals 56 members of the RNO 7 cluster in L1340 A, including the K-band excess stars identified in the Omega-Cass data. The RNO 9 cluster in L1340 C consists of 1 Class I, 3 flat, and 22 Class II sources, whereas 6 of the 12 members of the cluster associated with IRAS 02276+7225 are Class I/Flat sources. The only small clustering in clump B consists of eight stars, including the bright Class I source RNO 8. The coordinates and sizes of the clusters, identified by the nearest neighbor spacings, and the number of stars within them are listed in Table 15. The sizes are described by the major axis (a) and aspect ratio (AR) of the smallest ellipse encircling the members. The sampling of the members was not homogeneous, since part of L1340 A was not covered by the MIPS observations, whereas the IRAS 02276+7225 cluster is outside of the 4.5 and 8 μm IRAC images. Moreover, eight members of the central core of RNO 7 come from the Omega-Cass observations. For comparison, the last row of Table 15 lists the median values derived for the young cluster sample in our 1 kpc Galactic environment (Gutermuth et al. 2009).

Table 15. Positions, Sizes, and Stellar Contents of the Clusters Embedded in L1340

Object	R.A.(J2000)	Decl.(J2000)	a(pc)^a	AR^b	N(total)	N(Class II)/N(Class I)
RNO 7	02 28 31.2	72 37 34	0.8	1.9	56	2.5
RNO 8	02 30 42.0	72 59 50	0.21	1.17	8	2
RNO 9	02 31 21.6	72 40 08	0.55	1.8	26	5
IRAS 02276+7225	02 32 32.6	72 39 02	0.34	1.48	12	1.0
SSYSC^c median	⋯	⋯	0.39	1.82	26	3.7

Notes.

^aMajor axis of the smallest ellipse containing the member stars. ^bAspect ratio of the same ellipse. ^cA Spitzer Survey of Young Stellar Clusters within 1 kpc of the Sun (Gutermuth et al. 2009).

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5.2. YSO Distribution and the Cloud Structure

The four small, compact clusters identified above comprise nearly half of the candidate YSOs. The distributed population consists of Class II stars scattered widely over low-extinction regions and small groups of a few closely spaced YSOs. An example is the small aggregate marked by a red circle in Figure 32, consisting of Class I, Flat, submillimeter, and strongly reddened Class II sources, and similar in angular size to the knots seen in the extinction map. To demonstrate the connection between the cloud structure and YSO distribution, we present in Figure 33 a multiwavelength view of L1340 B, revealing various aspects of interactions between the cloud and embedded stars. The upper panel of Figure 33 suggests that Class 0/I sources of L1340 B are associated with small-scale dust clumps. The morphology of this image suggests that the filamentary structure, detected at 850 μm, might have been created by past and present winds of the nearby young B- and A-type stars. The middle panel demonstrates the interactions of the intermediate-mass stars with the gas and dust and reveals a diversity of the embedded YSOs. The lower panel reveals that a chain of Class 0/I/Flat sources and two ammonia cores (Paper II) are lined up along a ridge of 850 μm emission, starting with the Class 0 source J022808.60+725904.5 at the southwestern side, and stretching over a projected length of some 3 pc to the Flat SED source 023042.36+730305.1 at the northeastern end. The average separation of the protostars/bright knots along the submillimeter filament, ∼1 farcm 6, corresponds to ∼0.4 pc at 825 pc.

**Figure 33.** Multiwavelength view of the central, 1716 × 93 area of the molecular clump L1340 B. The upper panel shows the positions of the B- to A-type stars (blue star symbols), Class 0/I infrared sources (red dots), flat SED (orange squares), Class II YSOs, ammonia cores (Paper II, green circles), and the contours of 850 μm emission (purple contours, plotted at 30, 60, and 120 Jy beam⁻¹), overplotted on the extinction map. Class I sources associated with tenth-of-parsec-scale density enhancements and a bubble-like cavity, bordered by submillimeter emission around an A-type star, can be seen. The middle panel is a three-color image of the same area, composed of DSS2 blue (blue), *Spitzer* IRAC 8 μm (green), and MIPS 70 μm (red) images. It reveals a bow-shock-like structure in the 8 μm emission around an A-type star and the wispy structure of the diffuse 8 μm emission. Brightness and color diversities of the embedded stars reveal their diverse evolutionary stages and luminosities. Lower panel: three-color image of the same region, composed of the MIPS 24 μm (blue), MIPS 70 μm (green), and SCUBA 800 μm (red) images. The infrared sources lined up along the ∼2 pc long, cold filamentary structure.
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Linear configurations in the distribution of protostars are thought to result from fragmentation of dense molecular filaments (e.g., Teixeira et al. 2006). The separation of protostars along the filament is of the order of the Jeans length. Temperatures and densities derived from the ammonia mapping of L1340 (from Paper II) suggest a Jeans length of ∼0.14 pc for the dense cores of L1340. The wide separation of the protostars along the submillimeter filament of L1340 B, as well as the large average spacing of the nearest neighbors throughout the clump, suggests a higher temperature of the ambient medium. The NH₃ cores are probably the coldest regions of the cloud, embedded in a warmer gas, heated by the nearby B- and A-type stars.

Another conspicuous linear feature is the J-shaped configuration of YSOs in L1340 C (the IRAS 02276+7225 cluster; Figure 29). The average separation of the objects within that chain is 27 farcs 9, corresponding to 0.11 pc at a distance of 825 pc. The total length of the chain is some 0.9 pc, suggesting that these stars have been formed from cores of ∼0.1 pc in diameter. This coincides with the average size of the ammonia cores studied in Paper II and is the same as the Jeans length at T_kin ≈ 12.5 K and ${n}_{{{\rm{H}}}_{2}}\approx 1.29\times {10}^{4}$ cm⁻³, resulting from the NH₃ observations. The cloud structure, underlying the observed distribution of the protostars, can be seen in the distribution of the cold dust, revealed by the Herschel SPIRE images (Figure 7).

6. STAR FORMATION IN L1340

At a distance of 825 pc and a latitude of 11 fdg 5, L1340 is situated some 160 pc above the Galactic plane, in a low-density outer region of the molecular disk of our Galaxy. (The Swan is floating on the surface of the Galactic molecular disk.) The average hydrogen column densities of the three molecular clumps are about 2.5 × 10²¹ cm⁻², slightly lower than the mean column density of 4.38 × 10²¹ cm⁻², obtained by Lundquist et al. (2015) for IMSFRs in the outer Galaxy. The extinction map of L1340 (Paper III) reveals a shallow molecular cloud, spotted with dense knots of a characteristic size of a few arcminutes (∼0.5 pc). YSOs are grouped on similar angular scales, and Class 0/I–Flat sources appear closely associated with extinction knots (see Figure 33), suggesting that star formation occurs in small groups, consisting of a few stars, and scattered over the surface of the cloud. The most massive star in L1340 is an optically visible B4-type star of some 5 M_☉, whereas the YSOs revealed by our present survey are in the 0.07 ≲ M/M_☉ ≲ 2.5 mass interval.

The number of embedded sources, as well as their ratio to the more evolved pre-main-sequence stars in an SFR, is an indicator of evolutionary state. Myers (2012) established relations between Class II/Class I number ratios, as well as ages and birthrates of young stellar clusters, assuming a constant protostellar birthrate. The Class II/Class I ratio (Table 14) suggests an age of 10⁶ yr and a birthrate of 200–300 protostars Myr^–1. The three clumps of L1340 differ from each other in several respects. The effects of young intermediate-mass stars on the environment are conspicuous in L1340 B. The wispy structure of the 8 μm emission, the bow-shock-like structure associated with an A2-type star, and the double-peaked CO lines at the positions of the Planck Cold Clumps (Wu et al. 2012) associated with L1340 suggest violent swirling of the gas in this region. The low surface density of YSOs, compared to the other clumps of the cloud, indicates that the prestellar gas in L1340 B had higher temperature and lower density than in L1340 A and L1340 C, owing to the heating from the ambient B-type stars. The higher proportion of protostars in L1340 B (NII/(NI+NFlat) = 1.47) suggests that the average age of the YSO sample is lower in this clump than in the others. SFRs like L1340 B are probably more transient structures than centrally condensed young embedded clusters. Pfalzner et al. (2015) have found that only clusters and associations with initial central surface densities exceeding a few ×10³ M_☉ pc⁻² will be detected as clusters at ages longer than 5 Myr.

Assuming an average mass of 0.5 M_☉ for each candidate YSO, and including the intermediate-mass stars, discussed in Paper III, we find the star formation efficiencies (SFE = ${M}_{\mathrm{star}}/({M}_{\mathrm{star}}+{M}_{\mathrm{cloud}}$ ) listed in Table 14 for the three clumps of L1340. It can be seen that while some 17% of the gas turned into stars in L1340 A, the SFE is only 3% for L1340 B and also for the whole cloud. The actual SFEs are probably somewhat higher, since the low-mass diskless YSO population of L1340 is still unknown.

6.1. Comparison with Other Star-forming Regions

Comparison of our target cloud with IMSFRs, located in similar environments, may help to understand the interstellar processes, leading to star formation near the outer boundaries of the Galactic molecular disk. The short expected lifetime of L1340 (probably ≪5 Myr) suggests that similar SFRs may be rare in our Galactic neighborhood. A sample of 50 IMSFRs, studied by Arvidsson et al. (2010), contains objects similar in stellar content and total mass to L1340. Most of them are, however, more distant, and thus their detailed structures are still unrevealed. The Spitzer sample of young clusters in our Galactic neighborhood (SSYSC; Gutermuth et al. 2009) also contains several IMSFRs. Comparison of our results with several properties of this sample of young clusters is shown in Table 15. It suggests that the clusters identified in the YSO population of L1340 are similar in size, shape, and stellar content to the SSYSC average. The distribution of the projected YSO separations, however, suggests that the mode of star formation in L1340 B is quite atypical. The median nearest neighbor separations are significantly smaller in each of the SSYSC clusters than in L1340 B. Another atypical feature of L1340 is that conspicuous YSO groups are being formed in the smaller clumps, whereas the largest clump, associated with the highest-luminosity stars of the region, has a fragmented structure, associated with tiny groups of YSOs, scattered over the area of the clump.

A few IMSFRs in our 1 kpc Galactic environment are also located at latitudes around 10° or higher and are apparently not associated with giant molecular clouds. Well-known examples are NGC 7023 and NGC 7129, both located more than 100 pc above the Galactic plane, and forming small clusters with the brightest stars of B3 type. These regions may have star-forming histories similar to L1340. Expanding supershells could create conditions of star formation at intermediate Galactic latitudes. Apparently none of these SFRs are associated with supershells; thus, some other process, such as infall of high-velocity clouds or Kelvin–Helmholtz instabilities arising at the shearing surface between gas layers of different velocities, might have compressed the gas.

7. CONCLUSIONS

We identified some 250 candidate YSOs associated with the moderate-mass (∼3700 M_☉; Paper III) molecular cloud L1340, based on Spitzer, AllWISE mid-infrared, and Omega-Cass near-infrared data, using various published color criteria. Supplemented with our measurements on the Herschel PACS 100 and 160 μm images and publicly available photometric data, we constructed SEDs and classified 8 candidate Class 0, 37 Class I, 27 Flat SED, and 170 Class II sources. Based on the SEDs, we derived extinctions and spectral types for the Class II sources and plotted them on the HRD. The HRD suggests a mass interval of 0.07–2.5 M_☉ for the CTTSs of our sample.

We identified new Herbig–Haro objects, associated with the Class 0 protostar SSTSL2 022808.60+725904.5 in the Spitzer images. The Spitzer data reveal that the bright IRAS source 02249+7230 is a binary protostar associated with Herbig–Haro objects. The Spitzer data also suggest that the probable driving source of HH 488 is a Class 0 protostar, SSTSL2 J022820.81+723500.5. The projected length of HH 488 is some 1.3 pc.

The Omega-Cass JHK data resulted in eight new candidate members of RNO 7 and revealed a close companion of its brighest member, IRAS 02236+7224. The Spitzer 8 μm image revealed two further wide companions of this intermediate-mass T Tauri star.

The surface density distribution of YSOs shows three groups, associated with the three major molecular clumps of L1340, each consisting of ≲100 members, including both pre-main-sequence stars and embedded protostars. Based on the distribution of nearest neighbor separations, we identified four small clusters in the cloud, the RNO 7 cluster in L1340 A, RNO 8 in L1340 B, and RNO 9 and IRAS 02276+7225 in L1340 C. Filamentary configurations of the protostars follow the distribution of the cold dust, traced by SCUBA and Herschel observations. The efficiency of the star formation in L1340 is some 3%. Our results demonstrate that L1340 is a prolific SFR of our Galactic environment in which several specific properties of the intermediate-mass mode of star formation can be studied in detail. The distribution of dense gas and YSOs suggests that SFRs like L1340 are short-lived, transient objects.

This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. This research utilized observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Our research has benefited from the VizieR catalog access tool, CDS, Strasbourg, France. Financial support from the Hungarian OTKA grant K81966 and K101393 is acknowledged. This work was partly supported by the Momentum grant of the MTA CSFK Lendület Disk Research Group.

APPENDIX: UBVR_CI_CJHK_s PHOTOMETRIC DATA OF THE CLASS II YSOs

We list UBVR_CI_C magnitudes, transformed from the SDSS data, and 2MASS JHK_s magnitudes of the color-selected candidate Class II young stars associated with L1340 in Table A1, excluding the Hα emission stars, whose data are given in Paper III.

Table A1. UBVR ${}_{{\rm{C}}}$ I ${}_{{\rm{C}}}$ JHK ${}_{s}$ magnitudes of the Class II candidate YSOs of L1340, not detected as H $\alpha$ emission stars

Id	U dU	B dB	V dV	R ${}_{{\rm{C}}}$ dR ${}_{{\rm{C}}}$	I ${}_{{\rm{C}}}$ dI ${}_{{\rm{C}}}$	J dJ	H dH	K ${}_{s}$ dK ${}_{s}$
022654.73+724040.8	23.541 1.553	20.627 0.019	18.671 0.019	17.371 0.011	15.906 0.010	14.338 0.031	13.461 0.038	13.229 0.035
022659.03+725716.0	21.511 0.379	20.246 0.015	18.480 0.015	17.332 0.011	16.004 0.011	14.130 0.047	13.312 0.050	13.074 0.042
022659.35+725714.2	21.782 0.379	20.246 0.015	18.483 0.015	17.301 0.011	16.022 0.011	14.130 0.047	13.312 0.050	13.074 0.042
022705.53+724116.7	16.228 0.010	15.288 0.007	13.568 0.007	13.443 0.014	13.715 0.019	9.901 0.022	9.084 0.051	8.579 0.020
022713.95+723913.8	17.786 0.020	16.778 0.007	15.503 0.007	14.705 0.007	13.922 0.008	12.876 0.025	12.157 0.030	11.938 0.022
022720.91+723825.6	22.313 0.383	21.114 0.025	19.483 0.025	18.286 0.018	16.724 0.015	14.696 0.035	13.654 0.034	13.068 0.027
022722.72+730913.8	22.934 0.822	21.675 0.038	19.971 0.038	18.683 0.023	17.014 0.015	15.287 0.045	14.498 0.060	14.214 0.068
022725.68+723911.1	18.446 0.028	17.294 0.007	15.924 0.007	15.065 0.008	14.221 0.008	13.167 0.024	12.234 0.030	11.526 0.016
022753.10+723933.2	23.736 0.882	22.502 0.067	20.668 0.067	19.221 0.033	17.249 0.019	15.289 0.041	14.537 0.054	14.183 0.051
022756.40+723833.2	24.444 1.111	23.094 0.120	21.467 0.120	20.072 0.068	17.942 0.029	15.707 0.072	14.849 0.065	14.383 0.074
022807.66+723955.9	20.544 0.096	19.068 0.009	17.337 0.009	16.221 0.008	15.095 0.009	12.865 0.022	11.997 0.029	11.578 0.019
022808.36+723718.1	24.899 1.058	24.015 0.225	21.787 0.225	20.189 0.072	18.017 0.032	15.733 0.108	15.086 0.118	14.708 0.110
022809.45+723845.6^a^,^b	24.045 1.530	25.828 0.835	24.461 0.835	23.163 0.822	⋯	17.152 0.217	16.175 0.214	15.146 0.130
022812.42+724207.4	24.716 1.106	23.783 0.201	22.017 0.201	20.494 0.095	18.169 0.032	15.129 0.046	14.375 0.051	14.043 0.049
022815.41+723649.0	25.383 1.273	24.440 0.332	22.394 0.332	20.824 0.132	18.408 0.043	15.994 0.072	15.186 0.096	14.971 0.112
022818.15+723820.8	25.159 1.092	25.062 0.465	22.975 0.465	21.289 0.192	18.447 0.041	15.543 0.059	14.813 0.076	14.292 0.068
022822.40+723808.4	23.046 0.730	23.520 0.149	21.288 0.149	19.888 0.049	⋯	15.036 ⋯	15.988 0.168	14.635 0.089
022826.25+723745.4	25.583 1.127	24.650 0.344	22.581 0.344	20.932 0.136	18.309 0.037	15.661 0.053	14.909 0.066	14.273 0.059
022827.25+723853.4	20.854 0.136	19.420 0.010	17.759 0.010	16.644 0.009	15.377 0.009	13.243 0.025	12.121 0.030	11.573 0.020
022830.47+723724.2^a^,^b	22.925 0.974	23.002 0.130	21.041 0.130	19.808 0.059	⋯	16.753 0.168	15.627 0.139	14.781 0.102
022832.38+724301.7	18.445 0.027	17.338 0.007	15.980 0.007	15.130 0.008	14.290 0.008	13.311 0.027	12.392 0.028	11.874 0.020
022833.91+724021.8	23.968 0.748	23.880 0.253	22.259 0.253	20.787 0.137	18.428 0.042	16.322 0.096	15.283 0.100	14.958 0.107
022842.02+725719.1	23.346 0.520	22.825 0.095	21.135 0.095	19.846 0.047	17.872 0.027	15.717 0.063	15.092 0.091	14.801 0.095
022845.94+723830.8	23.995 0.970	22.173 0.045	19.963 0.045	18.484 0.019	16.909 0.015	14.619 0.028	13.390 0.033	12.816 0.022
022851.59+723633.6	24.199 0.887	23.238 0.113	21.253 0.113	19.741 0.048	17.745 0.025	15.312 0.048	14.282 0.043	13.771 0.049
022902.40+723729.6^b	23.939 1.613	25.611 0.845	23.448 0.845	21.699 0.394	18.832 0.074	15.729 0.088	14.815 0.071	14.348 0.071
022904.71+730131.0	23.018 0.725	24.767 0.409	22.782 0.409	21.397 0.162	19.320 0.082	15.643 0.074	13.537 0.057	12.436 0.039
022910.68+723902.3^a^,^b	25.083 1.642	24.017 0.462	22.225 0.462	21.055 0.245	⋯	17.025 0.216	15.059 0.079	14.350 0.068
022914.45+725503.6	24.660 1.312	24.463 0.434	22.852 0.434	21.402 0.238	18.599 0.054	15.928 0.085	15.130 0.084	14.687 0.099
022916.14+731400.6	24.513 0.681	24.783 0.392	22.406 0.392	20.725 0.129	18.390 0.040	15.582 0.066	14.526 0.047	13.990 0.062
022937.11+725053.3	18.334 0.024	17.140 0.007	15.646 0.007	14.695 0.008	13.723 0.008	12.277 0.022	11.490 0.030	11.088 0.019
022941.28+725932.4	24.699 1.150	23.493 0.146	21.436 0.146	19.874 0.053	17.834 0.027	15.614 0.062	14.690 0.060	14.249 0.061
022941.91+725201.7	24.556 0.801	23.807 0.172	21.523 0.172	19.785 0.051	17.493 0.021	14.897 0.038	14.211 0.047	13.775 0.036
022942.26+725558.6	23.550 0.988	21.976 0.045	20.177 0.045	18.752 0.023	16.793 0.015	14.812 0.040	14.091 0.050	13.849 0.047
022948.77+731326.9	23.362 1.018	22.070 0.050	20.287 0.050	18.885 0.028	16.964 0.015	14.940 0.032	14.241 0.047	13.949 0.051
022950.37+730543.6	23.646 0.624	22.947 0.100	21.138 0.100	19.727 0.047	17.809 0.027	15.861 0.073	15.271 0.101	14.764 0.099
022951.13+731408.0	26.132 1.215	26.686 0.686	23.889 0.686	22.039 0.401	19.683 0.114	16.308 0.099	15.486 0.119	14.637 0.089
022953.40+730018.6	24.507 0.936	24.034 0.238	22.177 0.238	20.650 0.101	18.484 0.042	16.419 0.116	15.565 0.120	15.157 0.139
022958.24+723234.4	24.315 1.501	22.524 0.071	20.510 0.071	19.005 0.030	17.068 0.016	14.816 0.039	13.921 0.041	13.443 0.027
023001.32+725138.8	21.859 0.337	20.307 0.016	18.587 0.016	17.237 0.011	15.351 0.009	13.301 0.031	12.520 0.034	12.203 0.027
023001.93+731237.9	25.352 1.263	25.915 0.744	23.967 0.744	22.095 0.472	19.013 0.065	15.723 0.057	14.898 0.067	14.423 0.065
023002.85+723643.4	23.569 0.536	22.976 0.097	20.881 0.097	19.417 0.038	17.502 0.021	15.269 0.051	14.189 0.048	13.735 0.046
023003.62+730435.0	19.381 0.045	18.119 0.008	16.549 0.008	15.540 0.008	14.518 0.008	13.055 0.031	12.302 0.034	12.030 0.022
023008.63+725243.2	25.368 1.491	24.501 0.373	22.192 0.373	20.431 0.109	18.062 0.036	15.858 0.075	15.069 0.079	14.599 0.084
023011.32+725020.3	25.431 1.274	24.818 0.435	22.893 0.435	21.383 0.184	19.222 0.071	16.650 0.146	15.599 0.114	14.932 0.108
023013.55+730211.2	23.748 0.791	23.134 0.124	21.539 0.124	20.136 0.068	17.979 0.030	15.790 0.077	15.230 0.086	14.767 0.097
023021.33+723926.5	21.038 0.084	20.956 0.024	19.369 0.024	18.289 0.018	16.978 0.015	15.007 0.043	14.082 0.047	13.450 0.041
023027.76+724002.9	22.656 0.423	21.636 0.034	19.716 0.034	18.383 0.019	16.830 0.015	14.702 0.031	13.639 0.037	12.883 0.024
023029.60+725048.0	26.685 1.216	25.493 0.703	23.155 0.703	21.360 0.237	18.935 0.069	15.983 0.083	14.931 0.070	14.632 0.091
023031.45+730023.6^b	23.046 0.730	23.520 0.149	21.288 0.149	19.888 0.049	⋯	15.969 0.077	14.904 0.062	14.331 0.072
023036.26+725550.5	23.629 0.575	23.345 0.145	21.671 0.145	20.547 0.079	19.281 0.088	16.528 0.156	14.846 0.092	13.939 0.059
023036.44+725554.5	25.545 1.270	25.066 0.462	22.821 0.462	21.297 0.153	19.539 0.098	16.579 0.120	15.220 0.091	14.516 0.075
023038.71+725941.2	22.416 1.093	22.024 0.134	21.806 0.134	21.426 0.176	20.024 0.174	16.440 0.109	15.578 0.116	14.878 0.112
023042.66+723638.9	22.415 0.455	21.076 0.024	19.201 0.024	17.835 0.014	15.891 0.010	13.872 0.024	13.040 0.030	12.644 0.019
023043.12+724834.4	23.452 0.690	22.577 0.074	20.833 0.074	19.646 0.039	18.099 0.031	15.726 0.070	14.392 0.045	13.682 0.031
023043.40+730451.3	24.232 0.723	24.578 0.417	22.651 0.417	20.998 0.177	18.556 0.052	16.408 0.118	15.494 0.108	15.113 0.124
023043.85+730647.2	18.713 0.031	17.347 0.007	15.787 0.007	14.828 0.008	13.858 0.008	12.615 0.027	11.743 0.030	11.520 0.021
023047.01+730233.2	23.825 1.063	22.292 0.059	20.498 0.059	19.084 0.030	17.146 0.018	14.998 0.046	14.305 0.037	13.942 0.049
023055.66+723449.8	25.144 1.269	23.447 0.147	21.378 0.147	19.852 0.057	17.707 0.024	15.682 0.096	14.840 0.081	14.518 0.088
023100.74+723555.3	23.810 0.663	23.298 0.133	21.266 0.133	19.763 0.054	17.554 0.021	15.032 0.048	14.207 0.047	13.641 0.045
023102.68+723844.4	27.885 1.702	26.830 0.689	23.269 0.689	20.922 0.161	18.344 0.038	15.632 0.063	14.687 0.072	14.126 0.060
023103.83+725503.0	25.514 1.228	24.678 0.346	22.377 0.346	20.588 0.097	17.879 0.027	15.363 0.050	14.750 0.058	14.396 0.067
023104.03+723446.1	25.069 1.410	25.026 0.535	23.018 0.535	21.339 0.232	18.568 0.043	16.130 0.105	15.078 0.079	14.640 0.083
023104.33+723836.1	24.972 1.428	24.073 0.228	21.797 0.228	20.095 0.075	17.900 0.026	15.362 0.053	14.422 0.057	13.988 0.047
023105.58+730545.1	23.052 1.003	20.742 0.019	18.916 0.019	17.670 0.012	16.303 0.012	14.723 0.040	13.970 0.037	13.677 0.041
023113.07+725955.4	24.997 1.096	23.842 0.221	22.065 0.221	20.698 0.103	18.572 0.049	16.283 0.107	15.784 0.151	15.462 0.182
023115.90+723841.1	⋯	⋯	⋯	⋯	⋯	16.250 0.154	14.198 0.066	12.713 0.033
023117.30+724036.4	25.251 0.719	23.286 0.155	21.623 0.155	20.266 0.088	18.245 0.035	16.093 0.088	15.196 0.074	14.635 0.082
023117.41+724149.1^b	24.883 1.782	23.849 0.260	22.029 0.260	20.606 0.128	18.583 0.048	16.409 0.099	15.544 0.116	15.326 0.147
023121.41+723802.6	24.311 1.119	25.415 0.764	23.842 0.764	22.454 0.581	19.787 0.118	16.617 0.135	16.016 0.178	15.659 0.247
023123.89+724056.0	26.490 0.899	24.785 0.509	22.680 0.509	20.996 0.204	18.612 0.050	16.020 0.070	15.279 0.087	15.193 0.125
023126.87+724242.9	23.118 0.532	21.889 0.039	19.708 0.039	18.262 0.017	16.735 0.013	14.603 0.029	13.523 0.032	13.145 0.031
023128.07+723934.5^b	24.176 3.097	26.410 1.017	26.650 1.017	25.958 1.956	22.055 2.526	16.595 0.138	14.416 0.079	12.851 0.030
023131.29+724020.2	⋯	⋯	⋯	⋯	⋯	17.585 ⋯	15.848 0.147	14.171 0.066
023134.70+723356.7	21.548 0.358	20.305 0.015	18.443 0.015	17.238 0.010	15.882 0.010	14.300 0.039	13.428 0.039	13.065 0.040
023136.55+724144.8	24.390 1.077	23.515 0.147	21.287 0.147	19.835 0.052	18.038 0.029	15.509 0.054	14.230 0.051	13.602 0.043
023140.47+724152.4	24.470 0.802	23.928 0.196	21.559 0.196	19.860 0.059	17.435 0.020	14.685 0.055	13.552 0.047	13.068 0.039
023140.50+724247.0	25.032 1.708	25.572 0.835	24.090 0.835	22.454 0.724	19.444 0.082	16.226 0.097	14.923 0.075	14.642 0.090
023141.65+730037.7	22.815 0.486	21.225 0.025	19.237 0.025	17.913 0.013	16.520 0.014	15.213 0.041	14.031 0.042	13.421 0.040
023149.84+723848.1	⋯	⋯	⋯	⋯	⋯	18.655 ⋯	15.574 0.114	13.165 0.030
023153.88+724317.5^b	26.903 0.850	23.390 0.499	21.074 0.499	19.494 0.152	17.419 0.058	15.893 0.085	14.478 0.057	13.699 0.041
023157.79+724023.7	24.005 2.117	24.992 1.182	24.843 1.182	24.002 1.376	20.788 0.307	16.888 0.182	16.038 0.186	15.111 0.129
023158.57+724034.6	26.913 1.662	26.174 0.780	23.577 0.780	21.605 0.332	19.138 0.068	15.923 0.093	14.283 0.048	13.534 0.038
023219.76+723844.9	⋯	⋯	⋯	⋯	⋯	17.535 ⋯	15.823 0.143	14.475 0.074
023221.97+724029.4	⋯	⋯	⋯	⋯	⋯	⋯	⋯	⋯
023231.96+723741.9	25.575 1.507	25.460 0.655	22.960 0.655	21.206 0.210	18.965 0.064	15.461 0.052	13.945 0.041	13.276 0.030
023248.83+724635.4^b	25.350 1.079	23.405 0.297	21.735 0.297	20.589 0.171	19.258 0.138	17.114 0.228	16.067 0.198	15.355 0.158
023331.52+724655.4	26.812 1.097	25.053 0.627	22.612 0.627	21.201 0.202	20.003 0.192	⋯	⋯	⋯
023347.95+724635.7	18.934 0.043	17.778 0.008	16.482 0.008	15.705 0.008	14.956 0.009	14.034 0.027	13.399 0.032	13.326 0.031
023453.91+724646.3	23.640 0.749	22.880 0.097	21.137 0.097	19.761 0.047	17.812 0.025	15.599 0.063	14.857 0.058	14.255 0.061

UBVR ${}_{{\rm{C}}}$ I ${}_{{\rm{C}}}$ magnitudes were tarnsformed from the SDSS data, using the equations published by Ivezić et al. (2007) (for BVR ${}_{{\rm{C}}}$ I ${}_{{\rm{C}}}$ ) and Jordi et al. (2006) (for U). JHK ${}_{{\rm{s}}}$ magnitudes are from the 2MASS All Sky Catalog of Point Sources (Cutri et al. 2003).

^aUBVRI magnitudes of this star is transformed from the SDSS DR7 data. ^bSDSS classifies this object as a galaxy.

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THE YOUNG STELLAR POPULATION OF LYNDS 1340. AN INFRARED VIEW

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ABSTRACT

1. INTRODUCTION

2. DATA

2.1. Spitzer Data

2.2. High Angular Resolution Near-infrared Imaging

2.3. Supplementary Data

3. INFRARED APPEARANCE OF L1340: THE SWAN NEBULA

4. YSOs IN L1340

4.1. Spitzer Sources

4.1.1. SED-based Classification

4.1.2. Estimating Foreground Extinction

4.1.3. Submillimeter, Far-infrared, and Optical Counterparts

4.1.4. Bolometric Temperatures and Luminosities

4.2. New Candidate Members of RNO 7 in the Omega-Cass Data

4.3. AllWISE Sources

4.4. Embedded Protostars and Herbig–Haro Objects in L1340

4.4.1. Candidate Class 0 Sources

4.4.2. Class I Protostars Associated with IRAS Sources

4.5. Classical T Tauri Stars

5. SURFACE DISTRIBUTION OF THE YOUNG STELLAR POPULATION

5.1. Young Clusters in L1340

5.2. YSO Distribution and the Cloud Structure

6. STAR FORMATION IN L1340

6.1. Comparison with Other Star-forming Regions

7. CONCLUSIONS

APPENDIX: UBVR_CI_CJHK_s PHOTOMETRIC DATA OF THE CLASS II YSOs

THE YOUNG STELLAR POPULATION OF LYNDS 1340. AN INFRARED VIEW

Article metrics

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Share this article

Author e-mails

Author affiliations

ORCID iDs

Dates

ABSTRACT

1. INTRODUCTION

2. DATA

2.1. Spitzer Data

2.2. High Angular Resolution Near-infrared Imaging

2.3. Supplementary Data

3. INFRARED APPEARANCE OF L1340: THE SWAN NEBULA

4. YSOs IN L1340

4.1. Spitzer Sources

4.1.1. SED-based Classification

4.1.2. Estimating Foreground Extinction

4.1.3. Submillimeter, Far-infrared, and Optical Counterparts

4.1.4. Bolometric Temperatures and Luminosities

4.2. New Candidate Members of RNO 7 in the Omega-Cass Data

4.3. AllWISE Sources

4.4. Embedded Protostars and Herbig–Haro Objects in L1340

4.4.1. Candidate Class 0 Sources

4.4.2. Class I Protostars Associated with IRAS Sources

4.5. Classical T Tauri Stars

5. SURFACE DISTRIBUTION OF THE YOUNG STELLAR POPULATION

5.1. Young Clusters in L1340

5.2. YSO Distribution and the Cloud Structure

6. STAR FORMATION IN L1340

6.1. Comparison with Other Star-forming Regions

7. CONCLUSIONS

APPENDIX: UBVRCICJHKs PHOTOMETRIC DATA OF THE CLASS II YSOs

APPENDIX: UBVR_CI_CJHK_s PHOTOMETRIC DATA OF THE CLASS II YSOs