Table of contents

We present the results of a detailed spectroscopic study of the long-period (P = 0.856 days) RR Lyrae star, KP Cyg. We derived abundances of many chemical elements including the light species, iron-group elements and elements of the s -processes. Most RR Lyrae stars with periods longer than 0.7 days are metal-deficient objects. Surprisingly, our results show that KP Cyg is very metal rich ([Fe/H] = +0.18 ± 0.23). By comparison with a number of short-period (P = 1 ∼ 6 days), metal-rich CWB stars, we suggest that KP Cyg may be a very short-period CWB star (BL Her star) rather than an RR Lyrae star. As seen in some CWB stars, KP Cyg shows strong excesses of carbon and nitrogen in its atmosphere. This indicates that the surface of KP Cyg has been polluted by material that has undergone helium burning (to enhance carbon) and proton capture (to transform carbon into nitrogen). We also note that UY CrB, whose period is 0.929 days, also shows an enhancement of C and N, and that two carbon Cepheids of short period, V553 Cen and RT TrA, show similar excesses of carbon and nitrogen.

We provide precise J2000, epoch 2000 coordinates, and cross-identifications to sources in the 2MASS Point Source Catalog for nearly all stars in the Gliese, Gliese-Jahreiss, and Woolley catalogs of nearby stars. The only Gliese objects where we were not successful are two Gliese sources that are actually QSOs; two proposed companions to brighter stars, which we believe do not exist; four stars included in one of the catalogs but identified there as only optical companions; one probable plate flaw; and two stars that simply remain unrecovered. For the 4251 recovered stars, 2693 have coordinates based on Hipparcos positions, 1549 have coordinates based on 2MASS data, and 9 have positions from other astrometric sources. All positions have been calculated at epoch 2000 using proper motions from the literature, which are also given here.

Absolute spectrophotometry, high-resolution echelle spectroscopy, and BVR_CI_C photometry were obtained to monitor and study the outburst evolution of Nova Aql 2009. When discovered, it was setting near evening twilight, and this prevented the observations from extending past the optically thick phase. The evolution has been particularly smooth, with the V-band maximum being reached on 2009 December 17.2 at 9.90 mag. The B-band maximum preceded the I_C-band maximum by 1 day, consistent with an initial fireball expansion. The reddening is high, E_B-V = 1.35, and the distance is d = 5.0 kpc, for a height above the Galactic plane of z = 180 pc. The decline times of and days qualify Nova Aql 2009 as a very fast nova. The minimum outburst amplitude (set by the magnitude limit of preoutburst SDSS-II survey images) has been ΔR_C≥12.5 mag. The spectral evolution has been typical of a Fe II-type nova, with an ejecta expansion velocity of ∼915 km s^-1. The combination of a very fast decline with a slow ejection velocity sets Nova Aql 2009 apart from the bulk of other novae. The evolution in absolute intensity of the various emission lines was derived, and the time of their maximum flux determined. The Fe II emission reached its maximum value before , Hα around , and O I 8446 (excited by Bowen fluorescence from Lyβ) halfway between and . The oxygen mass in the ejecta is calculated to be 2 × 10^-5 M_⊙ from analysis of [O I] lines.

Correlations between stellar properties and the occurrence rate of exoplanets can be used to inform the target selection of future planet-search efforts and provide valuable clues about the planet-formation process. We analyze a sample of 1266 stars drawn from the California Planet Survey targets to determine the empirical functional form describing the likelihood of a star harboring a giant planet as a function of its mass and metallicity. Our stellar sample ranges from M dwarfs with masses as low as 0.2 M_⊙ to intermediate-mass subgiants with masses as high as 1.9 M_⊙. In agreement with previous studies, our sample exhibits a planet-metallicity correlation at all stellar masses; the fraction of stars that harbor giant planets scales as f ∝ 10^1.2[Fe/H]. We can rule out a flat metallicity relationship among our evolved stars (at 98% confidence), which argues that the high metallicities of stars with planets is not likely due to convective envelope "pollution." Our data also rule out a constant planet occurrence rate for [Fe/H] < 0, indicating that giant planets continue to become rarer at sub-Solar metallicities. We also find that planet occurrence increases with stellar mass (f ∝ M_⋆), characterized by a rise from 3% around M dwarfs (0.5 M_⊙) to 14% around A stars (2 M_⊙), at Solar metallicity. We argue that the correlation between stellar properties and giant planet occurrence is strong supporting evidence of the core-accretion model of planet formation.

Extreme adaptive optics systems (XAO) dedicated to the search for extrasolar planets are currently being developed for 8–10 m telescopes. The high-order test bench (HOT) is a high-contrast imaging adaptive optics bench developed at the European Southern Observatory to test and optimize different techniques and technologies (e.g., wavefront sensors, coronagraphs, speckle calibration methods, image postprocessing). It reproduces realistic conditions at a telescope (e.g., Very Large Telescope, VLT), including a turbulence generator, a high-order adaptive optics system, and a near-IR coronagraph. We discuss the results of XAO coronagraphy obtained in the laboratory in the context of imminent planet-finder instruments (e.g., SPHERE, GPI, and HiCIAO). In particular, results obtained with HOT will be discussed and compared with contrast goals of the near-IR camera of SPHERE. Under a generated dynamical turbulence of 0.5'' seeing, which is efficiently corrected by the XAO system to an H-band Strehl ratio above 90%, and combined with a near-IR coronagraph, we demonstrate contrasts of 5 × 10^-5 at 0.1'', and 4.5 × 10^-6 at 0.5''. Contrasts were obtained using differential imaging techniques by sequentially taking either a series of two closely-spaced narrowband filter images in H band centered around 1.6 μm, or two images with orthogonal polarization states. Results obtained in the laboratory are in good agreement with the contrast goals of SPHERE, which provides confidence in the expected performance of this class of instruments.

A prototype of a low-cost adaptive optics (AO) system has been developed at the Instituto de Astrofisica de Andalucia (CSIC) and tested at the 2.2 m telescope of the Calar Alto Observatory. We present here the status of the project, which includes the image stabilization system and compensation of high-order wavefront aberrations with a membrane-deformable mirror. The image stabilization system consists of a magnet-driven tip-tilt mirror. The higher-order compensation system comprises a Shack-Hartmann sensor, a membrane-deformable mirror with 39 actuators, and the control computer, which allows operations up to 420 Hz in closed-loop mode. We have successfully closed the high-order AO loop on natural guide stars. An improvement of 4 times in terms of FWHM was achieved. The description and the results obtained on the sky are presented in this article.

As the quality and quantity of astrophysical data continue to improve, the precision with which certain astrophysical events can be timed becomes limited not by the data themselves, but by the manner, standard, and uniformity with which time itself is referenced. While some areas of astronomy (most notably pulsar studies) have required absolute time stamps with precisions of considerably better than 1 minute for many decades, recently new areas have crossed into this regime. In particular, in the exoplanet community, we have found that the (typically unspecified) time standards adopted by various groups can differ by as much as a minute. Left uncorrected, this ambiguity may be mistaken for transit timing variations and bias eccentricity measurements. We argue that, since the commonly-used Julian Date, as well as its heliocentric and barycentric counterparts, can be specified in several time standards, it is imperative that their time standards always be reported when accuracies of 1 minute are required. We summarize the rationale behind our recommendation to quote the site arrival time, in addition to using BJD_TDB, the Barycentric Julian Date in the Barycentric Dynamical Time standard for any astrophysical event. The BJD_TDB is the most practical absolute time stamp for extraterrestrial phenomena, and is ultimately limited by the properties of the target system. We compile a general summary of factors that must be considered in order to achieve timing precisions ranging from 15 minutes to 1 µs. Finally, we provide software tools that, in principal, allow one to calculate BJD_TDB to a precision of 1 μs for any target from anywhere on Earth or from any spacecraft.

We present the simage software suite for the simulation of artificial extragalactic images, based empirically around real observations of the Hubble Ultra Deep Field. The simulations reproduce galaxies with realistic and complex morphologies via the modeling of UDF galaxies as shapelets. Images can be created in the B, V, i and z bands for both space- and ground-based telescopes and instruments. The simulated images can be produced for any required field size, exposure time, PSF, telescope mirror size, pixel resolution, field star density, and a variety of detector noise sources. It has the capability to create images with either a predetermined number of galaxies, or one calibrated to the number counts of preexisting data sets such as the HST COSMOS survey. In addition, simple options are included to add a known weak gravitational lensing signal (both shear and flexion) to the simulated images. The software is available in IDL and can be freely downloaded for scientific, developmental, and teaching purposes.

The US astronomical research output during the past 50 yr has been growing at 6 times the population increase and we wonder whether that ratio can continue. I counted pages of the AJ and ApJ for the past 50 yr, and corrected them for changes in format, foreign input, online contributions, and population increases. For the combined two journals, the American astronomical output is still increasing at a current 128 pages per million people. The same is true for UK contributions to the MNRAS, except that those lag behind the US by 10 yr. For Europe I did not want to dilute the contributions in A&A from the major producers with those of the countries still developing major astronomical centers. Therefore I counted pages for France, Germany, Italy, and the Netherlands (FGIN) only. However, Europeans still publish many of their articles in MNRAS, in particular, and ApJ. Counting FGIN articles in all four journals showed a steady rise but with a 12 yr lag behind the US. We conclude that the astronomical research rates in all three regions have not yet reached a maximum.

The Taiwanese-American Occultation Survey (TAOS) monitors fields of up to ∼1000 stars at 5 Hz simultaneously with four small telescopes to detect occultation events from small (∼1 km) Kuiper Belt Objects (KBOs). The survey presents a number of challenges, in particular the fact that the occultation events we are searching for are extremely rare and are typically manifested as slight flux drops for only one or two consecutive time series measurements. We have developed a statistical analysis technique to search the multi-telescope data set for simultaneous flux drops which provides a robust false-positive rejection and calculation of event significance. In this article, we describe in detail this statistical technique and its application to the TAOS data set.

CfunBASE is a customizable C# cosmological functions library in the .NET framework. Its primary use is in CasJobs/SkyServer, where the functions are ported into a MS-SQL Server database hosting the SDSS science archive, and can be executed through simple T-SQL commands. This gives cloud-computing users the possibility of calculating cosmological distances, volumes and times as a function of redshift, as well as their respective inverse functions. Also included are basic data exploratory analysis tools, such as binning, N-dimensional weighted histograms, and quantile and cumulative distribution aggregate functions. Advanced astronomical examples are presented and discussed, such as the T-SQL implementation and fast computation of luminosity functions, color-magnitude diagrams, and the friends-of-friends galaxy cluster identification algorithm.