The Astrophysical Journal Supplement publishes significant papers containing extensive data or calculations, or of very specialized interest. The Supplement contains many of the most frequently cited papers in the astronomical literature.
Number 1, 2015 January (1-3)
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These are the latest articles published in The Astrophysical Journal Supplement Series.
M. Andersson et al. 2015 ApJS 216 2
The three Mn I lines at 17325, 17339, and 17349 Å are among the 25 strongest lines (log ( gf) > 0.5) in the H band. They are all heavily broadened due to hyperfine structure, and the profiles of these lines have so far not been understood. Earlier studies of these lines even suggested that they were blended. In this work, the profiles of these three infrared (IR) lines have been studied theoretically and compared to experimental spectra to assist in the complete understanding of the solar spectrum in the IR. It is shown that the structure of these lines cannot be described in the conventional way using the diagonal A and B hyperfine interaction constants. The off-diagonal hyperfine interaction not only has a large impact on the energies of the hyperfine levels, but also introduces a large intensity redistribution among the hyperfine lines, changing the line profiles dramatically. By performing large-scale calculations of the diagonal and off-diagonal hyperfine interaction and the gf-values between the upper and lower hyperfine levels and using a semi-empirical fitting procedure, we achieved agreement between our synthetic and experimental spectra. Furthermore, we compare our results with observations of stellar spectra. The spectra of the Sun and the K1.5 III red giant star Arcturus were modeled in the relevant region, 1.73-1.74 μm, using our theoretically predicted gf-values and energies for each individual hyperfine line. Satisfactory fits were obtained and clear improvements were found using our new data compared with the old available Mn I data. A complete list of energies and gf-values for all the 3 d 54 s( 7 S)4 d e 6D - 3 d 54 s( 7 S)4 f w 6F hyperfine lines are available as supporting material, whereas only the stronger lines are presented and discussed in detail in this paper.
G. Tejeda et al. 2015 ApJS 216 3
State-to-state rate coefficients for ortho-H 2O:He and para-H 2O:He inelastic collisions in the 20-120 K thermal range are investigated by means of an improved experimental procedure. This procedure is based on the use of a kinetic master equation (MEQ) which describes the evolution of populations of H 2O rotational levels along a supersonic jet of H 2O highly diluted in helium. The MEQ is expressed in terms of experimental observables and rate coefficients for H 2O:He inelastic collisions. The primary experimental observables are the local number density and the populations of the rotational energy levels of H 2O, quantities which are determined along the jet with unprecedented accuracy by means of Raman spectroscopy with high space resolution. Sets of rate coefficients from the literature and from present close-coupling calculations using two different potential energy surfaces (PESs) have been tested against the experiment. The Green et al. rate coefficients are up to 50% too low compared to the experiment, while most rates calculated here from the Hodges et al. PES and the Patkowski et al. PES are much closer to the experimental values. Experimental rates with an estimated accuracy on the order of 10% have been obtained for ortho-H 2O:He and para-H 2O:He inelastic collisions between 20 and 120 K by scaling and averaging the theoretical rates to the experiment.
Ruth C. Peterson and Robert L. Kurucz 2015 ApJS 216 1
The spectrum of the Fe I atom is critical to many areas of astrophysics and beyond. Measurements of the energies of its high-lying levels remain woefully incomplete, however, despite extensive laboratory and solar analysis. In this work, we use high-resolution archival absorption-line ultraviolet and optical spectra of stars whose warm temperatures favor moderate Fe I excitation. We derive the energy for a particular upper level in Kurucz's semiempirical calculations by adopting a trial value that yields the same wavelength for a given line predicted to be about as strong as that of a strong unidentified spectral line observed in the stellar spectra, then checking the new wavelengths of other strong predicted transitions that share the same upper level for coincidence with other strong observed unidentified lines. To date, this analysis has provided the upper energies of 66 Fe I levels. Many new energy levels are higher than those accessible to laboratory experiments; several exceed the Fe I ionization energy. These levels provide new identifications for over 2000 potentially detectable lines. Almost all of the new levels of odd parity include UV lines that were detected but unclassified in laboratory Fe I absorption spectra, providing an external check on the energy values. We motivate and present the procedure, provide the resulting new energy levels and their uncertainties, list all the potentially detectable UV and optical new Fe I line identifications and their gf values, point out new lines of astrophysical interest, and discuss the prospects for additional Fe I energy level determinations.
G. Yang et al. 2014 ApJS 215 27
We derive photometric redshifts ( z phot) for sources in the entire (~0.4 deg 2) Hawaii-Hubble Deep Field-North (H-HDF-N) field with the EAzY code, based on point-spread-function-matched photometry of 15 broad bands from the ultraviolet ( U band) to mid-infrared (IRAC 4.5 μm). Our catalog consists of a total of 131,678 sources. We evaluate the z phot quality by comparing z phot with spectroscopic redshifts ( z spec) when available, and find a value of normalized median absolute deviation σ NMAD = 0.029 and an outlier fraction of 5.5% (outliers are defined as sources having |z phot – z spec |/(1 + z spec ) > 0.15) for non-X-ray sources. More specifically, we obtain σ NMAD = 0.024 with 2.7% outliers for sources brighter than R = 23 mag, σ NMAD = 0.035 with 7.4% outliers for sources fainter than R = 23 mag, σ NMAD = 0.026 with 3.9% outliers for sources having z < 1, and σ NMAD = 0.034 with 9.0% outliers for sources having z > 1. Our z phot quality shows an overall improvement over an earlier z phot work that focused only on the central H-HDF-N area. We also classify each object as a star or galaxy through template spectral energy distribution fitting and complementary morphological parameterization, resulting in 4959 stars and 126,719 galaxies. Furthermore, we match our catalog with the 2 Ms Chandra Deep Field-North main X-ray catalog. For the 462 matched non-stellar X-ray sources (281 having z spec), we improve their z phot quality by adding three additional active galactic nucleus templates, achieving σ NMAD = 0.035 and an outlier fraction of 12.5%. We make our catalog publicly available presenting both photometry and z phot, and provide guidance on how to make use of our catalog.
Ethan Vishniac and Frederic Rasio 2014 ApJS 215 16