- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1704
- Title:
- ExoMol line lists for formaldehyde H_2_CO
- Short Name:
- J/MNRAS/448/1704
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A computed line list for formaldehyde, H_2_^12^C^16^O, applicable to temperatures up to T=1500K is presented. An empirical potential energy and ab initio dipole moment surfaces are used as the input to nuclear motion program TROVE. The resulting line list, referred to as AYTY, contains 10.3 million rotational-vibrational states and around 10 billion transition frequencies. Each transition includes associated Einstein- A coefficients and absolute transition intensities, for wavenumbers below 10000cm^-1^ and rotational excitations up to J=70. Room-temperature spectra are compared with laboratory measurements and data currently available in the HITRAN database. These spectra show excellent agreement with experimental spectra and highlight the gaps and limitations of the HITRAN data. The full line list is available from the CDS database as well as at www.exomol.com.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/2337
- Title:
- ExoMol line lists for phosphine (PH_3_)
- Short Name:
- J/MNRAS/446/2337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive hot line list is calculated for ^31^PH_3_ in its ground electronic state. This line list, called SAlTY, contains almost 16.8 billion transitions between 7.5 million energy levels and it is suitable for simulating spectra up to temperatures of 1500K. It covers wavelengths longer than 1um and includes all transitions to upper states with energies below hc.18000cm^-1^ and rotational excitation up to J=46. The line list is computed by variational solution of the Schrodinger equation for the rotation-vibration motion employing the nuclear-motion program TROVE. A previously reported ab initio dipole moment surface is used as well as an updated 'spectroscopic' potential energy surface (PES), obtained by refining an existing ab initio surface through least-squares fitting to the experimentally derived energies. Detailed comparisons with other available sources of phosphine transitions confirms SAlTY's accuracy and illustrates the incompleteness of previous experimental and theoretical compilations for temperatures above 300K. Atmospheric models are expected to severely underestimate the abundance of phosphine in disequilibrium environments, and it is predicted that phosphine will be detectable in the upper troposphere of many substellar objects. This list is suitable for modelling atmospheres of many astrophysical environments, namely carbon stars, Y dwarfs, T dwarfs, hot Jupiters and solar system gas giant planets. It is available in full as supplementary data to the article and at www.exomol.com.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/1469
- Title:
- ExoMol line lists for SiO
- Short Name:
- J/MNRAS/434/1469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate rotation-vibration line lists are calculated for silicon monoxide. Line lists are presented for the main isotopologue, ^28^Si^16^O, and four monosubstituted isotopologues ^29^Si^16^O, ^30^Si^16^O, ^28^Si^17^O and ^28^Si^18^O, in their ground electronic states. These line lists are suitable for high temperatures (up to 9000K) including those relevant to exoplanetary atmospheres and cool stars. A combination of empirical and ab initio methods is used: the potential energy curves are determined to high accuracy by fitting to extensive data from analysis of both laboratory and sunspot spectra; a high quality ab initio dipole moment curve is calculated at the large basis set, multi-reference configuration interaction (MRCI) level. A partition function plus full line lists of rotation-vibration transitions are made available in an electronic form as supplementary data to this article and at www.exomol.com.
- ID:
- ivo://CDS.VizieR/J/A+A/430/911
- Title:
- Expansive components in HII regions
- Short Name:
- J/A+A/430/911
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the presence of low intensity high velocity components, which we have termed wing features in the integrated Halpha emission line profiles of the HII region populations of the spiral barred galaxies NGC 1530, NGC 3359 and NGC 6951. We find that more than a third of the HII region line profiles in each galaxy show these components.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/56
- Title:
- Experimental spectrum of methanol (CH_3_OH)
- Short Name:
- J/ApJ/795/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectrum of methanol (CH_3_OH) has been characterized between 214.6 and 265.4 GHz for astrophysically significant temperatures. Four hundred and eighty-six spectra with absolute intensity calibration recorded between 240 and 389 K provided a means for the calculation of the complete experimental spectrum (CES) of methanol as a function of temperature. The CES includes contributions from v_t_=3 and other higher states that are difficult to model quantum mechanically (QM). It also includes the spectrum of the ^13^C isotopologue in terrestrial abundance. In general the QM models provide frequencies that are within 1 MHz of their experimental values, but there are several outliers that differ by tens of MHz. As in our recent work on methanol in the 560-654 GHz region, significant intensity differences between our experimental intensities and cataloged values were found. In this work these differences are explored in the context of several QM analyses. The experimental results presented here are analyzed to provide a frequency point-by-point catalog that is well suited for the simulation of crowded and overlapped spectra. Additionally, a catalog in the usual line frequency, line strength, and lower state energy format is provided.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/11
- Title:
- Exploring 6 AGN dusty torus models. II.
- Short Name:
- J/ApJ/884/11
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers devoted to exploring a set of six dusty models of active galactic nuclei (AGN) with available spectral energy distributions. These models are the smooth torus by Fritz+ (2006MNRAS.366..767F), the clumpy torus by Nenkova+ (2008ApJ...685..147N and 2008ApJ...685..160N), the clumpy torus by Honig & Kishimoto (2010A&A...523A..27H), the two-phase torus by Siebenmorgen+ (2015A&A...583A.120S), the two-phase torus by Stalevski+ (2012MNRAS.420.2756S and 2016MNRAS.458.2288S), and the wind model by Honig & Kishimoto (2017ApJ...838L..20H). The first paper explores discrimination among models and the parameter restriction using synthetic spectra. Here we perform spectral fitting of a sample of 110 AGN drawn from the Swift/BAT survey with Spitzer/IRS spectroscopic data. The aim is to explore which is the model that describes better the data and the resulting parameters. The clumpy wind-disk model by Honig & Kishimoto provides good fits for ~50% of the sample, and the clumpy torus model by Nenkova+ is good at describing ~30% of the objects. The wind-disk model by Honig & Kishimoto is better for reproducing the mid-infrared spectra of type 1 Seyferts (with 60% of the type 1 Seyferts well reproduced by this model compared to the 10% well represented by the clumpy torus model by Nenkova+), while type 2 Seyferts are equally fitted by both models (roughly 40% of the type 2 Seyferts). Large residuals are found irrespective of the model used, indicating that the AGN dust continuum emission is more complex than predicted by the models or that the parameter space is not well sampled. We found that all the resulting parameters for our AGN sample are roughly constrained to 10%-20% of the parameter space. Contrary to what is generally assumed, the derived outer radius of the torus is smaller (reaching up to a factor of ~5 smaller for 10pc tori) for the smooth torus by Fritz+ and the two-phase torus by Stalevski+ than the one derived from the clumpy torus by Nenkova+ Covering factors and line-of-sight viewing angles strongly depend on the model used. The total dust mass is the most robust derived quantity, giving equivalent results for four of these models.
- ID:
- ivo://CDS.VizieR/J/ApJS/228/19
- Title:
- Exploring the SDSS data set. I. EMP & CV stars
- Short Name:
- J/ApJS/228/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for extremely metal-poor (EMP), carbon-enhanced metal-poor (CEMP), and cataclysmic variable (CV) stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets, and it can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct our search using the SDSS DR10 data set. We first created a 3326-dimensional phase space containing nearly 2 billion measures of the strengths of over 1600 spectral features in 569738 SDSS stars. These measures capture essentially all the stellar atomic and molecular species visible at the resolution of SDSS spectra. We show how LSPs can be used to quickly isolate and examine interesting portions of this phase space. To illustrate, we use LSPs coupled with cuts in selected portions of phase space to extract EMP stars, CEMP stars, and CV stars. We present identifications for 59 previously unrecognized candidate EMP stars and 11 previously unrecognized candidate CEMP stars. We also call attention to 2 candidate He II emission CV stars found by the LSP approach that have not yet been discussed in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/32
- Title:
- Extended abundance analysis of cool stars
- Short Name:
- J/ApJS/225/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of uniformly determined stellar properties and abundances for 1615 F, G, and K stars using an automated spectral synthesis modeling procedure. All stars were observed using the HIRES spectrograph at Keck Observatory. Our procedure used a single line list to fit model spectra to observations of all stars to determine effective temperature, surface gravity, metallicity, projected rotational velocity, and the abundances of 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Sixty percent of the sample had Hipparcos parallaxes and V-band photometry, which we combined with the spectroscopic results to obtain mass, radius, and luminosity. Additionally, we used the luminosity, effective temperature, metallicity and {alpha}-element enhancement to interpolate in the Yonsei-Yale isochrones to derive mass, radius, gravity, and age ranges for those stars. Finally, we determined new relations between effective temperature and macroturbulence for dwarfs and subgiants. Our analysis achieved precisions of 25K in T_eff_, 0.01dex in [M/H], 0.028dex for logg, and 0.5km/s in vsini based on multiple observations of the same stars. The abundance results were similarly precise, between ~0.01 and ~0.04dex, though trends with respect to T_eff_ remained for which we derived empirical corrections. The trends, though small, were much larger than our uncertainties and are shared with published abundances. We show that changing our model atmosphere grid accounts for most of the trend in [M/H] between 5000 and 5500K, indicating a possible problem with the atmosphere models or opacities.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/38
- Title:
- Extended abundance analysis of KOIs
- Short Name:
- J/ApJS/237/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate stellar parameters and precise elemental abundances are vital pieces to correctly characterize discovered planetary systems, better understand planet formation, and trace galactic chemical evolution. We have performed a uniform spectroscopic analysis for 1127 stars, yielding accurate gravity, temperature, and projected rotational velocity in addition to precise abundances for 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Most of the stars in this sample are Kepler Objects of Interest, observed by the California-Kepler Survey, and include 1003 stars hosting 1562 confirmed planets. This catalog extends the uniform analysis of our previous catalog, bringing the total number of homogeneously analyzed stars to almost 2700 F, G, and K dwarfs. To ensure consistency between the catalogs, we performed an analysis of our ability to recover parameters as a function of signal-to-noise ratio (S/N) and present individual uncertainties as well as functions to calculate uncertainties for parameters derived from lower S/N spectra. With the updated parameters, we used isochrone fitting to derive new radii, masses, and ages for the stars. We use our abundance analysis to support the finding that the radius gap is likely a result of evolution rather than the result of primordial compositional differences between the two populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/3263
- Title:
- Extended galaxy halo gas through HI and OVI
- Short Name:
- J/MNRAS/449/3263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of extended galaxy halo gas through HI and OVI absorption over two decades in projected distance at z~0.2. The study is based on a sample of 95 galaxies from a highly complete (>80 percent) survey of faint galaxies (L>0.1L*) with archival quasar absorption spectra and 53 galaxies from the literature. A clear anticorrelation is found between HI (OVI) column density and virial radius normalized projected distance, d/Rh. Strong HI (OVI) absorption systems with column densities greater than 10^14.0^ (10^13.5^)cm^-2^ are found for 48 of 54 (36 of 42) galaxies at d<Rh indicating a mean covering fraction of <{kappa}_HI_>=0.89 (<{kappa}_OVI_>=0.86). OVI absorbers are found at d~Rh, beyond the extent observed for lower ionization species. At d/Rh=1-3 strong HI (OVI) absorption systems are found for only 7 of 43 (5 of 34) galaxies (<{kappa}_HI_>=0.16 and <{kappa}_OVI_>=0.15). Beyond d=3Rh, the HI and OVI covering fractions decrease to levels consistent with coincidental systems. The high completeness of the galaxy survey enables an investigation of environmental dependence of extended gas properties. Galaxies with nearby neighbours exhibit a modest increase in Ovi covering fraction at d>Rh compared to isolated galaxies (<{kappa}_OVI_~0.13 versus 0.04) but no excess HI absorption. These findings suggest that environmental effects play a role in distributing heavy elements beyond the enriched gaseous haloes of individual galaxies. Finally, we find that differential HI and OVI absorption between early- and late-type galaxies continues from d<Rh to d~3Rh.
