- ID:
- ivo://CDS.VizieR/J/ApJS/66/387
- Title:
- Case low-dispersion Survey VII.
- Short Name:
- J/ApJS/66/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observational data on 132 faint (R magnitude = 9-17) red stars with carbon-star or late M-type spectra are presented in tables and briefly characterized. The data were collected in a survey of a 1000-sq deg region at high northern Galactic latitude (right ascension 8h15 to 17h30 and declination +29 to +38 deg) on low-dispersion 330-535-nm objective-prism plates obtained with the 61/91-cm Burrell Schmidt telescope at Kitt Peak Observatory.
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- ID:
- ivo://CDS.VizieR/J/A+A/539/A51
- Title:
- Catalogue enriched with R CrB stars
- Short Name:
- J/A+A/539/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains 1602 entries. It was created to list objects that have similar near- and mid-infrared characteristics than R Coronae Borealis (RCB) stars which are supergiant and hydrogen-deficient stars known to possess a hot circumstellar shell. It is therefore a catalogue enriched with RCB stars and further spectroscopic follow-ups are needed to reveal the nature of each object. The catalogue was produced from a series of selection criteria on the infrared colour of sources published in the Preliminary WISE data release (2011). These sources spread over 57% of the entire sky. They have also all been detected in each J, H and K bands of the 2MASS catalogue.
- ID:
- ivo://CDS.VizieR/V/18
- Title:
- Catalogue of Late-type Stars with Maser Emission
- Short Name:
- V/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of more than 300 late type stars which display maser line radio emission in OH, H2O or SiO molecules has been compiled. About two thirds of the objects have been identified with optical or infrared optics, mostly M-supergiants, Mira, or semiregular variables. The catalog contains optical data such as spectral type, period and magnitude, radio flux densities and velocities and infrared flux densities in the region between 0.7 and 20 micrometers.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A89
- Title:
- Center-to-limb polarization of FGK stars
- Short Name:
- J/A+A/575/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Scattering and absorption processes in stellar atmosphere act the center-to-limb variations of the intensity (CLVI) and the linear polarization (CLVP) of stellar radiation. There are several theoretical and observational studies of CLVI using different stellar models, however, most studies of CLVP have concentrated on the solar atmosphere and have not considered the CLVP in cooler non-gray stellar atmospheres at all. In this paper, we present a theoretical study of the CLV of the intensity and the linear polarization in continuum spectra of different spectral type stars. We solve the radiative transfer equations for polarized light iteratively assuming no magnetic field and considering a planeparallel model atmospheres and various opacities.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A87
- Title:
- Center-to-limb polarization of FGK stars
- Short Name:
- J/A+A/586/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the necessary parameters needed for the interpretation of the light curves of transiting exoplanets or eclipsing binary stars (as well as interferometric measurements of a star or microlensing events) is how the intensity and polarization of light changes from the center to the limb of a star. Scattering and absorption processes in the stellar atmosphere affect both the center-to-limb variation of intensity (CLVI) and polarization (CLVP). In this paper, we present a study of the CLVI and CLVP in continuum spectra, taking into consideration the different contributions of scattering and absorption opacity for a variety of spectral type stars with spherical atmospheres. We solve the radiative transfer equation for polarized light in the presence of a continuum scattering, taking into consideration the spherical model of a stellar atmosphere. To cross-check our results, we developed two independent codes that are based on Feautrier and short characteristics methods, respectively, We calculate the center-to-limb variation of intensity (CLVI) and polarization (CLVP) in continuum for the Phoenix grid of spherical stellar model atmospheres for a range of effective temperatures (4000-7000K), gravities (logg=1.0-5.5), and wavelengths (4000-7000{AA}). In addition, we present several tests of our codes and compare our calculations for the solar atmosphere with published photometric and polarimetric measurements. We also show that our two codes provide similar results in all considered cases.
- ID:
- ivo://CDS.VizieR/J/ApJ/683/424
- Title:
- CHARA observations of 3 late-type stars
- Short Name:
- J/ApJ/683/424
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the longest baselines of the CHARA Array, we have measured the angular diameter of the G5V subdwarf {mu} Cas A, the first such determination for a halo population star. We compare this result to new diameters for the higher metallicity K0V stars, {sigma} Dra and HR 511, and find that the metal-poor star, {mu} Cas A, has an effective temperature (T_eff_=5297+/-32K), radius (R=0.791+/-0.008R_{sun}_), and absolute luminosity (L=0.442+/-0.014L_{sun}_) comparable to those of the other two stars with later spectral types. We show that stellar models show a discrepancy in the predicted temperature and radius for {mu} Cas A, and we discuss these results and how they provide a key to understanding the fundamental relationships for stars with low metallicity.
- ID:
- ivo://CDS.VizieR/III/193
- Title:
- Chemical Abundances in Late-Type Stars
- Short Name:
- III/193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue includes chemical abundances determinations (from Li to Eu) and atmospheric parameters (Teff, logg, microturbulent velocity) obtained from re-analyses of 1108 Late-Type Stars. It contains field stars of the Galaxy, of open and globular cluster stars, and stars belonging to the LMC and the SMC. Almost all of these stars are referenced in the Cayrel de Strobel et al.'s [Fe/H] catalog (see cat. <III/200>). Most of the abundance results are very reliable within 0.2dex when using different sources of equivalent widths taken from the literature for a given star.
- ID:
- ivo://CDS.VizieR/J/A+A/360/509
- Title:
- Chemical abundances in 7 red giants
- Short Name:
- J/A+A/360/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances of about fifteen elements from oxygen to europium are measured in seven red giants of the two open clusters NGC 2360 and NGC 2447. The effective temperatures of the giants are determined spectroscopically by taking advantage of their known masses (~2M_{sun}_ in NGC 2360 and ~3M_{sun}_ in NGC 2447) and bolometric magnitudes. The average iron abundances we obtain for the two clusters are [Fe/H]=0.07 for NGC 2360 and [Fe/H]=0.03 for NGC 2447.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A50
- Title:
- Chemical abundances of giants and subgiants
- Short Name:
- J/A+A/574/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present fundamental stellar parameters, chemical abundances, and rotational velocities for a sample of 86 evolved stars with planets (56 giants; 30 subgiants), and for a control sample of 137 stars (101 giants; 36 subgiants) without planets. The analysis was based on both high signal-to-noise and resolution echelle spectra. The main goals of this work are i) to investigate chemical differences between evolved stars that host planets and those of the control sample without planets; ii) to explore potential differences between the properties of the planets around giants and subgiants; and iii) to search for possible correlations between these properties and the chemical abundances of their host stars. Implications for the scenarios of planet formation and evolution are also discussed. The fundamental stellar parameters (T_eff_, logg, [Fe/H], {xi}_t_) were computed homogeneously using the FUNDPAR code. The chemical abundances of 14 elements (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Zn, and Ba) were obtained using the MOOG code. Rotational velocities were derived from the full width at half maximum of iron isolated lines. In agreement with previous studies, we find that subgiants with planets are, on average, more metal-rich than subgiants without planets by ~0.16dex. The [Fe/H] distribution of giants with planets is centered at slightly subsolar metallicities and there is no metallicity enhancement relative to the [Fe/H] distribution of giants without planets. Furthermore, contrary to recent results, we do not find any clear difference between the metallicity distributions of stars with and without planets for giants with M_*_>1.5M_{sun}_. With regard to the other chemical elements, the analysis of the [X/Fe] distributions shows differences between giants with and without planets for some elements, particularly V, Co, and Ba. Subgiants with and without planets exhibit similar behavior for most of the elements. On the other hand, we find no evidence of rapid rotation among the giants with planets or among the giants without planets. Finally, analyzing the planet properties, some interesting trends might be emerging: i) multi-planet systems around evolved stars show a slight metallicity enhancement compared with single-planet systems; ii) planets with a<~0.5AU orbit subgiants with [Fe/H]>0 and giants hosting planets with a<~1AU have [Fe/H]<0; iii) higher-mass planets tend to orbit more metal-poor giants with M_*_<=1.5M_{sun}_, whereas planets around subgiants seem to follow the planet-mass metallicity trend observed on dwarf hosts; iv) [X/Fe] ratios for Na, Si, and Al seem to increase with the mass of planets around giants; v) planets orbiting giants show lower orbital eccentricities than those orbiting subgiants and dwarfs, suggesting a more efficient tidal circularization or the result of the engulfment of close-in planets with larger eccentricities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/1095
- Title:
- Chemical analysis of CH stars
- Short Name:
- J/MNRAS/440/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results from high-resolution spectral analyses of a selected sample of CH stars are presented. Detailed chemical composition studies of these objects, which could reveal abundance patterns that in turn provide information regarding nucleosynthesis and evolutionary status, are scarce in the literature. We conducted detailed chemical composition studies for these objects based on high-resolution (R~42000) spectra. The spectra were taken from the ELODIE archive and cover the wavelength range from 3900 to 6800{AA}. We estimated the stellar atmospheric parameters, the effective temperature T_eff_, the surface gravity logg, and the metallicity [Fe/H] from local thermodynamic equilibrium analyses using model atmospheres. Estimated temperatures of these objects cover a wide range, from 4550 to 6030K. The surface gravity ranges from 1.8 to 3.8, and the metallicity from -0.18 to -1.4. We report updates on elemental abundances for several heavy elements and present estimates of abundance ratios for Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu and Dy with respect to Fe. For the object HD 188650 we present the first abundance analysis results based on a high-resolution spectrum. Enhancements of heavy elements relative to Fe, which are characteristic of CH stars, are evident from our analyses for most of the objects. A parametric model-based study was performed to understand the relative contributions from the s- and r-processes to the abundances of the heavy elements.
