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31. Galactic Cepheid abundances
ID:
ivo://CDS.VizieR/J/A+A/381/32
Title:
Galactic Cepheid abundances
Short Name:
J/A+A/381/32
Date:
21 Oct 2021
Publisher:
CDS
Description:
File table1 contains information about the program stars and spectra . Note that we also added to our sample two distant Cepheids (TV Cam and YZ Aur) which were previously analyzed by Harris & Pilachowski (1984ApJ...282..655H). File table2 contains relative-to-solar averaged elemental abundances (i.e. [El/H]) for program stars. First column gives the name of the star, other columns list the abundance data for all investigated elements. File tablea1 contains an Appendix table with elemental abundances from individual ions (ions are listed in the first column). For each star the following information is given: relative-to-solar abundance of a given ion (i.e. [M/H]), sigma-value, number of the lines used in analysis, absolute abundance of a given ion (M/H) in the scale where logA(H)=12.00.
32. 22-GHz water maser clouds
ID:
ivo://CDS.VizieR/J/A+A/546/A16
Title:
22-GHz water maser clouds
Short Name:
J/A+A/546/A16
Date:
21 Oct 2021
Publisher:
CDS
Description:
Cool, evolved stars undergo copious mass loss but the detailed mechanisms and the form in which the matter is returned the ISM are still under debate. We investigated the structure and evolution of the wind at 5 to 50 stellar radii from Asymptotic Giant Branch and Red Supergiant stars.
33. HR study of massive supergiants in Per OB1
ID:
ivo://CDS.VizieR/J/A+A/643/A116
Title:
HR study of massive supergiants in Per OB1
Short Name:
J/A+A/643/A116
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Perseus OB1 association, including the h and chi Persei double cluster, is an interesting laboratory for the investigation of massive star evolution as it hosts one of the most populous groupings of blue and red supergiants (Sgs) in the Galaxy at a moderate distance and extinction. We discuss whether the massive O-type, and blue and red Sg stars located in the Per OB1 region are members of the same population, and examine their binary and runaway status. We gathered a total of 405 high-resolution spectra for 88 suitable candidates around 4.5 deg from the center of the association, and compiled astrometric information from Gaia DR2 for all of them. This was used to investigate membership and identify runaway stars. By obtaining high-precision radial velocity (RV) estimates for all available spectra, we investigated the RV distribution of the global sample (as well as different subsamples) and identified spectroscopic binaries (SBs). Most of the investigated stars belong to a physically linked population located at d=2.5+/-0.4kpc. We identify 79 confirmed or likely members, and 5 member candidates. No important differences are detected in the distribution of parallaxes when stars in h and chi Persei or the full sample are considered. In contrast, most O-type stars seem to be part of a differentiated population in terms of kinematical properties. In particular, the percentage of runaways among them (45%) is considerable higher than for the more evolved targets (which is lower than ~5% in all cases). A similar tendency is also found for the percentage of clearly detected SBs, which already decreases from 15% to 10% when the O star and B Sg samples are compared, respectively, and practically vanishes in the cooler Sgs. Concerning this latter result, our study illustrates the importance of taking the effect of the ubiquitous presence of intrinsic variability in the blue-to-red Sg domain into account to avoid the spurious identification of pulsating stars as SBs. All but 4 stars in our working sample (including 10 O giants/Sgs, 36 B Sgs, 9 B giants, 11 A/F Sgs, and 18 red Sgs) can be considered as part of the same (interrelated) population. However, any further attempt to describe the empirical properties of this sample of massive stars in an evolutionary context must take into account that an important fraction of the O stars is or likely has been part of a binary/multiple system. In addition, some of the other more evolved targets may have also been affected by binary evolution. In this line of argument, it is also interesting to note that the percentage of spectroscopic binaries within the evolved population of massive stars in Per OB1 is lower by a factor 4-5 than in the case of dedicated surveys of O-type stars in other environments that include a much younger population of massive stars.
34. IK Tau and HIP 20188 visible polarimetric imaging
ID:
ivo://CDS.VizieR/J/A+A/628/A132
Title:
IK Tau and HIP 20188 visible polarimetric imaging
Short Name:
J/A+A/628/A132
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present visible polarimetric imaging observations of the oxygen-rich AGB star IK Tau obtained with SPHERE-ZIMPOL (phase 0.27) as well as interferometric observations with AMBER. The polarimetric imaging capabilities of SPHERE-ZIMPOL have allowed us to spatially resolve clumpy dust clouds at 20-50mas from the central star, which corresponds to 2-5R* when combined with a central star's angular diameter of 20.7+/-1.53 mas measured with AMBER. The diffuse, asymmetric dust emission extends out to ~73R*. We find that the TiO emission extends to 150 mas (15R*). The AMBER data in the CO lines also suggest a molecular outer atmosphere extending to ~1.5R*. The results of our 2-D Monte Carlo radiative transfer modelling of dust clumps suggest that the polarized intensity and degree of linear polarization can be reasonably explained by small-sized (0.1{mu}m) grains of Al_2_O_3, MgSiO_3, or Mg_2_SiO_4 in an optically thin shell ({tau}_550 nm=0.5+/-0.1) with an inner boundary radius of 3.5*. IK Tau's mass-loss rate is 20 to 50 times higher than the previously studied AGB stars W Hya, R Dor, and o Cet. Nevertheless, our observations of IK Tau revealed that clumpy dust formation occurs close to the star as seen in those low mass-rate AGB stars.
35. IR photometry of LMC O-rich evolved stars
ID:
ivo://CDS.VizieR/J/MNRAS/440/631
Title:
IR photometry of LMC O-rich evolved stars
Short Name:
J/MNRAS/440/631
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich asymptotic giant branch (AGB) stars, we have computed a grid of MODUST radiative-transfer models for a range of dust compositions, mass-loss rates, dust-shell inner radii and stellar parameters. We compare the resulting colours with the observed oxygen-rich AGB stars from the SAGE-Spec Large Magellanic Cloud (LMC) sample, finding good overall agreement for stars with a mid-infrared excess. We use these models to fit a sample of 37 O-rich AGB stars in the LMC with optically thin circumstellar envelopes, for which 5-35{mu}m Spitzer infrared spectrograph (IRS) spectra and broad-band photometry from the optical to the mid-infrared are available. From the modelling, we find mass-loss rates in the range ~8x10^-8^-5x10^-6^M_{sun}_/yr, and we show that a grain mixture consisting primarily of amorphous silicates, with contributions from amorphous alumina and metallic iron, provides a good fit to the observed spectra. Furthermore, we show from dust models that the AKARI [11]-[15] versus [3.2]-[7] colour-colour diagram is able to determine the fractional abundance of alumina in O-rich AGB stars.
36. IR spectra of oxygen-rich evolved stars
ID:
ivo://CDS.VizieR/J/A+AS/146/437
Title:
IR spectra of oxygen-rich evolved stars
Short Name:
J/A+AS/146/437
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed the 8-13.5{mu}m UKIRT CGS3 spectra of 142 M-type stars including 80 oxygen-rich AGB stars and 62 red supergiants, with a view to understanding the differences and similarities between the dust features of these stars. We have classified the spectra into groups according to the observed appearance of the infrared features.
37. IRTF spectral indices for giant stars
ID:
ivo://CDS.VizieR/J/AJ/162/187
Title:
IRTF spectral indices for giant stars
Short Name:
J/AJ/162/187
Date:
15 Mar 2022
Publisher:
CDS
Description:
We present infrared spectral indices (1.0-2.3{mu}m) of Galactic late-type giants and red supergiants (RSGs). We used existing and new spectra obtained at resolution power R=2000 with SpeX on the IRTF telescope. While a large CO equivalent width (EW), at 2.29{mu}m ([CO,2.29]>~45{AA}) is a typical signature of RSGs later than spectral type M0, [CO] of K-type RSGs and giants are similar. In the [CO,2.29] versus [MgI,1.71] diagram, RSGs of all spectral types can be distinguished from red giants because the MgI line weakens with increasing temperature and decreasing gravity. We find several lines that vary with luminosity, but not temperature: SiI (1.59{mu}m), Sr (1.033{mu}m), Fe+Cr+Si+CN (1.16{mu}m), Fe+Ti (1.185{mu}m), Fe+Ti (1.196{mu}m), Ti+Ca (1.28{mu}m), and Mn (1.29{mu}m). Good markers of CN enhancement are the Fe+Si+CN line at 1.087{mu}m and CN line at 1.093{mu}m. Using these lines, at the resolution of SpeX, it is possible to separate RSGs and giants. Contaminant O-rich Mira and S-type AGBs are recognized by strong molecular features due to water vapor features, TiO band heads, and/or ZrO absorption. Among the 42 candidate RSGs that we observed, all but one were found to be late types. Twenty-one have EWs consistent with those of RSGs, 16 with those of O-rich Mira AGBs, and one with an S-type AGB. These infrared results open new, unexplored, potential for searches at low resolution of RSGs in the highly obscured innermost regions of the Milky Way.
38. IUE sample of binaries with hot component
ID:
ivo://CDS.VizieR/J/ApJS/119/83
Title:
IUE sample of binaries with hot component
Short Name:
J/ApJS/119/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained or retrieved IUE spectra for over 100 middle- and late-type giant and supergiant stars whose spectra indicate the presence of a hot component earlier than type F2. The hot companions are classified accurately by temperature class from their far-UV spectra. The interstellar extinction of each system and the relative luminosities of the components are derived from analysis of the UV and optical fluxes, using a grid of UV intrinsic colors for hot dwarfs. We find that there is fair agreement in general between current UV spectral classification and ground-based hot component types, in spite of the difficulties of assigning the latter. There are a few cases in which the cool component optical classifications disagree considerably with the temperature classes inferred from our analysis of UV and optical photometry. The extinction parameter agrees moderately well with other determinations of B-V color excess. Many systems are worthy of further study especially to establish their spectroscopic orbits. Further work is planned to estimate luminosities of the cool components from the data herein; in many cases, these luminosities' accuracies should be comparable to or exceed those of the Hipparcos parallaxes.
39. K-band spectrum of the very massive star W49nr1
ID:
ivo://CDS.VizieR/J/A+A/568/L13
Title:
K-band spectrum of the very massive star W49nr1
Short Name:
J/A+A/568/L13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Very massive stars (M>100M_{sun}_) are very rare objects, but have a strong influence on their environment. The formation of this kind of objects is of prime importance in star formation, but observationally still poorly constrained. We report on the identification of a very massive star in the central cluster of the star-forming region W49. We investigate near-infrared K-band spectroscopic observations of W49 from VLT/ISAAC together with JHK images obtained with NTT/SOFI and LBT/LUCI. We derive a spectral type of W49nr1, the brightest star in the dense core of the central cluster of W49.
40. K-M stars of class I candidate RSGs in Gaia DR2
ID:
ivo://CDS.VizieR/J/AJ/158/20
Title:
K-M stars of class I candidate RSGs in Gaia DR2
Short Name:
J/AJ/158/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate individual distances and luminosities of a sample of 889 nearby candidate red supergiants (RSGs) with reliable parallaxes ({omega}/{sigma}_{omega}_>4 and RUWE<2.7) from Gaia Data Release 2 (DR2, Cat. I/345). The sample was extracted from the historical compilation of spectroscopically derived spectral types by Skiff (Cat. B/mk), and consists of K-M stars that are listed with class I at least once. The sample includes well-known RSGs from Humphreys (1978ApJS...38..309H), Elias et al. (1985ApJS...57...91E), Jura & Kleinmann (1990ApJS...73..769J), and Levesque et al. (2005ApJ...628..973L). Infrared and optical measurements from the Two Micron All Sky Survey, Catalog of Infrared Observations (CIO), Midcourse Space Experiment, Wide-field Infrared Survey Explorer, MIPSGAL, Galactic Legacy Infrared Midplane Extraordinaire (GLIMPSE), and The Naval Observatory Merged Astrometric Dataset catalogs allow us to estimate the stellar bolometric magnitudes. We analyze the stars in the luminosity versus effective temperature plane and confirm that 43 sources are highly probably RSGs with M_bol_< -7.1 mag. Of the stars in the sample, 43% have masses >7 M_{sun}_. Another ~30% of the sample consists of giant stars.

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