- ID:
- ivo://CDS.VizieR/J/A+A/493/785
- Title:
- Galactic disk stellar populations from ISOGAL
- Short Name:
- J/A+A/493/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15um towards a field (LN45) in the direction l=-45, b=0.0. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory were characterised based on colour-colour and colour-magnitude diagrams. We combine the ISOGAL catalogue with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance were estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes were thus derived and the stellar populations identified from their absolute magnitudes and their infrared excess. A standard approach to analysing the ISOGAL disc observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16deg^2^. An overdensity of stellar sources is found at distances corresponding to the distance of the Scutum-Crux spiral arm. In addition, we determined mass-loss rates of AGB-stars using dust radiative transfer models from the literature.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1673
- Title:
- Galactic post-AGB stars distances
- Short Name:
- J/MNRAS/447/1673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Torun catalogue of Szczerba et al. (2007A&A...469..799S, Cat. J/A+A/469/799), and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are essential in determining meaningful physical characteristics for these sources and this has been difficult to determine for most objects previously. The distances were determined by modelling their spectral energy distributions (SEDs) with multiple blackbody curves, and integrating under the overall fit to determine the total distance-dependent flux. This approach was undertaken for consistency as precise spectral types, needed for more detailed fitting, were unknown in the majority of cases. The SED method works because the luminosity of these central stars is very nearly constant from the tip of the AGB phase to the beginning of the white dwarf cooling track. This then enables us to use a standard-candle luminosity to estimate the SED distances. For Galactic thin-disc PAGB objects, we use three luminosity bins based on typical observational characteristics, ranging between 3500 and 12000L_{sun}_. We further adopt a default luminosity of 4000L_{sun}_ for bulge objects and 1700L_{sun}_ for the thick-disc and halo objects. We have also applied the above technique to a further sample of 54 related nebulae not in the current edition of the Torun catalogue. In a follow-up paper, we will estimate distances to the subset of RV Tauri variables using empirical period-luminosity relations, and to the R CrB stars, allowing a population comparison of these objects with the other subclasses of PAGB stars for the first time.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A116
- Title:
- G and K giant stars stellar parameters
- Short Name:
- J/A+A/574/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3M_{sun}_, which is not being explored by main-sequence samples. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/20
- Title:
- 22GHz H_2_O maser survey toward IR sources
- Short Name:
- J/ApJ/769/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 22GHz H_2_O maser survey toward a new sample of asymptotic giant branch (AGB) and post-AGB star candidates. Most of the objects are selected for the first time based on the AKARI data, which have high flux sensitivity in the mid-infrared ranges. We aim at finding H_2_O maser sources in the transient phase between the AGB and post-AGB stages of evolution, where the envelopes start to develop large deviations from spherical symmetry. The observations were carried out with the Effelsberg 100m radio telescope. Among 204 observed objects, 63 detections (36 new) were obtained. We found four objects that may be "water fountain" sources (IRAS 15193+3132, IRAS 18056-1514, OH 16.3-3.0, and IRAS 18455+0448). They possess an H_2_O maser velocity coverage much smaller than those in other known water fountains. However, the coverage is still larger than that of the 1612MHz OH maser. It implies that there is an outflow with a higher velocity than the envelope expansion velocity (typically <=25km/s), meeting the criterion of the water fountain class. We suggest that these candidates are possibly oxygen-rich late AGB or early post-AGB stars in a stage of evolution immediately after the spherically symmetric AGB mass loss has ceased.
- ID:
- ivo://CDS.VizieR/J/AJ/89/636
- Title:
- Giant M stars in Baade's Window
- Short Name:
- J/AJ/89/636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared small-dispersion spectra obtained with a grism at the prime focus of CTIO's 4-m telescope have been used to survey and classify late-type red giants found in a circular area with a diameter of 24.4 arcmin which is contained within Baade's Window. The survey is complete to a distance that extends past the galactic nuclear bulge. The presented stars therefore constitute a unique complete sample of the red giant population of the nuclear bulge. A total of 306 red giants, including all giants of type M6 or later, are presented with a list of their coordinates, spectral classes, and apparent I magnitudes. A finding chart is also given. No C or S stars were found even though they should have been detected if they exist. Evidence is presented of uneven foreground interstellar obscuration in Baade's Window.
- ID:
- ivo://CDS.VizieR/J/A+A/603/L7
- Title:
- 6 giants atomic data and equivalent widths
- Short Name:
- J/A+A/603/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/MAGELLAN spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, {alpha}, proton- and neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H]=+0.00+/-0.01; {sigma}=0.03dex). All the other abundance ratios are generally solar-scaled, similar to the Galactic thin disk and open cluster stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, which can be considered as a standard Galactic open cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/100/1191
- Title:
- Giants DDO photometry
- Short Name:
- J/AJ/100/1191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of G and K giants approximately 4kpc from the Sun, covering the abundance range from solar to extreme halo has been selected without kinematic bias in a field aligned to measure galactic rotation. Accurate abundances, distances, and radial velocities have been measured. This sample has been combined with nonkinematically selected solar neighborhood objects taken from the literature, in order to examine the kinematics of the transition from disk to "thick disk" to halo. The metal-rich objects in the sample, with 0>[Fe/H]>-0.8, rotate rapidly around the galactic center and have low azimuthal velocity dispersion, {sigma}_{phi}_=40+/-10km/s. For objects in the range -0.5>[Fe/H]>-0.8, we find a small value for the asymmetric drift of 35+/-10km/s. We associate these objects with the thick disk, confirming the kinematical results of Ratnatunga and Freeman (1989, Cat.<V/65>) and others. In the abundance range -1.0>[Fe/H]>=-1.6 we find, in addition to objects with normal halo kinematics, objects in a disk configuration, confirming the results of Norris, Bessell, and Pickles (1985ApJS...58..463N). This disk is rotating rapidly, V_rot_=170+/-15km/s, and has a scale height of 1.4+/-0.7kpc, these kinematical and spatial properties are similar to those of the thick disk. We show that these objects have different kinematics from that of the globular clusters and a sample of local RR Lyraes in the same abundance range. This suggests to us that these objects are better associated with the thick disk than the halo, and we refer to them as "metal-weak thick-disk stars". Hence we suggest that the conventional chemical description of the thick disk (Gilmore and Wyse, 1985AJ.....90.2015G) be widened to include stars with abundances as low as [Fe/H]=-1.6. At the galactic plane, the density of these metal-weak thick-disk stars is similar to that of halo stars, so they significantly affect the measurement, from samples selected on abundance, of the components of the velocity ellipsoid for the halo in the solar neighborhood. For the halo giants in our sample we measure {sigma}_{phi}_=102+/-24 and V_rot_=17+/-24km/s. The rotation velocity and velocity ellipsoid for the metal-weak halo in the solar neighborhood have been rederived for objects with [Fe/H]<=-1.6 from the large sample of Norris (1986ApJS...61..667N), thus removing the possibility of contamination by metal-weak thick-disk stars. We derive V_rot_=25+/-15km/s and ({sigma}_r_, {sigma}_{phi}_, {sigma}_{theta}_)=(133+/-8, 98+/-13, 94+/-6)km/s. These values are more consistent with other information about the shape of the halo. For a description of the DDO photometric system, see e.g. <GCPD/12>
- ID:
- ivo://CDS.VizieR/J/A+A/658/A48
- Title:
- 7 giants/subgiants limb-darkening coefficients
- Short Name:
- J/A+A/658/A48
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Large spectroscopic surveys of the Milky Way need to be calibrated against a sample of benchmark stars to ensure the reliable determination of atmospheric parameters. Here we present new fundamental stellar parameters of seven giant and subgiant stars that will serve as benchmark stars for large surveys. The aim is to reach a precision of 1% in the effective temperature. This precision is essential for accurate determinations of the full set of fundamental parameters and abundances of stars observed by the stellar surveys. We observed HD121370 (eta Boo), HD161797 (mu Her), HD175955, HD182736, HD185351, HD188512 (beta Aql), and HD189349 using the high angular resolution optical interferometric instrument PAVO at the CHARA Array. The limb-darkening corrections were determined from 3D model atmospheres based on the STAGGER grid. The Teff were determined directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. We estimated surface gravities from comparisons to Dartmouth stellar evolution model tracks. The spectroscopic observations were collected from the ELODIE and FIES spectrographs. We estimated metallicities ([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE) abundance analysis of unblended lines of neutral and singly ionised iron. For six of the seven stars we measure Teff to better than 1%. For one star, HD189349, the uncertainty in Teff is 2% due to an uncertain bolometric flux. We do not recommend this star as a benchmark until this measurement can be improved. Median uncertainties for all stars in logg and [Fe/H]} are 0.034dex and 0.07dex, respectively. This study presents updated fundamental stellar parameters of seven giant and subgiant stars that can be used as a new set of benchmarks. All the fundamental stellar parameters were based on consistently combining interferometric observations, 3D limb-darkening modelling and spectroscopic analysis. This paper in this series follows our previous papers including dwarf stars and stars in the metal-poor range.
- ID:
- ivo://CDS.VizieR/J/AJ/151/7
- Title:
- Globular and open clusters observed by SDSS/SEGUE
- Short Name:
- J/AJ/151/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present griz observations for the clusters M92, M13 and NGC 6791 and gr photometry for M71, Be 29 and NGC 7789. In addition we present new membership identifications for all these clusters, which have been observed spectroscopically as calibrators for the Sloan Digital Sky Survey (SDSS)/SEGUE survey; this paper focuses in particular on the red giant branch stars in the clusters. In a number of cases, these giants were too bright to be observed in the normal SDSS survey operations, and we describe the procedure used to obtain spectra for these stars. For M71, we also present a new variable reddening map and a new fiducial for the gr giant branch. For NGC 7789, we derived a transformation from T_eff_ to g-r for giants of near solar abundance, using IRFM T_eff_ measures of stars with good ugriz and 2MASS photometry and SEGUE spectra. The result of our analysis is a robust list of known cluster members with correctly dereddened and (if needed) transformed gr photometry for crucial calibration efforts for SDSS and SEGUE.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A112
- Title:
- Halo oxygen-rich AGB stars catalog
- Short Name:
- J/A+A/626/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To construct a catalogue of oxygen-rich (M) asymptotic giant branch (AGB) stars in the halo, complementing the catalogues of carbon-rich (C) stars, previous lists of Miras and SRa semi-regulars located in the northern hemisphere are merged and cleaned of various defects. After putting aside known C stars, characteristics such as colours and periods indicate that most of the remaining objects are M stars. Distances are obtained through the period-luminosity relation. By considering their position in the sky, stars lying at |Z|>5kpc are confirmed to be in majority in the Sgr tidal arms. The M stars are more numerous than C ones. Our distance scale is supported by two cool variables located in the Pal 4 globular cluster. Along the Sgr arms, there is reasonable agreement on distances of our objects with recent RR Lyrae distances. A few stars may be as distant as 150kpc, with possibly four at the trailing arm apocentre, and two in the A16 sub-structure, angularly close to two C stars. Ninety radial velocities are collected from Gaia and other sources. A catalogue with 417 M pulsating AGB stars is provided. This catalogue contains about 260 stars in the halo with |Z|>5kpc. Their Ks magnitudes range from 8 up to 13. For comparison, the catalogue also provides about 150 stars in the disc having 5<Ks<8.
