- ID:
- ivo://CDS.VizieR/J/A+A/354/169
- Title:
- Metal-poor field stars abundances
- Short Name:
- J/A+A/354/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined Li, C, N, O, Na, and Fe abundances, and ^12^C/^13^C isotopic ratios for a sample of 62 field metal-poor stars in the metallicity range -2<=[Fe/H]<=-1. Stars were selected in order to have accurate luminosity estimates from the literature, so that evolutionary phases could be clearly determined for each star. We further enlarged this dataset by adding 43 more stars having accurate abundances for some of these elements and similarly well defined luminosities from the literature.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PASJ/33/107
- Title:
- M giants in Cassiopeia
- Short Name:
- J/PASJ/33/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Coordinates and identifications for M-type stars in Cassiopeia
- ID:
- ivo://CDS.VizieR/J/MNRAS/337/519
- Title:
- M giants in MACHO, DENIS and ISOGAL
- Short Name:
- J/MNRAS/337/519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A 'complete' sample of 174 M giants classified in the mid-1980s by Blanco (1986AJ.....91..290B) and later than subtype M0 in the NGC 6522 Baade's Window clear field has been investigated to establish some general properties of cool bulge stars. Photometric information has been obtained from the MACHO data base to search for variability and, where possible, to determine periods. Near- and mid-infrared magnitudes have been extracted from DENIS (<B/denis>) and ISOGAL (<II/243>). 46 semiregular variables (SRVs) and two irregular variables were found amongst the 174. Many M5 and all stars M6 or later show variation, whereas earlier subtypes (M1-M4) do not.
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.1154
- Title:
- M-giant star candidates in LAMOST DR 1
- Short Name:
- J/other/RAA/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a discrimination procedure with the spectral index diagram of TiO_5_ and CaH_2_+CaH_3_ to separate M giants from M dwarfs. Using the M giant spectra identified from LAMOST DR1 with high signal-to-noise ratio, we have successfully assembled a set of M giant templates, which show more reliable spectral features. Combining with the M dwarf/subdwarf templates in Zhong et al. (2015AJ....150...42Z, Cat. J/AJ/150/42), we present an extended library of M-type templates which includes not only M dwarfs with a well-defined temperature and metallicity grid but also M giants with subtypes from M0 to M6. Then, the template-fitting algorithm is used to automatically identify and classify M giant stars from LAMOST DR1. The resulting catalog of M giant stars is cross-matched with 2MASS JHKs and WISE W1/W2 infrared photometry. In addition, we calculated the heliocentric radial velocity of all M giant stars by using the cross-correlation method with the template spectrum in a zero-velocity rest frame. Using the relationship between the absolute infrared magnitude MJ and our classified spectroscopic subtype, we derived the spectroscopic distance of M giants with uncertainties of about 40%. A catalog of 8639 M giants is provided. As an additional result of this analysis, we also present a catalog of 101690 M dwarfs/subdwarfs which are processed by our classification pipeline.
- ID:
- ivo://CDS.VizieR/J/AJ/160/18
- Title:
- M giant stars asteroseismology with Kepler and APOGEE
- Short Name:
- J/AJ/160/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Evolved stars near the tip of the red giant branch show solar-like oscillations with periods spanning hours to months and amplitudes ranging from ~1mmag to ~100mmag. The systematic detection of the resulting photometric variations with ground-based telescopes would enable the application of asteroseismology to a much larger and more distant sample of stars than is currently accessible with space-based telescopes such as Kepler or the ongoing Transiting Exoplanet Survey Satellite mission. We present an asteroseismic analysis of 493 M giants using data from two ground-based surveys: the Asteroid Terrestrial-impact Last Alert System (ATLAS) and the All-Sky Automated Survey for Supernovae (ASAS-SN). By comparing the extracted frequencies with constraints from Kepler, the Sloan Digital Sky Survey Apache Point Observatory Galaxy Evolution Experiment, and Gaia we demonstrate that ground-based transient surveys allow accurate distance measurements to oscillating M giants with a precision of ~15%. Using stellar population synthesis models we predict that ATLAS and ASAS-SN can provide asteroseismic distances to ~2x106 galactic M giants out to typical distances of 20-50kpc, vastly improving the reach of Gaia and providing critical constraints for Galactic archeology and galactic dynamics.
- ID:
- ivo://CDS.VizieR/J/AJ/128/245
- Title:
- M giant stars in the Sagittarius dwarf galaxy
- Short Name:
- J/AJ/128/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained moderate resolution (~6km/s) spectroscopy of several hundred M giant candidates selected from Two Micron All Sky Survey photometry (Cat. <II/246>). Radial velocities are presented for stars mainly in the southern Galactic hemisphere, and the primary targets have Galactic positions consistent with association to the tidal tail system of the Sagittarius (Sgr) dwarf galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/670/346
- Title:
- M giant stars in the Sagittarius dwarf galaxy. V.
- Short Name:
- J/ApJ/670/346
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present reliable measurements of the metallicity distribution function (MDF) at different points along the tidal stream of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy, based on high-resolution, echelle spectroscopy of candidate M giant members of the Sgr system.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A56
- Title:
- Mid-infrared diameter of 4 AGBs
- Short Name:
- J/A+A/545/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asymptotic giant branch (AGB) stars are one of the largest distributors of dust into the interstellar medium. However, the wind formation mechanism and dust condensation sequence leading to the observed high mass-loss rates have not yet been constrained well observationally, in particular for oxygen-rich AGB stars. The immediate objective in this work is to identify molecules and dust species which are present in the layers above the photosphere, and which have emission and absorption features in the mid-infrared (IR), causing the diameter to vary across the N- band, and are potentially relevant for the wind formation. Mid-IR (8-13 micron) interferometric data of four oxygen-rich AGB stars (R Aql, R Aqr, R Hya, and W Hya) and one carbon-rich AGB star (V Hya) were obtained with MIDI/VLTI between April 2007 and September 2009. The spectrally dispersed visibility data are analyzed by fitting a circular fully limb-darkened disk (FDD). The FDD diameter as function of wavelength is similar for all oxygen-rich stars. The apparent size is almost constant between 8 and 10 micron and gradually increases at wavelengths longer than 10 micron. The apparent FDD diameter in the carbon-rich star V Hya essentially decreases from 8 to 12 micron. The FDD diameters are about 2.2 times larger than the photospheric diameters estimated from K-band observations found in the literature. The silicate dust shells of R Aql, R Hya and W Hya are located fairly far away from the star, while the silicate dust shell of R Aqr and the amorphous carbon (AMC) and SiC dust shell of V Hya are found to be closer to the star at around 8 photospheric radii. Phase-to-phase variations of the diameters of the oxygen-rich stars could be measured and are on the order of 15% but with large uncertainties. From a comparison of the diameter trend with the trends in RR Sco and S Ori it can be concluded that in oxygen-rich stars the overall larger diameter originates from a warm molecular layer of H2O, and the gradual increase longward of 10 micron can be most likely attributed to the contribution of a close Al2O3 dust shell. The chromatic trend of the Gaussian FWHM in V Hya can be explained with the presence of AMC and SiC dust. The observations suggest that the formation of amorphous Al2O3 in oxygen-rich stars occurs mainly around or after visual minimum. However, no firm conclusions can be drawn concerning the mass-loss mechanism. Future modeling with hydrostatic and self-consistent dynamical stellar atmospheric models will be required for a more certain understanding.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A83
- Title:
- Milky Way nuclear disk KMOS survey
- Short Name:
- J/A+A/649/A83
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In the central few degrees of the bulge of the Milky Way there is a flattened structure of gas, dust, and stars, known as the central molecular zone, that is similar to nuclear disks in other galaxies. As a result of extreme foreground extinction, we possess only sparse information about the (mostly old) stellar population of the nuclear disk. In this work we present our KMOS spectroscopic survey of the stars in the nuclear disk reaching the old populations. To obtain an unbiased data set, we sampled stars in the full extinction range along each line of sight. We also observed reference fields in neighboring regions of the Galactic bulge. We describe the design and execution of the survey and present first results. We obtain spectra and five spectral indices of 3113 stars with a median S/N of 67 and measure radial velocities for 3051 stars. Of those, 2735 sources have sufficient S/N to estimate temperatures and metallicities from indices. We derive metallicities using the CO 2-0 and Na I K-band spectral features, where we derive our own empirical calibration using metallicities obtained with higher-resolution observations.We use 183 giant stars for calibration spanning in metallicity from -2.5 to 0.6dex and covering temperatures of up to 5500K. The derived index based metallicities deviate from the calibration values with a scatter of 0.32dex. The internal uncertainty of our metallicities is likely smaller. We use these metallicity measurements, together with the CO index, to derive effective temperatures using literature relations. We publish the catalog in this paper. Our data set complements Galactic surveys such as Gaia and APOGEE for the inner 200pc radius of the Milky Way, which is not readily accessible by those surveys owing to extinction. We will use the derived properties in future papers for further analysis of the nuclear disk.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/44
- Title:
- Mira-like variables from the KELT survey
- Short Name:
- J/ApJS/247/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 4132 Mira-like variables (red variables with long periods and high amplitudes) in the Kilodegree Extremely Little Telescope (KELT) survey. Of these, 376 are new Mira-like detections. We used Two Micron All Sky Survey (2MASS) colors to identify candidate asymptotic giant branch stars. We searched for photometric variability among the candidate asymptotic giant branch stars and identified stars that show periodic variability. We selected variables with high amplitudes and strong periodic behavior using a Random Forest classifier. Of the sample of 4132 Mira-like variables, we estimate that 70% are Miras and 30% are semiregular (SR) variables. We also adopt the method of using (W_RP_-W_Ks_) versus (J-Ks) colors in distinguishing between O-rich and C-rich Miras and find it to be an improvement over 2MASS colors.
