- ID:
- ivo://CDS.VizieR/J/A+A/537/A105
- Title:
- Modelisation of AGB stars in the LMC
- Short Name:
- J/A+A/537/A105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asymptotic giant branch (AGB) stars are major contributors to both the chemical enrichment of the interstellar medium and the integrated light of galaxies. Despite its importance, the AGB is one of the least understood phases of stellar evolution. The main difficulties associated with detailed modelling of the AGB are related to the mass-loss process and the 3rd dredge-up efficiency. We provide direct measures of mass-loss rates and luminosities for a complete sample of AGB stars in the Large Magellanic Cloud, disentangling the C- and O-rich stellar populations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/506/1277
- Title:
- Modelisation of Magellanic Cloud C/O stars
- Short Name:
- J/A+A/506/1277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass loss is one of the fundamental properties of Asymptotic Giant Branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. To investigate the relation between mass loss, luminosity and pulsation period for a large sample of evolved stars in the Small and Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/661/250
- Title:
- Molecular line survey of CRL 618
- Short Name:
- J/ApJ/661/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete data set, model, and line identification of a survey of the emission from the C-rich proto-planetary nebula CRL 618 performed with the IRAM 30m telescope in the frequency ranges 80.25-115.75GHz, 131.25-179.25GHz, and 204.25-275.250GHz. A selection of lines from different species has been used in previous works to derive the structure of the source, its physical conditions, and the chemical abundances in the different gas regions. In this work, we have used this information to run a global simulation of the spectrum in order to check the consistency of the model and to ease the task of line identification. The total number of lines that have a correspondence in both data and model is ~3100, although quite often in this object many lines blend into complex features, so that the model, which takes into account line blending, is a key tool at this stage of the analysis. Of all the lines that we have been able to label, ~55% of them belong to the different forms of HC3N, and ~18% to HC5N. The density of remaining unidentified features above the 3sigma limit is only 1 per ~2.1GHz (74 features), which is unprecedented in the analysis of this type of large millimeter-wave line surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/416/787
- Title:
- Mount Wilson Crv Metallicity index
- Short Name:
- J/ApJ/416/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/AJ/124/234
- Title:
- M31 outer halo UBVRI photometry and metallicity
- Short Name:
- J/AJ/124/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10m telescope and Low Resolution Imaging Spectrograph of the Ca II near-infrared triplet in 99 M31 halo candidates in a field at R=19kpc on the southeast minor axis with brightnesses from 20<I<22.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/1812
- Title:
- M54 red giants abundances
- Short Name:
- J/MNRAS/444/1812
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cosmological Li problem is the observed discrepancy between Li abundance (A(Li)) measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)_0_), and that predicted by standard big bang nucleosynthesis (BBN) calculations (A(Li)_BBN_). Here, we attack the Li problem by considering an alternative diagnostic, namely the surface Li abundance of red giant branch stars that in a colour-magnitude diagram populate the region between the completion of the first dredge-up and the red giant branch bump. We obtained high-resolution spectra with the FLAMES facility at the Very Large Telescope for a sample of red giants in the globular cluster M54, belonging to the Sagittarius dwarf galaxy. We obtain A(Li)=0.93+/-0.11dex, translating - after taking into account the dilution due to the dredge-up - to initial abundances (A(Li)_0_) in the range 2.35-2.29 dex, depending on whether or not atomic diffusion is considered. This is the first measurement of Li in the Sagittarius galaxy and the more distant estimate of A(Li)_0_ in old stars obtained so far. The A(Li)_0_ estimated in M54 is lower by ~0.35dex than A(Li)_BBN_, hence incompatible at a level of ~3{sigma}. Our result shows that this discrepancy is a universal problem concerning both the Milky Way and extragalactic systems. Either modifications of BBN calculations, or a combination of atomic diffusion plus a suitably tuned additional mixing during the main sequence, need to be invoked to solve the discrepancy.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/8
- Title:
- M-type stars in LAMOST DR5
- Short Name:
- J/ApJS/244/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new catalogs of M giant and M dwarf stars from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data release 5 (DR5). In total, 39796 M giants and 501152 M dwarfs are identified from the classification pipeline. The template-fitting results contain M giants with 7 temperature subtypes from M0 to M6, M dwarfs with 18 temperature subtypes from K7.0 to M8.5, and 12 metallicity subclasses from dMr to usdMp. We cross-matched our M-type catalog with the Two Micron All-Sky Survey (2MASS) and Wide-field Infrared Survey Explorer (WISE) catalog to obtain infrared magnitude and colors. Adopting the distances derived from the parallaxes in Gaia DR2, the M_G_ versus (G_bp_-G_rp_)_0_ diagram shows that there are also early-type stars and white dwarf-M dwarf binaries included in our M-type stars sample, with a contamination rate of about 4.6% for M giants and 0.48% for M dwarfs. We found that CaH spectral indices are an efficient selection criteria for carbon stars. A total of 289 carbon stars were identified from the M giants sample, and further confirmed by LAMOST spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A29
- Title:
- Multiplicity of red supergiants in NGC 330
- Short Name:
- J/A+A/635/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The multiplicity properties of massive stars are one of the important outstanding issues in stellar evolution. Quantifying the binary statistics of all evolutionary phases is essential to paint a complete picture of how and when massive stars interact with their companions, and to determine the consequences of these interactions. We investigate the multiplicity of an almost complete census of red supergiant stars (RSGs) in NGC 330, a young massive cluster in the Small Magellanic Cloud. Using a combination of multi-epoch HARPS and MUSE spectroscopy, we estimate radial velocities and assess the kinematic and multiplicity properties of 15 RSGs in NGC 330. Radial velocities are estimated to better than +/-100m/s for the HARPS data. The line-of-sight velocity dispersion for the cluster is estimated as {sigma}_1D_=3.20^+0.69^_-0.52_km/s. When virial equilibrium is assumed, the dynamical mass of the cluster is log(M_dyn_/M_{sun}_)=5.20+/-0.17, in good agreement with previous upper limits. We detect significant radial velocity variability in our multi-epoch observations and distinguish between variations caused by atmospheric activity and those caused by binarity. The binary fraction of NGC 330 RSGs is estimated by comparisons with simulated observations of systems with a range of input binary fractions. In this way, we account for observational biases and estimate the intrinsic binary fraction for RSGs in NGC 330 as f_RSG_=0.3+/-0.1 for orbital periods in the range 2.3<logP[days]<4.3, with q>0.1. Using the distribution of the luminosities of the RSG population, we estimate the age of NGC 330 to be 45+/-5Myr and estimate a red straggler fraction of 50%. We estimate the binary fraction of RSGs in NGC 330 and conclude that it appears to be lower than that of main-sequence massive stars, which is expected because interactions between an RSG and a companion are assumed to effectively strip the RSG envelope.
- ID:
- ivo://CDS.VizieR/III/25A
- Title:
- Na, Mg, Ca abundances in K-type giants
- Short Name:
- III/25A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Narrow-band photometric measures of the strengths of the Mg b, Ca triplet, and Na D lines on 312 G and K type giant stars have been analysed with a model atmosphere technique to determine abundances of Mg, Ca and Na.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A51
- Title:
- Near-IR photometry of AGB stars in IC 1613
- Short Name:
- J/A+A/578/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated the photometric properties of asymptotic giant branch (AGB) stars of dwarf irregular galaxy IC 1613 and its metallicity. We used near-infrared JHKs photometric data obtained with the WIRCam array on Canada-France-Hawaii Telescope (CHFT). The optical gi imaging data of previous study were cross-matched with ours to distinguish the stellar populations in the galaxy and to select the AGB stars. We also separated the C stars from the M-giant stars in the JHKs color-color diagram. We identified 140 C stars and 306 M-giant stars in IC 1613. The (J-Ks) color histogram of AGB stars shows the main peak of M-giant stars and the red tail of C stars. The broad color distribution of M-giant stars and the isochrones in color magnitude diagram indicate that IC 1613 has a wide range of intermediate-age stars. We also know that most C stars were formed over the past 2-8Gyr according the M_bol-age relation. The C/M ratio of 0.46+/-0.05 was estimated and [Fe/H] abundance of -1.23+/-0.06 was derived from the C/M ratio. Radial distributions of C/M ratio and metallicity show the shallow trend of the negative metallicity gradient from the center. The local C/M ratio also indicates that the HI cavity has higher C/M values than the bright HI spot and HI gas region. However, the low [Fe/H] value near the central region of the galaxy is likely to be caused by the change in age of the dominant stellar population according to the radial distance, not the real metallicity variation. It might also be that relatively younger and metal-rich C stars are concentrated in the center of the galaxy, while the M-giant stars were homogeneously distributed from the center to the borders of the galaxy.
