Improving PARSEC models for very low mass stars

By Yang Chen, L. Girardi, A. Bressan, P. Marigo, M. Barbieri, X. Kong. 2014

465 citations recorded by the source corpus.

Many stellar models present difficulties in reproducing basic observational relations of very low mass stars (VLMS), including the mass--radius relation and the optical colour--magnitudes of cool dwarfs. Here, we improve PARSEC models on these points. We implement the T--tau relations from PHOENIX BT-Settl model atmospheres as the outer boundary conditions in the PARSEC code, finding that this change alone reduces the discrepancy in the mass--radius relation from 8 to 5 per cent. We compare the models with multi--band photometry of clusters Praesepe and M67, showing that the use of T--tau relations clearly improves the description of the optical colours and magnitudes. But anyway, using both Kurucz and PHOENIX model spectra, model colours are still systematically fainter and bluer than the observations. We then apply a shift to the above T--tau relations, increasing from 0 at T_eff = 4730 K to ~14% at T_eff = 3160 K, to reproduce the observed mass--radius radius relation of dwarf stars. Taking this experiment as a calibration of the T--tau relations, we can reproduce the optical and near infrared CMDs of low mass stars in the old metal--poor globular clusters NGC6397 and 47Tuc, and in the intermediate--age and young solar--metallicity open clusters M67 and Praesepe. Thus, we extend PARSEC models using this calibration, providing VLMS models more suitable for the lower main sequence stars over a wide range of metallicities and wavelengths. Both sets of models are available on PARSEC webpage.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/aef5e93d4a171f5a15dce01ee4080704013c92c8

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In Astronomy and Astrophysics

1. Michela Mapelli
2. C. Conroy
3. Mario Spera
4. O. Gerhard
5. I. Minchev
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In Instrumentation

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Citations in the corpus

• The mass spectrum of compact remnants from the parsec stellar evolution tracks (2015, methodology): “…for ‘Stellar EVolution N -body’), a new population synthesis tool that couples PARSEC evolutionary tracks for stellar evolution (Bressan et al. 2012; Chen et al. 2014; Tang et al. 2014) with up-to-date models for SN explosion (Fryer et al. 2012; Janka 2012; Ertl et al. 2015), and that can be…”
• The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, methodology): “An isochrone grid is constructed using the Padova isochrones4 (see Bressan et al. 2012, Chen et al. 2014, Chen et al. 2015, Tang et al. 2014).”
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood (2015, unknown): “2S models by Chen et al. (2014).”
• The biggest splash (2019, methodology): “The data were compared to a grid of PARSEC isochrone models (Bressan et al. 2012; Chen et al. 2014; Tang et al. 2014; Chen et al. 2015) in a probabilistic sense.”
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 (2019, methodology): “In this work we used a grid of PARSEC 1.2S stellar models (Bressan et al. 2012; Chen et al. 2014; Tang et al. 2014) in the 2MASS, Pan-STARRS1, Gaia DR2 rederived (Maíz Apellániz & Weiler 2018), and WISE photometric systems available on the CMD webpage maintained by L. Girardi5.”
• PARSEC evolutionary tracks of massive stars up to 350 M ☉ at metallicities 0.0001 ≤ Z ≤ 0.04 (2015, methodology): “These tables for cool stars have already been used in Chen et al. (2014), in the context of low and very low mass stars.”
• The Updated BaSTI Stellar Evolution Models and Isochrones. I. Solar-scaled Calculations (2018, methodology): “We considered the non-rotating MIST isochrones, and the PARSEC isochrones with VLM stellar models calculated with the ‘calibrated’ boundary conditions, as described in Chen et al. (2014).”
• ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, methodology): “We calculate a photometric distance to K2-33 of 140±16 pc using literature optical and NIR photometry, and the 10 Myr isochrone from Chen et al. (2014).”
• How to Constrain Your M Dwarf. II. The Mass–Luminosity–Metallicity Relation from 0.075 to 0.70 Solar Masses (2018, result): “While other model grids (e.g.,YaPSI, PARSEC, Lyon Spada et al. 2013; Chen et al. 2014; Baraffe et al. 2015) show similar agreement with empirical studies of low-mass stars, we leave a more detailed comparison between the full range of model grids and our empirical masses for future analysis, and we…”
• HOW TO CONSTRAIN YOUR M DWARF: MEASURING EFFECTIVE TEMPERATURE, BOLOMETRIC LUMINOSITY, MASS, AND RADIUS (2015, background): “…of similar magnitude among standard stellar evolution models that adopt appropriate physics for the physical conditions in these objects (e.g., Lyon, Dartmouth, Yale, Pisa, and Padova models; Feiden & Chaboyer 2012a; Boyajian et al. 2012b; Spada et al. 2013; Chen et al. 2014; Torres et al. 2014).”
• A RADIAL AGE GRADIENT IN THE GEOMETRICALLY THICK DISK OF THE MILKY WAY (2016, methodology): “We test this using the PARSEC isochrones (Chen et al. 2014) combined with a Chabrier initial mass function (IMF).”
• The star formation history and accretion-disc fraction among the K-type members of the Scorpius–Centaurus OB association (2016, methodology): “We use the Dartmouth models (Dotter et al. 2008), the Pisa models (Tognelli et al. 2011), the PARSEC models (Chen et al. 2014), and the Exeter/Lyon models (Baraffe et al. 2015).”
• A NEW GENERATION OF PARSEC-COLIBRI STELLAR ISOCHRONES INCLUDING THE TP-AGB PHASE (2017, background): “Further updates regard the treatment of boundary conditions in low-mass stars (Chen et al. 2014), and envelope overshooting and mass-loss in intermediate- and high-mass stars (Tang et al. 2014; Chen et al. 2015).”
• Dynamical modelling of the galactic bulge and bar: the Milky Way's pattern speed, stellar and dark matter mass distribution (2016, methodology): “…of every star using the surface gravity logg measurement obtained from fitting the spectra together with the PARSEC isochrones (Bressan et al. 2012; Chen et al. 2014; Tang et al. 2014) and assuming a 10Gyr old population, a Kroupa IMF and the overall metallicity distribution of all the ARGOS stars.”
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star-forming dwarf galaxies (2014, methodology): “The outer boundary conditions are discussed in Chen et al. (2014).”
• Age determination for 269 Gaia DR2 open clusters (2019, methodology): “2S with the bolometric corrections described by Chen et al. (2014).”
• MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, background): “The former is likely mostly due to differences in the adopted boundary conditions in the models, and the latter is possibly due to differences in the adopted Reimers mass loss efficiency (BaSTI, PARSEC, and MIST adopt ηR = 0.4, 0.2, and 0.1, respectively, while Y2 does not include mass loss).”