M dwarfs: effective temperatures, radii and metallicities

By Luca Casagrande, Chris Flynn, M. Bessell. 2008

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We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for late-type dwarfs extends well below 3000 K (almost to the brown dwarf limit) and is supported by interferometric angular diameter measurements above 3000 K. Our metallicities are in excellent agreement (usually within 0.2 dex) with recent determinations via independent techniques. A subsample of cool M dwarfs with metallicity estimates based on hotter Hipparcos common proper motion companions indicates our metallicities are also reliable below 3000 K, a temperature range unexplored until now. The high quality of our data allows us to identify a striking feature in the bolometric luminosity versus temperature plane, around the transition from K to M dwarfs. We have compared our sample of stars with theoretical models and conclude that this transition is due to an increase in the radii of the M dwarfs, a feature which is not reproduced by theoretical models.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/c5eb44c54cd93b512976fa3258e2cb5af837d64e

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Citations in the corpus

PLANETARY CANDIDATES FROM THE FIRST YEAR OF THE K2 MISSION (2015, methodology): “…then estimated the stellar effective temperature for each target from the star’s colors using either empirical relations from Boyajian et al. (2013), Casagrande et al. (2008), or González Hernández & Bonifacio (2009), or by interpolating color temperature relations from Eric Mamajek’s spectral…”
MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, background): “…between observed and predicted effective temperature, radius, and luminosity relations for stars with appreciable convective layers, most notably M dwarfs (e.g., Casagrande et al. 2008; Torres et al. 2010; Kraus et al. 2011; Feiden & Chaboyer 2013; Spada et al. 2013; Torres 2013; Chen et al. 2014).”
COUNTING LOW-MASS STARS IN INTEGRATED LIGHT (2011, methodology): “For dwarfs we adopt the new Teff scale from Casagrande et al. (2008, 2010).”
HOW TO CONSTRAIN YOUR M DWARF: MEASURING EFFECTIVE TEMPERATURE, BOLOMETRIC LUMINOSITY, MASS, AND RADIUS (2015, methodology): “While the more recent CIFIST version reproduces the Teff scale from LBOI determinations, the older versions (i.e., the best available to Casagrande et al. 2008) differ systematically from LBOI-derived Teff values (Mann et al. 2013b).”
THE OCCURRENCE RATE OF SMALL PLANETS AROUND SMALL STARS (2013, background): “We set the metallicity prior by assuming that the metallicity distribution of the M dwarfs in the Kepler target list is similar to the metallicity distribution of the 343 nearby M dwarfs studied by Casagrande et al. (2008).”
The effective temperature scale of M dwarfs (2013, methodology): “More recently, Casagrande et al. (2008) used thePHOENIX Cond-GAIA model atmosphere grid (P. H. Hauschildt, unpublished) to determine the atmospheric parameters of their sample of 343 nearby M dwarfs with high-quality optical and IR photometry.”
AN EMPIRICAL CALIBRATION TO ESTIMATE COOL DWARF FUNDAMENTAL PARAMETERS FROM H-BAND SPECTRA (2014, methodology): “…Street, Cambridge, MA 02138, USA 2 Astronomy Department, University of Texas at Austin, Austin, TX 78712, USA other technique that can be used is the infrared flux method (IRFM; Blackwell & Shallis 1977; Blackwell et al. 1979, 1980), which was extended to M dwarfs by Casagrande et al. (2008).”
CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS (2015, methodology): “…techniques employed to determine metallicityn M dwarfs: – Photometry calibrated with M dwarfs in physical double and multiple systems with warmer companions, typically F, G, K dwarfs, of known metallicity (Bonfils et al. 2005; Casagrande et al. 2008; Schlaufman & Laughlin 2010; Neves et al. 2012).”
SWEET-Cat: A catalogue of parameters for Stars With ExoplanETs - I. New atmospheric parameters and masses for 48 stars with planets (2013, methodology): “The uncertainty in Teff for the Casagrande et al. (2008) was computed by adding the propagation of the errors of the V and infrared photometry (Skrutskie et al. 2006) taken to calculate the calibrations with the estimated Article number, page 9 of 12 error of the calibration (150 K).”
INTRINSIC COLORS, TEMPERATURES, AND BOLOMETRIC CORRECTIONS OF PRE-MAIN-SEQUENCE STARS (2013, methodology): “Casagrande et al. (2008) assumed log(g)=5.0 dex throughout with the ‘Cond’ variant of NextGen models (we have used the ‘BT-Settl’ variant here with revised solar abundances from Asplund et al. 2009), whereas the Casagrande et al. (2011) study used the Castelli & Kurucz (2004) models which used the…”
BAYESIAN ANALYSIS TO IDENTIFY NEW STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS (2012, methodology): “The I -band photometric data come from the DENIS and SDSS-DR8 catalogs and several other studies (Torres et al. 2006; Reid & Cruz 2002; Koen et al. 2010; Casagrande et al. 2008; Reid et al. 2003, 2004, Riedel (in prep)).”
An absolutely calibrated T eff scale from the infrared flux method. Dwarfs and subgiants (2010, background): “4 Casagrande et al.: The eff ctive temperature scale: resolving different versions Casagrande et al. (2008), but this is outside the purpose of the present paper.”
The Evolution of L and T Dwarfs in Color-Magnitude Diagrams (2008, methodology): “In addition to the input mass and age distributions, the synthetic population is drawn from the observed distribution inmetallicity of 253Mdwarfs (Casagrande et al. 2008) spanning 0:9 ½M/H 0:3 with an average of 0:20 0:22.”
IDENTIFYING THE YOUNG LOW-MASS STARS WITHIN 25 PC. I. SPECTROSCOPIC OBSERVATIONS (2009, background): “…& Wallerstein 2005, [4] Nidever et al. 2002, [5] Reid et al. 2002b, and [6] Marcy & Benitz 1989. c As discussed in the text, Johnson & Apps (2009) have shown that [Fe/H] determinations using the Bonfils et al. (2005), and thus the Casagrande et al. (2008), calibration are strongly underestimated.”
Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes (2016, methodology): “Numerous calibrations of Teff for stars in various color/mass/age ranges have been performed (see, e.g., Casagrande et al. 2008, 2010; Boyajian et al. 2012, 2013; Mann et al. 2015), and thus while there remain systematic uncertainties, in general these uncertainties are well characterized and they…”
Homogeneous studies of transiting extrasolar planets – IV. Thirty systems with space-based light curves (2011, methodology): “Johnson et al. (2011) obtainTeff = 3130 ± 20K for component A from the calculatedV and observedKs magnitudes of the star applied to the photometric calibrations of Casagrande et al. (2008).”