J/ApJ/709/535 Masses and radii of ecliping binaries (Brown, 2010)
Radii of rapidly rotating stars, with application to transiting-planet hosts. Brown T.M. <Astrophys. J., 709, 535-545 (2010)> =2010ApJ...709..535B
ADC_Keywords: Binaries, eclipsing ; Models ; Planets ; Stars, masses ; Stars, diameters ; Stars, double and multiple Keywords: binaries: eclipsing - methods: data analysis - stars: fundamental parameters - stars: oscillations Abstract: The currently favored method for estimating radii and other parameters of transiting-planet host stars is to match theoretical models to observations of the stellar mean density ρ*, the effective temperature Teff, and the composition parameter [Z]. This explicitly model-dependent approach is based on readily available observations, and results in small formal errors. Its performance will be central to the reliability of results from ground-based transit surveys such as TrES, HAT, and SuperWASP, as well as to the space-borne missions MOST, CoRoT, and Kepler. Here, I use two calibration samples of stars (eclipsing binaries (EBs) and stars for which asteroseismic analyses are available) having well-determined masses and radii to estimate the accuracy and systematic errors inherent in the ρ* method. When matching to the Yonsei-Yale stellar evolution models, I find the most important systematic error results from selection bias favoring rapidly rotating (hence probably magnetically active) stars among the EB sample. If unaccounted for, this bias leads to a mass-dependent underestimate of stellar radii by as much as 4% for stars of 0.4M☉, decreasing to zero for masses above about 1.4M☉. Relative errors in estimated stellar masses are three times larger than those in radii. Description: I implemented the ρ* method, using the Yonsei-Yale evolution tracks (Yi et al. 2001ApJS..136..417Y; Kim et al. 2002ApJS..143..499K; Yi et al. 2003ApJS..144..259Y; Demarque et al. 2004ApJS..155..667D) as the needed stellar evolution models, and I then applied it to the Torres et al., (2009, Cat. J/other/A+ARV/18.67) tabulation of EBs and to 15 stars with asteroseismic measurements. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 83 156 *Eclipsing binary stars with accurate mass and radius estimates
Note on table1.dat: Data for masses, radii, Teff and [Z] are from Torres et al. (2009, Cat. J/other/A+ARV/18.67).
See also: V/121 : Catalog of DMS-type eclipsing binaries (Svechnikov+, 1999) V/118 : Catalog of eclipsing binaries parameters (Perevozkina+, 1999) J/A+A/526/A99 : Metal-poor solar-type stars spectroscopy and masses (Sousa+, 2011) J/A+A/527/A140 : Mass limits on substellar companions (Reffert+, 2011) J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010) J/ApJ/709/535 : Masses and radii of planet hosts (Brown, 2010) J/ApJ/694/1085 : Radii of exoplanet host stars (van Belle+, 2009) http://www.astro.yale.edu/demarque/yystar.html : Y2 (Yonsei-Yale) stellar models page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name Star name (binary name and component) 17- 21 F5.3 Msun Mass Mass of the star 23- 27 F5.3 Msun e_Mass rms on Mass 29- 34 F6.3 Rsun Rad Radius of the star 36- 40 F5.3 Rsun e_Rad rms on Rad 42- 46 I5 K Teff Effective temperature 48- 50 I3 K e_Teff rms on Teff 52- 57 F6.3 [Sun] [Z] ?=0 Logarithmic metal abundance relative to solar 59- 63 F5.3 [Sun] e_[Z] ?=0.2 rms uncertainty on [Z] 65- 69 F5.3 Msun Mfit Mass estimated by fit (1) 71- 76 F6.3 Rsun Rfit Radius estimated by fit (1) 78- 83 F6.2 Gyr Agefit Age estimated by fit (1)
Note (1): For each star, I applied the Markov Chain Monte Carlo (MCMC) procedure with the search over stellar models constrained by the star's mean density (computed from the Torres et al. 2009, mass and radius, see Cat. J/other/A+ARV/18.67), Teff, and [Z]. The MCMC/amoeba procedure then yielded new estimates of the stellar mass, radius, luminosity, age, mean density, Teff, and [Z], where the procedure necessarily returned values of the last three quantities that were much less than 1 standard deviation from those that were provided as input. The values of M*, R*, and A* derived by this method are listed in the last three columns (labeled "fit"). See text for further details.
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 02-Mar-2012
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