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Abstract
Context. To determine the physical parameters of a transiting planet and its host star from photometric and spectroscopic analysis, it is essential to independently measure the stellar mass. This is often achieved by the use of evolutionary tracks and isochrones, but the mass result is only as reliable as the models used.
Aims. The recent paper by Torres et al. (2010, A&ARv, 18, 67) showed that accurate values for stellar masses and radii could be obtained from a calibration using Teff, log g and [Fe/H]. We investigate whether a similarly good calibration can be obtained by substituting log ρ – the fundamental parameter measured for the host star of a transiting planet – for log g, and apply this to starexoplanet systems.Methods. We perform a polynomial fit to stellar binary data provided in Torres et al. (2010) to obtain the stellar mass and radius as functions of Teff, log ρ and [Fe/H], with uncertainties on the fit produced from a Monte Carlo analysis. We apply the resulting equations to measurements for seventeen SuperWASP host stars, and also demonstrate the application of the calibration in a Markov Chain Monte Carlo analysis to obtain accurate system parameters where spectroscopic estimates of effective stellar temperature and metallicity are available. Results. We show that the calibration using log ρ produces accurate values for the stellar masses and radii; we obtain masses and radii of the SuperWASP stars in good agreement with isochrone analysis results. We ascertain that the mass calibration is robust against uncertainties resulting from poor photometry, although a good estimate of stellar radius requires goodquality transit light curve to determine the duration of ingress and egress.
Aims. The recent paper by Torres et al. (2010, A&ARv, 18, 67) showed that accurate values for stellar masses and radii could be obtained from a calibration using Teff, log g and [Fe/H]. We investigate whether a similarly good calibration can be obtained by substituting log ρ – the fundamental parameter measured for the host star of a transiting planet – for log g, and apply this to starexoplanet systems.Methods. We perform a polynomial fit to stellar binary data provided in Torres et al. (2010) to obtain the stellar mass and radius as functions of Teff, log ρ and [Fe/H], with uncertainties on the fit produced from a Monte Carlo analysis. We apply the resulting equations to measurements for seventeen SuperWASP host stars, and also demonstrate the application of the calibration in a Markov Chain Monte Carlo analysis to obtain accurate system parameters where spectroscopic estimates of effective stellar temperature and metallicity are available. Results. We show that the calibration using log ρ produces accurate values for the stellar masses and radii; we obtain masses and radii of the SuperWASP stars in good agreement with isochrone analysis results. We ascertain that the mass calibration is robust against uncertainties resulting from poor photometry, although a good estimate of stellar radius requires goodquality transit light curve to determine the duration of ingress and egress.
Original language  English 

Article number  A33 
Number of pages  5 
Journal  Astronomy & Astrophysics 
Volume  516 
DOIs  
Publication status  Published  Jun 2010 
Keywords
 Planetary systems
 Photometric analysis
 Spectroscopic analysis
 Stellar mass
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Dive into the research topics of 'An improved method for estimating the masses of stars with transiting planets'. Together they form a unique fingerprint.Projects
 2 Finished

Astrophysics in St Andrews: Astrophysics in St Andrews / SUPA (Continuan of Rolling Grant  XPP089
Bonnell, I. A. (PI), Cameron, A. C. (CoI), Dominik, M. (CoI), Driver, S. P. (CoI), Greaves, J. S. (CoI), Horne, K. D. (CoI), Jardine, M. M. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
Science & Technology Facilities Council
1/04/09 → 31/03/12
Project: Standard

Wide Area Search for Planets: Project support for the Wide Area Search for Planets
Cameron, A. C. (PI)
Science & Technology Facilities Council
1/08/08 → 31/07/11
Project: Standard