Planetary host stars : evaluating uncertainties in cool model atmospheres
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M-dwarfs are emerging in the literature as promising targets for detecting low-mass, Earth-like planets. An important step in this process is to determine the stellar parameters of the M-dwarf host star as accurately as possible. Different well-tested stellar model atmosphere simulations from different groups are widely applied to undertake this task. This paper provides a comparison of different model atmosphere families to allow a better estimate of systematic errors on host-star stellar parameter introduced by the use of one specific model atmosphere family only. We present a comparison of the ATLAS9, MARCS, PHOENIX and DRIFT-PHOENIX model atmosphere families including the M-dwarf parameter space (Teff = 2500-4000 K, log(g) = 3.0-5.0, [M/H] = -2.5to0.5). We examine the differences in the (Tgas, pgas)-structures, in synthetic photometric fluxes and in colour indices. Model atmospheres results for higher log(g) deviate considerably less between different models families than those for lower log(g) for all Teff = 2500-4000 K examined. We compiled the broad-band synthetic photometric fluxes for all available model atmospheres (incl. M-dwarfs and brown dwarfs) for the UKIRT WFCAM ZYJHK, 2MASS JHKs and Johnson UBVRI filters, and calculated related colour indices. Synthetic colours in the IR wavelengths diverge by no more than 0.15 dex amongst all model families. For all spectral bands considered, model discrepancies in colour diminish for higher Teff atmosphere simulations. We notice differences in synthetic colours between all model families and observed example data (including Kepler 42 and GJ1214).
Bozhinova , I , Helling , C & Scholz , A 2015 , ' Planetary host stars : evaluating uncertainties in cool model atmospheres ' Monthly Notices of the Royal Astronomical Society , vol 450 , no. 1 , pp. 160-182 . DOI: 10.1093/mnras/stv613
Monthly Notices of the Royal Astronomical Society
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
ChH highlights financial support of the European Community under the FP7 by an ERC starting grant. IB thanks the Physics Trust of the University of St Andrews for supporting her summer placement.
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