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Model Atmospheres and the Teff Scale for M Dwarfs

Published online by Cambridge University Press:  25 April 2016

John M. Brett  and
Bertrand Plez
John M. Brett
Affiliation:
Research Centre for Theoretical Astrophysics, University of Sydney, NSW 2006
Bertrand Plez
Affiliation:
University of Texas, Austin, Texas, USA
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Abstract

The Teff (effective temperature) scale for M dwarfs is very uncertain. One method which can be used to establish this scale is to compare observed spectra to synthetic ones derived from appropriate model atmospheres. With this method the adequacy of the model atmosphere is of great importance and simple models can give incorrect results. Alternatively if the Teff scale is known with some accuracy then this comparison is a good test of the adequacy of the models. We have computed some new and preliminary model atmospheres for late type dwarfs which accurately treat the line opacity with the opacity sampling technique and employ laboratory values for the transition strengths of molecular bands. With the above two considerations in mind we compare the fluxes of these models to observed fluxes of late K and early M dwarfs. This preliminary analysis indicates a discrepancy with the currently accepted Teff scale for early M dwarfs with the models suggesting values some 200 K hotter.

Type
Galactic and Stellar
Information
Publications of the Astronomical Society of Australia , Volume 10 , Issue 3 , 1993 , pp. 250 - 253
Copyright
Copyright © Astronomical Society of Australia 1993

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