Abstract
We present empirical relations for determining the amount by which the
effective temperatures and radii---and therefore the estimated
masses---of low-mass stars and brown dwarfs are altered due to
chromospheric activity. Accurate estimates of stellar radii are
especially important in the context of searches for transiting
exoplanets, which rely upon the assumed stellar radius/density to infer
the planet radius/density. Our relations are based on a large set of
well studied low-mass stars in the field and on a set of benchmark
low-mass eclipsing binaries. The relations link the amount by which an
active object's temperature is suppressed, and its radius inflated, to
the strength of its Halpha emission. These relations are found to
approximately preserve bolometric luminosity. We apply these relations
to the peculiar brown-dwarf eclipsing binary 2M0535-05, in which the
active, higher-mass brown dwarf has a cooler temperature than its
inactive, lower-mass companion. The relations correctly reproduce the
observed temperatures and radii of 2M0535-05 after accounting for the
Halpha emission; 2M0535-05 would be in precise agreement with
theoretical isochrones were it inactive. The relations that we present
are applicable to brown dwarfs and low-mass stars with masses below 0.8
Msun and for which the activity, as measured by Halpha, is in the range
-4.6 <log Lha/Lbol <-3.3. We expect these relations to be most
useful for correcting radius and mass estimates of low-mass stars and
brown dwarfs over their active lifetimes (few Gyr). We also discuss the
implications of this work for determinations of young cluster IMFs.
Original language | English |
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Article number | 1756 |
Journal | ArXiv e-prints |
Volume | 1209 |
Publication status | Published - 1 Sept 2012 |
Keywords
- Astrophysics - Solar and Stellar Astrophysics