Cool Stars 14 - Submitted Abstract # 87
This version created on 05 October 2006

Empirical Constraints on the Structure, Formation, and Evolution of
Young, Low-Mass Stars and Brown Dwarfs


Keivan Stassun, Vanderbilt University

We summarize current observational constraints on the internal
structure of young, low-mass stars and brown dwarfs.  Combining
empirically determined fundamental physical parameters (masses, radii,
temperatures, luminosities) with lithium abundances and X-ray tracers
of magnetic activity, we discuss the evidence for magnetically
suppressed convection in very young stars and brown dwarfs.  Using
recently discovered eclipsing binary stars and brown dwarfs as
exemplars, we discuss the possible effects of strong magnetic fields
on the ages derived from theoretical pre-main-sequence evolutionary
tracks, and discuss the implications for observational tests of star-
and brown-dwarf formation models.  For example, the recently
discovered brown-dwarf eclipsing binary 2M0535-05 exhibits a
surprising reversal of temperature with mass.  This can be taken as
evidence for non-coeval formation of the brown dwarfs---supporting
ejection models of brown dwarf formation---or as evidence of strong
magnetic fields altering energy transport in a coeval system.
Resolving these scenarios will thus be critical to calibrating
theoretical evolutionary tracks and stellar ages, and to testing
theories of brown dwarf formation mechanisms.

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