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We present high-resolution optical spectra of the young brown-dwarf eclipsingbinary 2M0535-05, obtained during eclipse of the higher-mass (primary) browndwarf. Combined with our previous spectrum of the primary alone (Paper I), thenew observations yield the spectrum of the secondary alone. We investigate,through a differential analysis of the two binary components, whether coolsurface spots are responsible for suppressing the temperature of the primary.In Paper I, we found a significant discrepancy between the empirical surfacegravity of the primary and that inferred via fine analysis of its spectrum.Here we find precisely the same discrepancy in surface gravity, bothqualitatively and quantitatively. While this may again be ascribed to eithercool spots or model opacity errors, it implies that cool spots cannot beresponsible for preferentially lowering the temperature of the primary: if theywere, spot effects on the primary spectrum should be preferentially larger, andthey are not. The Teff we infer for the primary and secondary, from theTiO-epsilon bands alone, show the same reversal, in the same ratio, as isempirically observed, bolstering the validity of our analysis. In turn, thisimplies that if suppression of convection by magnetic fields on the primary isthe fundamental cause of the Teff reversal, then it cannot be a localsuppression yielding spots mainly on the primary (though both components may beequally spotted), but a global suppression in the interior of the primary. Webriefly discuss current theories of how this might work.

astrophysical journal/the astrophysical journal

High-Resolution Spectroscopy during Eclipse of the Young Substellar  Eclipsing Binary 2MASS 0535-0546. II. Secondary Spectrum: No Evidence that  Spots Cause the Temperature Reversal