Light curve of 2MASS J05352184-0546085

The finding that the lower mass brown dwarf in this system is hotter than its higher mass companion represents a challenge to brown dwarf evolutionary models, none of which predict this behavior. Here we present updated determinations of the basic physical properties of 2M0535-05, bolstering the surprising reversal of temperatures with mass in this system.

We compare these measurements with widely used brown dwarf evolutionary tracks, and find that the temperature reversal can be explained by some models if the components of 2M0535-05 are mildly non-coeval, possibly consistent with dynamical simulations of brown dwarf formation. Alternatively, a strong magnetic field on the higher mass brown dwarf might explain its anomalously low surface temperature, consistent with emerging evidence that convection is suppressed in magnetically active, low-mass stars.