Detection of strong activity in the eclipsing binary brown dwarf 2MASSJ05352184-0546085 - A possible explanation for the temperature reversal

TL;DR

This study analyzes high-resolution spectra of the eclipsing brown dwarf binary 2MASSJ05352184-0546085, confirming a temperature reversal likely caused by magnetic activity inhibiting convection, with the primary showing stronger Halpha emission and faster rotation.

Contribution

It provides the first detailed spectral analysis confirming the temperature reversal and links it to magnetic activity and rotation differences in the binary system.

Findings

Temperature reversal confirmed through spectral comparison.

Primary exhibits at least twice the rotation speed of the secondary.

Halpha emission from the primary is at least 7 times stronger.

Abstract

We show high resolution spectra of the eclipsing brown dwarf binary 2MASSJ05352184-0546085 taken at the two opposite radial velocity maxima. Comparisons of the TiO bands to model and template spectra are fully consistent with the temperatures previously derived for this system. In particular, the reversal of temperatures with mass - in which the higher-mass primary is cooler than its companion - is confirmed. We measure the projected rotation velocities of the compononents; the primary is rotating at least twice as rapidly as the secondary. At the two radial velocity maxima, Halpha emission lines of both components stick out to either sides of the Halpha central wavelength, which is dominated by nebula emission. This enables us to model the individual Halpha lines of the primary and the secondary. We find that the Halpha emission from the primary is at least 7 times stronger than the emission from the secondary. We conclude that the temperature reversal is very likely due to strong magnetic fields inhibiting convection on the primary.