Discovery of an M9.5 Candidate Brown Dwarf in the TW Hydrae Association - DENIS J124514.1-442907

TL;DR

This paper reports the discovery of a candidate brown dwarf in the TW Hydrae Association, with spectral features indicating a very low mass and youth, but further measurements are needed to confirm its membership.

Contribution

It presents the identification and initial characterization of a new substellar object in the TW Hydrae Association, expanding the known population of young brown dwarfs.

Findings

Spectral type M9.5 indicating a very low mass (<24 M_Jup)

Spectral features consistent with youth and low surface gravity

Position coincident with TW Hydrae Association, pending confirmation

Abstract

We report the discovery of a fifth candidate substellar system in the ~5-10 Myr TW Hydrae Association - DENIS J124514.1-442907. This object has a NIR spectrum remarkably similar to that of 2MASS J1139511-315921, a known TW Hydrae brown dwarf, with low surface gravity features such as a triangular-shaped H-band, deep H2O absorption, weak alkali lines, and weak hydride bands. We find an optical spectral type of M9.5 and estimate a mass of <24 M_Jup, assuming an age of ~5-10 Myr. While the measured proper motion for DENIS J124514.1-442907 is inconclusive as a test for membership, its position in the sky is coincident with the TW Hydrae Association. A more accurate proper motion measurement, higher resolution spectroscopy for radial velocity, and a parallax measurement are needed to derive the true space motion and to confirm its membership.