Discovery of a low-mass companion around HR3549

TL;DR

This paper reports the discovery of a low-mass companion, likely a brown dwarf, orbiting the star HR3549 beyond its warm debris disk, providing new insights into substellar companion formation.

Contribution

It presents the first direct imaging detection of a brown dwarf companion around HR3549 and discusses its implications for formation models.

Findings

Companion at ~80 AU separation confirmed by proper motion

Companion mass estimated between 15-80 M_J

Presence of warm debris disk alongside the brown dwarf

Abstract

We report the discovery of a low-mass companion to HR3549, an A0V star surrounded by a debris disk with a warm excess detected by WISE at 22 $\mu$m ($10\sigma$ significance). We imaged HR3549 B in the L-band with NAOS-CONICA, the adaptive optics infrared camera of the Very Large Telescope, in January 2013 and confirmed its common proper motion in January 2015. The companion is at a projected separation of $\simeq 80$ AU and position angle of $\simeq 157^\circ$, so it is orbiting well beyond the warm disk inner edge of $r > 10$ AU. Our age estimate for this system corresponds to a companion mass in the range 15-80 $M_J$, spanning the brown dwarf regime, and so HR3549 B is another recent addition to the growing list of brown dwarf desert objects with extreme mass ratios. The simultaneous presence of a warm disk and a brown dwarf around HR3549 provides interesting empirical constraints on models of the formation of substellar companions.