Direct detection of a substellar companion to the young nearby star PZ Telescopii

TL;DR

This paper reports the direct imaging and confirmation of a brown dwarf companion to the young star PZ Tel, demonstrating the detection of substellar objects around nearby stars using high contrast adaptive optics imaging.

Contribution

First direct imaging and astrometric confirmation of a brown dwarf companion to PZ Tel, showcasing a method for detecting substellar companions around young stars.

Findings

Confirmed common proper motion of PZ Tel B (>39 sigma)

Detected orbital motion (>37 sigma)

Estimated mass of 24-40 MJup and temperature of 2500-2700 K

Abstract

Aims: We study the formation of substellar objects (exoplanets and brown dwarfs) as companions to young nearby stars. Methods: With high contrast AO imaging obtained with NACO at ESO's VLT we search for faint companion-candidates around our targets, whose companionship can be confirmed with astrometry. Results: In the course of our imaging campaign we found a faint substellar companion of the nearby pre-main sequence star PZ Tel, a member of the beta Pic moving group. The companion is 5-6 mag fainter than its host star in JHK and is located at a separation of only 0.3 arcsec (or 15 AU of projected separation) north-east of PZ Tel. Within three NACO observing epochs we could confirm common proper motion (>39 sigma) and detected orbital motion of PZ Tel B around its primary (>37 sigma). The photometry of the newly found companion is consistent with a brown dwarf with a mass of 24 to 40 MJup, at the distance (50 pc) and age (8-20 Myr) of PZ Tel. The effective temperature of the companion, derived from its photometry, ranges between 2500 and 2700 K, which corresponds to a spectral type between M6 and M8. After beta Pic b, PZ Tel B is the second closest substellar companion imaged directly around a young star.