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

摘要

Aims. We study the formation of substellar objects (exoplanets and brown dwarfs) that are companions to young nearby stars. Methods. With high-contrast AO imaging obtained with NACO at ESO VLT, we search for faint companion candidates around our targets, whose companionship can be confirmed with astrometry. Results. We identified a faint substellar companion to the nearby pre-main sequence star PZ?Tel, a member of the β?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) northeast of PZ?Tel. Within three NACO observing epochs, we can confirm the common proper motion (>39σ) and detected orbital motion of PZ?Tel?B around its primary (>37σ). The photometry of the newly found companion is consistent with a brown dwarf with a mass between?24 and 40MJup, 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 β?Pic?b, PZ?Tel?B is the second closest substellar companion imaged directly around a young star.