A wide planetary-mass companion to a young M3 star of the AB Dor moving group

Département de physique and Observatoire du Mont-Mégantic, Université de Montréal, Montréal, QC H3C 3J7, Canada

^a e-mail: naud@asto.umontreal.ca

Abstract

We present a planetary-mass companion found 42′′ (2000 AU) from a M3 star, candidate member of the young (50-120 Myr) AB Doradus moving group. It was identified through an ongoing survey with GMOS at Gemini-South, via its distinctively red i-z color (>3.51). The comoving status of this object was confirmed by 2 epochs of WIRCam/CFHT J-band images. The NIR photometry and WISE colors suggest an early-to-mid T bound companion. A NIR spectrum, taken with GNIRS at Gemini-North, confirms a mid-T spectral type. With an estimated temperature between 900 K and 1200 K, models predict a mass between 7 and 12 M_Jup for this object. The benchmark character of this planetary-mass object lies in its relatively well-constrained age and in its very wide separation, that allows in-depth studies that can help validating models and understanding similar but closer-in companions such as the ones that will be uncovered by next-generation planet finders (e.g. GPI and SPHERE).