摘要：We have discovered a wide planetary-mass companion to the βPic moving group member 2MASSJ02495639 −0557352 (M6 VL-G) using Canada–France–Hawaii Telescope/WIRCam astrometry from the Hawaii Infrared Parallax Program. In addition, Keck laser guide star adaptive optics aperture-masking interferometry shows that the host is itself a tight binary. Altogether, 2MASSJ0249−0557ABc is a bound triple system with an 11.6 1.0 1.3 - + MJup object separated by 1950±200 au (40″) from a relatively close (2.17±0.22 au, 0 04) pair of 48 12 13 - + MJup and 44 11 14 - + MJupobjects. 2MASSJ0249−0557AB is one of the few ultracool binaries to be discovered in a young moving group and the first confirmed in the βPic moving group (22±6 Myr). The mass, absolute magnitudes, and spectral type of 2MASSJ0249−0557c (L2 VL-G) are remarkably similar to those of the planet βPicb (L2, 13.0 0.3 0.4 - + MJup). We also find that the free-floating object 2MASSJ2208+2921 (L3 VL-G) is another possible βPic moving group member with colors and absolute magnitudes similar to βPicb and 2MASSJ0249−0557c. βPicb is the first directly imaged planet to have a “twin,” namely an object of comparable properties in the same stellar association. Such directly imaged objects provide a unique opportunity to measure atmospheric composition, variability, and rotation across different pathways of assembling planetary-mass objects from the same natal material.
