The Hawaii Infrared Parallax Program. III. 2MASS J0249–0557 c: A Wide Planetary-mass Companion to a Low-mass Binary in the Pic Moving Group

Abstract

We have discovered a wide planetary-mass companion to the beta Pic moving group member 2MASS J02495639-0557352 (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, 2MASS J0249-0557ABc is a bound triple system with an 11.6(-1.0)(+1.3) M-Jup object separated by 1950 +/- 200 au (40 '') from a relatively close (2.17 +/- 0.22 au, 0.'' 04) pair of 48(-12)(+13) M(Jup )and 44(-11)(+14) M-Jup objects. 2MASS J0249-0557AB is one of the few ultracool binaries to be discovered in a young moving group and the first confirmed in the beta Pic moving group (22 +/- 6 Myr). The mass, absolute magnitudes, and spectral type of 2MASS J0249-0557 c (L2 VL G) are remarkably similar to those of the planet beta Pic b (L2, 13.0(-0.3)(+0.4)M(Jup)). We also find that the free-floating object 2MASS J2208+2921 (L3 VL-G) is another possible & nbsp;beta Pic moving group member with colors and absolute magnitudes similar to beta Pic b and 2MASS J0249-0557 c. beta Pic b 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.