Publication Date:
2013-02-28
Description:
This paper presents new observations of the planet-hosting, visual binary GJ 86 (HR 637) using the Hubble Space Telescope . Ultraviolet and optical imaging with WFC3 confirms the stellar companion is a degenerate star and indicates the binary semimajor axis is larger than previous estimates, with a 28 au. Optical STIS spectroscopy of the secondary reveals a helium-rich white dwarf with C 2 absorption bands and T eff = 8180 K, thus making the binary system rather similar to Procyon. Based on the 10.8 pc distance, the companion has 0.59 M and descended from a main-sequence A star of 1.9 M with an original orbital separation a 14 au. If the giant planet is coplanar with the binary, the mass of GJ 86Ab is between 4.4 and 4.7 M Jup . The similarity of GJ 86 and Procyon prompted a re-analysis of the white dwarf in the latter system, with the tentative conclusion that Procyon hosts a planetesimal population. The periastron distance in Procyon is 20 per cent smaller than in α Cen AB, but the metal-enriched atmosphere of Procyon B indicates that the planet formation process minimally attained 25 km bodies, if not small planets as in α Cen.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
