Orbital and evolutionary constraints on the planet hosting binary GJ 86 from the Hubble Space Telescope
Abstract
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 C2 absorption bands and Teff = 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 MJup.
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.- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2013
- DOI:
- 10.1093/mnras/sts677
- arXiv:
- arXiv:1212.5601
- Bibcode:
- 2013MNRAS.430..652F
- Keywords:
-
- binaries: visual;
- stars: individual: GJ 86A;
- stars: individual: GJ 86B;
- planetary systems;
- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted to MNRAS, 9 pages, 6 figures, 5 tables