2018/12/20 by Logan Pearce, Logan A. Pearce, Pearce, Logan A. +16 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astrometry #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Classical mechanics #Direct imaging #Earth and Planetary Astrophysics (astro-ph.EP) #Exoplanet #FOS: Physical sciences #Mean motion #Orbit (dynamics) #Orbital decay #Orbital eccentricity #Orbital elements #Orbital mechanics #Orbital motion #Physics #Planet #Planetary system #Proper motion #Satellite #Scattering #Stars #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.48550/arxiv.1812.08860
Accepted to AJ; 20 pages, 12 figures, 5 tables in two-column AASTEX6 format
arxiv created 2018/12/20 · openalex publication_date 2018/12/20 · arxiv updated 2018/12/24 · openalex created_date 2022/08/01 · openalex updated_date 2026/07/28
Direct-imaging exoplanet surveys have discovered a class of 5-20 Mjup space\nsubstellar companions at separations >100 AU from their host stars, which\npresent a challenge to planet and star formation models. Detailed analysis of\nthe orbital architecture of these systems can provide constraints on possible\nformation mechanisms, including the possibility they were dynamically ejected\nonto a wide orbit. We present astrometry for the wide planetary-mass companion\nGSC~6214-210 ,b (240 AU; \≈14 Mjup) obtained using NIRC2 with adaptive\noptics at the Keck telescope over ten years. Our measurements achieved\nastrometric uncertainties of \≈1 mas per epoch. We determined a relative\nmotion of 1.12 \± 0.15~mas~yr-1 (0.61 \± 0.09 km s-1), the\nfirst detection of orbital motion for this companion. We compute the minimum\nperiastron for the companion due to our measured velocity vector, and derive\nconstraints on orbital parameters through our modified implementation of the\nOrbits for the Impatient rejection sampling algorithm. We find that close\nperiastron orbits, which could indicate the companion was dynamically\nscattered, are present in our posterior but have low likelihoods. For all\norbits in our posterior, we assess the detectability of close-in companions\nthat could have scattered GSC~6214-210 ,b from a closer orbit, and find that\nmost potential scatterers would have been detected in previous imaging. We\nconclude that formation at small orbital separation and subsequent dynamical\nscattering through interaction with another potential close-in object is an\nunlikely formation pathway for this companion. We also update stellar and\nsubstellar properties for the system due to the new parallax from \Gaia\nDR2.\n