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The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au

  • Author(s): Nielsen, EL
  • De Rosa, RJ
  • Macintosh, B
  • Wang, JJ
  • Ruffio, JB
  • Chiang, E
  • Marley, MS
  • Saumon, D
  • Savransky, D
  • Mark Ammons, S
  • Bailey, VP
  • Barman, T
  • Blain, C
  • Bulger, J
  • Burrows, A
  • Chilcote, J
  • Cotten, T
  • Czekala, I
  • Doyon, R
  • Duchene, G
  • Esposito, TM
  • Fabrycky, D
  • Fitzgerald, MP
  • Follette, KB
  • Fortney, JJ
  • Gerard, BL
  • Goodsell, SJ
  • Graham, JR
  • Greenbaum, AZ
  • Hibon, P
  • Hinkley, S
  • Hirsch, LA
  • Hom, J
  • Hung, LW
  • Ilene Dawson, R
  • Ingraham, P
  • Kalas, P
  • Konopacky, Q
  • Larkin, JE
  • Lee, EJ
  • Lin, JW
  • Maire, J
  • Marchis, F
  • Marois, C
  • Metchev, S
  • Millar-Blanchaer, MA
  • Morzinski, KM
  • Oppenheimer, R
  • Palmer, D
  • Patience, J
  • Perrin, M
  • Poyneer, L
  • Pueyo, L
  • Rafikov, RR
  • Rajan, A
  • Rameau, J
  • Rantakyrö, FT
  • Ren, B
  • Schneider, AC
  • Sivaramakrishnan, A
  • Song, I
  • Soummer, R
  • Tallis, M
  • Thomas, S
  • Ward-Duong, K
  • Wolff, S
  • et al.

© 2019. The American Astronomical Society. All rights reserved.. We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M ∗ >1.5 M o more likely to host planets with masses between 2 and 13M Jup and semimajor axes of 3-100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semimajor axis (a) for planet populations around high-mass stars (M ∗ >1.5 M o) of the form , finding α = -2.4 +0.8 and β = -2.0 +0.5, and an integrated occurrence rate of % between 5-13M Jup and 10-100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with % of stars hosting a brown dwarf companion between 13-80M Jup and 10-100 au. Brown dwarfs also appear to be distributed differently in mass and semimajor axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semimajor axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the radial velocity method, our results are consistent with a peak in occurrence of giant planets between ∼1 and 10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability.

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