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Journal Articles The Astronomical Journal Year : 2020

The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet β Pictoris b from Combined Direct Imaging and Astrometry

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Eric L. Nielsen
  • Function : Author
Robert J. de Rosa
  • Function : Author
Jason J. Wang
  • Function : Author
Johannes Sahlmann
  • Function : Author
Paul Kalas
  • Function : Author
Mark S. Marley
  • Function : Author
Didier Saumon
  • Function : Author
Bruce Macintosh
  • Function : Author
Maxwell A. Millar-Blanchaer
  • Function : Author
Meiji M. Nguyen
  • Function : Author
S. Mark Ammons
  • Function : Author
Vanessa P. Bailey
  • Function : Author
Travis Barman
  • Function : Author
Joanna Bulger
  • Function : Author
Jeffrey Chilcote
  • Function : Author
Tara Cotten
  • Function : Author
Rene Doyon
  • Function : Author
Thomas M. Esposito
  • Function : Author
Michael P. Fitzgerald
  • Function : Author
Katherine B. Follette
  • Function : Author
Benjamin L. Gerard
  • Function : Author
Stephen J. Goodsell
  • Function : Author
James R. Graham
  • Function : Author
Alexandra Z. Greenbaum
  • Function : Author
Pascale Hibon
  • Function : Author
Li-Wei Hung
  • Function : Author
Patrick Ingraham
  • Function : Author
Quinn Konopacky
  • Function : Author
James E. Larkin
  • Function : Author
Jérôme Maire
  • Function : Author
Franck Marchis
  • Function : Author
Christian Marois
  • Function : Author
Stanimir Metchev
  • Function : Author
Rebecca Oppenheimer
  • Function : Author
David Palmer
  • Function : Author
Jennifer Patience
  • Function : Author
Marshall Perrin
  • Function : Author
Lisa Poyneer
  • Function : Author
Laurent Pueyo
  • Function : Author
Abhijith Rajan
  • Function : Author
Fredrik T. Rantakyrö
  • Function : Author
Jean-Baptiste Ruffio
  • Function : Author
Dmitry Savransky
  • Function : Author
Adam C. Schneider
  • Function : Author
Anand Sivaramakrishnan
  • Function : Author
Inseok Song
  • Function : Author
Remi Soummer
  • Function : Author
Sandrine Thomas
  • Function : Author
J. Kent Wallace
  • Function : Author
Kimberly Ward-Duong
  • Function : Author
Sloane Wiktorowicz
  • Function : Author
Schuyler Wolff
  • Function : Author

Abstract

We present new observations of the planet β Pictoris b from 2018 with the Gemini Planet Imager (GPI), the first GPI observations following conjunction. Based on these new measurements, we perform a joint orbit fit to the available relative astrometry from ground-based imaging, the Hipparcos Intermediate Astrometric Data (IAD), and the Gaia DR2 position, and demonstrate how to incorporate the IAD into direct imaging orbit fits. We find a mass consistent with predictions of hot-start evolutionary models and previous works following similar methods, though with larger uncertainties: 12.8+5.3-3.2 MJup. Our eccentricity determination of ${0.12}_{-0.03}^{+0.04}$ disfavors circular orbits. We consider orbit fits to several different imaging data sets, and find generally similar posteriors on the mass for each combination of imaging data. Our analysis underscores the importance of performing joint fits to the absolute and relative astrometry simultaneously, given the strong covariance between orbital elements. Time of conjunction is well-constrained within 2.8 days of 2017 September 13, with the star behind the planet's Hill sphere between 2017 April 11 and 2018 February 16 (±18 days). Following the recent radial velocity detection of a second planet in the system, β Pic c, we perform additional two-planet fits combining relative astrometry, absolute astrometry, and stellar radial velocities. These joint fits find a significantly smaller mass (8.0 ± 2.6 MJup) for the imaged planet β Pic b, in a somewhat more circular orbit. We expect future ground-based observations to further constrain the visual orbit and mass of the planet in advance of the release of Gaia DR4.

Dates and versions

insu-03705224 , version 1 (27-06-2022)

Identifiers

Cite

Eric L. Nielsen, Robert J. de Rosa, Jason J. Wang, Johannes Sahlmann, Paul Kalas, et al.. The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet β Pictoris b from Combined Direct Imaging and Astrometry. The Astronomical Journal, 2020, 159, ⟨10.3847/1538-3881/ab5b92⟩. ⟨insu-03705224⟩
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