The Gemini Planet Imager Exoplanet Survey: Dynamical Mass of the Exoplanet β Pictoris b from Combined Direct Imaging and Astrometry
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- Stanford Univ., CA (United States)
- California Inst. of Technology (CalTech), Pasadena, CA (United States)
- Space Telescope Science Inst., Baltimore, MD (United States)
- Univ. of California, Berkeley, CA (United States); SETI Inst., Mountain View, CA (United States); Inst. of Astrophysics, Heraklion (Greece)
- Univ. of California, Berkeley, CA (United States); Univ. Grenoble Alpes (France)
- Univ. Grenoble Alpes (France); Univ. of Montreal, QC (Canada)
- NASA Ames Research Center (ARC), Mountain View, CA (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Univ. of California, Berkeley, CA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Arizona, Tucson, AZ (United States)
- Univ. of Hawaii, Honolulu, HI (United States); National Astronomical Observatory of Japan (NAOJ), Hilo, HI (United States)
- Univ. of Notre Dame, IN (United States)
- Univ. of Georgia, Athens, GA (United States)
- Univ. of Montreal, QC (Canada)
- Univ. of California, Los Angeles, CA (United States)
- Amherst College, MA (United States)
- Univ. of Victoria, BC (Canada); National Research Council of Canada Herzberg, Victoria, BC (Canada)
- Gemini Observatory, Hilo, HI (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Gemini Observatory, La Serena (Chile)
- National Park Service, Fort Collins, CO (United States)
- Large Synoptic Survey Telescope, Tucson, AZ (United States)
- Univ. of California San Diego, La Jolla, CA (United States)
- SETI Inst., Mountain View, CA (United States)
- Univ. of Western Ontario, London, ON (Canada); Stony Brook Univ., NY (United States)
- American Museum of Natural History (AMNH), New York, NY (United States)
- Arizona State Univ., Tempe, AZ (United States)
- Cornell Univ., Ithaca, NY (United States)
- Univ. of California, Santa Cruz, CA (United States)
- Leiden Univ. (Netherlands)
Herein, 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: $$12.8^{+5.3}_{–3.2} M_{Jup}$$. 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 M Jup) 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.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Fonds de Recherche du Québec; Heising-Simons Foundation; Ministerio da Ciencia, Tecnologia e Inovacao (MCTI); Ministerio de Ciencia, Tecnologia e Innovacion Productiva (MINCYT); National Aeronautics and Space Administration (NASA); National Research Council Canada (NRC); National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC)
- Grant/Contract Number:
- 89233218CNA000001; AC02-05CH11231; AC52-07NA27344
- OSTI ID:
- 1760570
- Report Number(s):
- LA-UR--19-31273
- Journal Information:
- The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 159; ISSN 1538-3881
- Publisher:
- IOP Publishing - AAASCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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