An Updated Visual Orbit of the Directly Imaged Exoplanet 51 Eridani b and Prospects for a Dynamical Mass Measurement with Gaia
- Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)
- Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
- Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
- Univ. Grenoble Alpes/CNRS, IPAG, F-38000 Grenoble (France)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
- Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
- Department of Physics and Astronomy, University of Georgia, Athens, GA 30602 (United States)
- Institut de Recherche sur les Exoplanètes, Département de Physique, Université de Montréal, Montréal, QC, H3C 3J7 (Canada)
- Department of Physics & Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Physics and Astronomy Department, Amherst College, 21 Merrill Science Drive, Amherst, MA 01002 (United States)
- University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2 (Canada)
- Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720 (United States)
We present a revision to the visual orbit of the young, directly imaged exoplanet 51 Eridani b using four years of observations with the Gemini Planet Imager. The relative astrometry is consistent with an eccentric (e=0.53{sub -0.13}{sup +0.09}) orbit at an intermediate inclination (i=136{sub -11}{sup +10} °), although circular orbits cannot be excluded due to the complex shape of the multidimensional posterior distribution. We find a semimajor axis of 11.1{sub -1.3}{sup +4.2} au and a period of 28.1{sub -4.9}{sup +17.2} yr, assuming a mass of 1.75 M{sub ⊙} for the host star. We find consistent values with a recent analysis of VLT/SPHERE data covering a similar baseline. We investigate the potential of using the absolute astrometry of the host star to obtain a dynamical mass constraint for the planet. The astrometric acceleration of 51 Eri derived from a comparison of the Hipparcos and Gaia catalogs was found to be inconsistent at the 2σ–3σ level with the predicted reflex motion induced by the orbiting planet. Potential sources of this inconsistency include a combination of random and systematic errors between the two astrometric catalogs and the signature of an additional companion within the system interior to current detection limits. We also explored the potential of using Gaia astrometry alone for a dynamical mass measurement of the planet by simulating Gaia measurements of the motion of the photocenter of the system over the course of the extended 8 yr mission. We find that such a measurement is only possible (>98% probability) given the most optimistic predictions for the Gaia scan astrometric uncertainties for bright stars and a high mass for the planet (≳3.6 M {sub Jup}).
- OSTI ID:
- 23013119
- Journal Information:
- The Astronomical Journal (Online), Vol. 159, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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