An Updated Visual Orbit of the Directly Imaged Exoplanet 51 Eridani b and Prospects for a Dynamical Mass Measurement with Gaia

Authors

• Robert J. De Rosa, Stanford University
• Eric L. Nielsen, Stanford University
• Jason J. Wang, California Institute of Technology
• S. Mark Ammons, Lawrence Livermore National Laboratory
• Gaspard Duchene, University of California, Berkeley
• Bruce MacIntosh, Stanford University
• Julien Rameau, Université Grenoble Alpes
• Vanessa P. Bailey, Jet Propulsion Laboratory
• Travis Barman, The University of Arizona
• Joanna Bulger, University Hawaii Institute for Astronomy
• Jeffrey Chilcote, University of Notre Dame
• Tara Cotten, University of Georgia
• Rene Doyon, Institut de Recherche sur les Exoplanètes
• Thomas M. Esposito, University of California, Berkeley
• Michael P. Fitzgerald, University of California, Los Angeles
• Katherine B. Follette, Amherst College
• Benjamin L. Gerard, University of Victoria
• Stephen J. Goodsell, Gemini Observatory
• James R. Graham, University of California, Berkeley
• Alexandra Z. Greenbaum, University of Michigan, Ann Arbor
• Pascale Hibon, Gemini ObservatorySouthern Operations Center
• Justin Hom, School of Earth and Space Exploration
• Li Wei Hung, US National Park Service
• Patrick Ingraham, Large Synoptic Survey Telescope
• Paul Kalas, University of California, Berkeley
• Quinn Konopacky, Center for Astrophysics & Space Sciences
• James E. Larkin, University of California, Los Angeles
• Jérôme Maire, Center for Astrophysics & Space Sciences
• Franck Marchis, SETI Institute
• Mark S. Marley, NASA Ames Research Center
• Christian Marois, University of Victoria
• Stanimir Metchev, Western University
• Kimberly Ward-Duong, Amherst CollegeFollow
• et al, Various Institutions

Document Type

Article

Publication Date

1-1-2020

Publication Title

Astronomical Journal

Abstract

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= 0.53-0.13+0.09) orbit at an intermediate inclination (i= 13611+10°), although circular orbits cannot be excluded due to the complex shape of the multidimensional posterior distribution. We find a semimajor axis of 11.1-1.3+4.2 au and a period of 28.1-4.9+17.2 yr, assuming a mass of 1.75 M· 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 2ω-3ω 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 MJup).

Volume

159

Issue

1

DOI

https://doi.org/10.3847/1538-3881/ab4da4

ISSN

00046256

Rights

© 2019. The Astronomical Society

Version

Version of Record

Recommended Citation

De Rosa, Robert J.; Nielsen, Eric L.; Wang, Jason J.; Ammons, S. Mark; Duchene, Gaspard; MacIntosh, Bruce; Rameau, Julien; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Esposito, Thomas M.; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hom, Justin; Hung, Li Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Metchev, Stanimir; Ward-Duong, Kimberly; and al, et, "An Updated Visual Orbit of the Directly Imaged Exoplanet 51 Eridani b and Prospects for a Dynamical Mass Measurement with Gaia" (2020). Astronomy: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ast_facpubs/115