THE ORBIT AND TRANSIT PROSPECTS FOR β PICTORIS b CONSTRAINED WITH ONE MILLIARCSECOND ASTROMETRY
Year: 2016
Type: article
Abstract: ABSTRACT A principal scientific goal of the Gemini Planet Imager (GPI) is obtaining milliarcsecond astrometry to constrain exoplanet orbits. However, astrometry of directly imaged exoplanets is subject to biases, systematic errors, and speckle noise. Here, we describe an analytical procedure to forward model the signal of an exoplanet that accounts for both the observing strategy (angular and spectral differential imaging) and the data reduction method (Karhunen–Loève Image Projection algorithm). We use this forward model to measure the position of an exoplanet in a Bayesian framework employing Gaussian processes and Markov-chain Monte Carlo to account for correlated noise. In the case of GPI data on β Pic b, this technique, which we call Bayesian KLIP-FM Astrometry (BKA), outperforms previous techniques and yields 1σ errors at or below the one milliarcsecond level. We validate BKA by fitting a Keplerian orbit to 12 GPI observations along with previous astrometry from other instruments. The statistical properties of the residuals confirm that BKA is accurate and correctly estimates astrometric errors. Our constraints on the orbit of β Pic b firmly rule out the possibility of a transit of the planet at 10-σ significance. However, we confirm that the Hill sphere of β Pic b will transit, giving us a rare chance to probe the circumplanetary environment of a young, evolving exoplanet. We provide an ephemeris for photometric monitoring of the Hill sphere transit event, which will begin at the start of April in 2017 and finish at the end of January in 2018.
Source: The Astronomical Journal
Authors: Jason J. Wang, James R. Graham, Laurent Pueyo, Paul Kalas, Maxwell A. Millar-Blanchaer, Jean-Baptiste Ruffio, Robert J. De Rosa, S. Mark Ammons, Pauline Arriaga, Vanessa P. Bailey, Travis S. Barman, Joanna Bulger, Adam S. Burrows, Andrew Cardwell, Christine H. Chen, Jeffrey K. Chilcote, Tara Cotten, Michael P. Fitzgerald, Katherine B. Follette, René Doyon, Gaspard Duchêne, Alexandra Z. Greenbaum, Pascale Hibon, Li-Wei Hung, Patrick Ingraham, Quinn M. Konopacky, James E. Larkin, Bruce Macintosh, Jérôme Maire, Franck Marchis, Mark S. Marley, Christian Marois, Stanimir Metchev, Eric L. Nielsen, Rebecca Oppenheimer, David W. Palmer, Rahul Patel, Jenny Patience, Marshall D. Perrin, Lisa A. Poyneer, Abhijith Rajan, Julien Rameau, Fredrik T. Rantakyrö, Dmitry Savransky, Anand Sivaramakrishnan, Inseok Song, Remi Soummer, Sandrine Thomas, Gautam Vasisht, David Vega, J. Kent Wallace, Kimberly Ward-Duong, Sloane J. Wiktorowicz, Schuyler G. Wolff
Institutions: University of California, Berkeley, Space Telescope Science Institute, University of Toronto, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Lawrence Livermore National Laboratory, University of California, Los Angeles, University of Arizona, National Astronomical Observatory of Japan, Princeton University, International Gemini Observatory, University of Georgia, Université de Montréal, Centre National de la Recherche Scientifique, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Johns Hopkins University, European Southern Observatory, Large Synoptic Survey Telescope Corporation, University of California San Diego, Search for Extraterrestrial Intelligence, Ames Research Center, Herzberg Institute of Astrophysics, University of Victoria, National Research Council Canada, Western University, Stony Brook University, American Museum of Natural History, California Institute of Technology, Infrared Processing and Analysis Center, Arizona State University, Cornell University, Jet Propulsion Laboratory, The Aerospace Corporation
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2490708200