Optical Images of an Exosolar Planet 25 Light Years from Earth

Authors: Paul Kalas (1), James R. Graham (1), Eugene Chiang (1,2), Michael P. Fitzgerald (3), Mark Clampin (4), Edwin S. Kite (2), Karl Stapelfeldt (5), Christian Marois (6), John Krist (5) ((1) Astronomy Department, University of California, Berkeley, CA, USA (2) Department of Earth & Planetary Science, University of California, Berkeley, CA, USA (3) Lawrence Livermore National Laboratory, Livermore, CA, USA (4) Goddard Space Flight Center, Greenbelt, MD, USA (5) Jet Propulsion Laboratory, Pasadena, CA, USA (6) Herzberg Institute for Astrophysics, Victoria, BC, Canada)

(Submitted on 13 Nov 2008)

Abstract: Fomalhaut is a bright star 7.7 parsecs (25 light years) from Earth that harbors a belt of cold dust with a structure consistent with gravitational sculpting by an orbiting planet.

Here, we present optical observations of an exoplanet candidate, Fomalhaut b. In the plane of the belt, Fomalhaut b lies approximately 119 astronomical units (AU) from the star, and within 18 AU of the dust belt. We detect counterclockwise orbital motion using Hubble Space Telescope observations separated by 1.73 years.

Dynamical models of the interaction between the planet and the belt indicate that the planet's mass is at most three times that of Jupiter for the belt to avoid gravitational disruption. The flux detected at 800 nm is also consistent with that of a planet with mass no greater than a few times that of Jupiter.

The brightness at 600 nm and the lack of detection at longer wavelengths suggest that the detected flux may include starlight reflected off a circumplanetary disk, with dimension comparable to the orbits of the Galilean satellites. We also observed variability of unknown origin at 600 nm.

Comments: 25 pages; 4 tables; 4 figures. To appear in Science November
13, 2008

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0811.1994v1 [astro-ph]

Submission history

From: James R. Graham [view email]

[v1] Thu, 13 Nov 2008 15:28:59 GMT (1709kb)

http://arxiv.org/abs/0811.1994