Optical Images of an Exosolar Planet 25 Light Years from Earth

TL;DR

This paper reports optical observations of the exoplanet candidate Fomalhaut b, confirming its orbit, estimating its mass, and suggesting the presence of a circumplanetary disk, providing insights into planet-belt interactions.

Contribution

First optical detection and orbital confirmation of Fomalhaut b, with mass estimates and evidence of a circumplanetary disk, advancing understanding of exoplanetary systems.

Findings

Fomalhaut b orbits at about 119 AU from its star.

Mass of Fomalhaut b is at most a few times Jupiter's.

Detected flux suggests a circumplanetary disk.

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 18 AU from the belt, matching predictions. 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.