Optical Images of an Exosolar Planet 25 Light-Years from Earth

Abstract

Fomalhaut, a bright star 7.7 parsecs (25 light-years) from Earth, 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. Fomalhaut b lies about 119 astronomical units (AU) from the star and 18 AU of the dust belt, matching predictions of its location. Hubble Space Telescope observations separated by 1.73 years reveal counterclockwise orbital motion. 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; a higher mass would lead to gravitational disruption of the belt, matching predictions of its location. The flux detected at 0.8 mum is also consistent with that of a planet with mass no greater than a few times that of Jupiter. The brightness at 0.6 mum 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 observe variability of unknown origin at 0.6 mum.

Constraints on the gas content of the Fomalhaut debris belt

“…Quillen 2006). A candidate planetary body (Fomalhaut b) was detected (Kalas et al 2008), but subsequent observations showed that its orbit is highly eccentric (e = 0.8 ± 0.1), making it unlikely to be responsible for the observed morphology (Kalas et al 2013;Beust et al 2014;Tamayo 2014). There remains the possibility that a different, hereto unseen planet is shaping the belt; infrared surveys were only able to exclude planets with masses larger than a Jupiter mass (Kalas et al 2008;Marengo et al 2009;Janson et al 2012Janson et al , 2015.…”

Direct imaging and spectroscopy of planets and brown dwarfs in wide orbits

“…The cold-start models, never reaching temperature above 700 K, even for the youngest ages. (Lagrange et al 2009(Lagrange et al , 2010 and Fomalhaut b (Kalas et al 2008), respectively. The small black circles indicate planets found by the radial velocity and microlensing techniques from the Extrasolar Planets Encyclopaedia (http://exoplanet.eu/).…”

The truth about exoplanets

“…7), and a single planet more than 100 million years old orbiting Fomalhaut (ref. 8), a bright star some 8 parsecs from Earth.…”