Artist’s concept of the star Fomalhaut and the Jupiter-type planet that the Hubble Space Telescope observed. A ring of debris appears to surround Fomalhaut as well. The planet, called Fomalhaut b, orbits the 200-million-year-old star every 872 years. Credit: ESA, NASA, and L. Calcada (ESO for STScI)
Estimated to be no more than three times Jupiter’s mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Australis, or the “Southern Fish.”
The planet is brighter than expected for an object of three Jupiter masses. One possibility is that it has a Saturn-like ring of ice and dust reflecting starlight. The ring might eventually coalesce to form moons. The ring’s estimated size is comparable to the region around Jupiter and its four largest orbiting satellites.
Future observations will attempt to see the planet in infrared light and will look for evidence of water vapor clouds in the atmosphere. This would yield clues to the evolution of a comparatively newborn 100-million-year-old planet. Astrometric measurements of the planet’s orbit will provide enough precision to yield an accurate mass.