Hubble's First Exoplanet
Researchers using the Hubble Space Telescope have taken the first image in visible light of a planet orbiting another star. The star is nearby, first magnitude Fomalhaut, which lies at a distance of 25 light years from Earth in the southern constellation of Piscis Austrinus.
The planet is designated Fomalhaut b, has a mass similar to that of Jupiter and orbits its star at a distance equal to four times the distance between our Sun and Neptune.
The planet had long been suspected to exist since a previous set of Hubble images in 2005 showed evidence for a ring of dust around Fomalhaut.
Paul Kalas of the University of California, Berkeley said, “The gravity of Fomalhaut b is the key reason that the vast dust belt surrounding Fomalhaut is cleanly sculpted into a ring and offset from the star. We predicted this in 2005, and now we have the direct proof."
Co-worker, James R. Graham agrees, "It will be hard to argue that a Jupiter-mass object orbiting an A star like Fomalhaut is anything other than a planet."
Their discovery is reported in today’s Science Express, and will be complemented by a further article in The Astrophysical Journal (ApJ).
The planet’s relatively low mass and huge orbit of the planet means that it cannot be detected by the more well-used method of planet detection – the ‘wobble’ that a planet induces in its parent star.
Fomalhaut is around 200 million years old and will survive another billion years, making it a short-lived star compared to our Sun, which is now about halfway through its 10 billion year lifetime.
Fomalhaut, as a first magnitude star, is extremely bright, so FT users are reminded not to image such a bright object.
Read the Science Express Article here
