Sun-like star gives up orbiting planet
17 Oct 2005 by Evoluted New Media
Astronomers have unveiled what they think is the first picture of a planet around a normal star similar to the Sun.
Astronomers have unveiled what they think is the first picture of a planet around a normal star similar to the Sun.
 |
| Image of star (termed 1RSX J160929.1-210524) and its likely planetary companion |
“This is the first time we have directly seen a planetary mass object in a likely orbit around a star like our Sun,” said David Lafrenière, lead author of a paper submitted to the Astrophysical Journal Letters. “If we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.”
They obtained spectra to confirm the nature of the companion, which has a mass about eight times that of Jupiter, and lies roughly 330 times the Earth-Sun distance away from its star. For comparison, the most distant planet in our solar system, Neptune, orbits the Sun at only about 30 times the Earth-Sun distance. The parent star is similar in mass to the Sun, but is much younger.
Team member Marten van Kerkwijk said: “We targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,” he said. “This is one reason we were able to see it at all.”
Until now, the only planet-like bodies that have been directly imaged outside of the solar system are either free-floating in space or orbit brown dwarfs, which are dim and make it easier to detect planetary-mass companions.
The existence of a planetary-mass companion so far from its parent star came as a surprise, and poses a challenge to theoretical models of star and planet formation. “This discovery is yet another reminder of the truly remarkable diversity of worlds out there, and it's a strong hint that nature may have more than one mechanism for producing planetary mass companions to normal stars,” said Ray Jayawardhana, team member.
