Probable Rogue Planet Spotted 155
Maow writes with news of a sighting of a rogue gas giant: "'This object was discovered during a scan that covered the equivalent of 1,000 times the [area] of the full moon,' said study co-author Etienne Artigau of the University of Montreal. 'We observed hundreds of millions of stars and planets, but we only found one homeless planet in our neighborhood.' This planet appears to be an astonishingly young 50-120 million years old. The original paper is on the arXiv. Here's hoping the Mayan End-of-World-2012 people don't seize upon this as some kind of impending rogue planet on a collision course with Earth, but one can expect it'll be bantered about on such forums."
From the article: "The team believe it has a temperature of about 400C and a mass between four and seven times that of Jupiter - well short of the mass limit that would make it a likely brown dwarf."
How's that? (Score:5, Interesting)
Given that the definition of a planet is dependent on the relationship between objects (planet and star, planet and moon, planet and other objects in the same orbit), how can something be classified as a type of planet if there are no observations of that object in relation to other objects in a planetary system?
Re:How's that? (Score:4, Interesting)
And how do you determine the age of some random rocky mass that you can't even image?
Cause of ejection? (Score:2, Interesting)
Of the two possible origins of planets like this, the first would be that it's a star that didn't get enough mass to ignite. This seems to make the most intuitive sense to me.
The other possibility is that it was somehow ejected form it's parent star. This seems less likely, but then I'm not an astrophysicist. What would it take to eject a planet that large from it's solar system?
What kind of event would it take to say, eject Jupiter? Would it take a huge rogue Nemesis kind of star, or could something smaller perturb it's orbit just enough to eject it?
Assuming it was ejected, could you not interpolate from the planets velocity just where it came from, work backwards to find it's old parent star, and perhaps even figure out what other stellar body it interacted with that caused the planet to be ejected?