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."
Re:How's that? (Score:5, Informative)
Exoplanets use a different set of definitions according to the IAU [wikipedia.org]
may or may not be the first (Score:4, Informative)
For details we turn to our usual correspondent [wikipedia.org]...
Re:How's that? (Score:5, Informative)
And how do you determine the age of some random rocky mass that you can't even image?
According to the BBC article, they simply guessed the age. The sub-brown dwarf or rogue planet seems to be travelling with a group of stars, and they've estimated the age of the stars to be 50 - 120 million years. It's a form of extra-solar profiling: That thing over there isn't a star, but it's hanging out with those other stars, so it must the same age as them. (Which is apparently OK to do for stars, but not people?)
Re:How's that? (Score:5, Informative)
Re:How's that? (Score:5, Informative)
Based on a quick scan of the paper, it looks like they did a spectral and photometry analysis based on it's estimated size, compared it to their atmospheric models, and determined a probable age. They did image it, BTW, just not very clearly since it is pretty far away (sticks out like a proverbial sore thumb on infrared, thanks to it's warmth). They also matched that to probable origins based on it's path and determined a likely group to which it belongs, which helps confirm the age slightly. Note that this estimate is rather tentative, since it's hard to say exactly.
Re:Maybe their eagles (Score:5, Informative)
You should have at least capitalized Eagles to give people a better hint that you were referring to Space: 1999. The way you did it was just kinda cruel to younger geeks and SF nerds.
Re:Maybe their eagles (Score:5, Informative)
Poorly executed name-drop of Space:1999 [wikipedia.org]
Re:Why hope? (Score:5, Informative)
A Black Dwarf [wikipedia.org] is not actually a gas giant which was never a star, but rather the end point of evolution of a white dwarf (which is itself the post-fusion remnant of main sequence stars like the sun), when it cools off and is no longer emitting significant amounts of light (even in infrared). None of these are thought to exist because it's going to take much longer than the current age of the universe (as in 10,000 times the current age of the universe or more) for the white dwarfs to cool off to that degree.
A Brown Dwarf [wikipedia.org] is a sub-stellar object, i.e. something that was never a star undergoing sustained fusion, and while the larger ones would be expected to glow in the low visible range (red), and of course infrared, the smaller ones at around 500K may not glow in visible light at all yet are still classified as brown dwarfs instead of planets. The boundary is a little fuzzy. In any case, though, they'd never appear "brown" from their emitted light.
Dwarf terminology is weird.