[ichabodcole]

Would anyone like to explain why this planet would have a temperature of 400C (I was picturing it being really cold)? Is this because of its mass/size, more related to its gaseous composition or both?

[rpm4321]

It's a brown dwarf: http://en.wikipedia.org/wiki/CFBDSIR2149-0403

[wcoenen]

I think that the news here is that is has been determined that it is not a brown dwarf. See the paper[1] for more details. Though I'm not sure why the distinction between giant planet vs cold tiny star is so important.

[1] http://arxiv.org/abs/1210.0305

[scottscanlon]

ah, thanks for that.

[schiffern]

Compressive heating when gas collapsed into the planet.