Lowest Mass Exoplanet Ever Directly Imaged. Probably. 43
The Bad Astronomer writes "Astronomers announced today that they have taken a direct image of the lowest mass exoplanet ever seen. HD 95086 b has a mass about 4 to 5 times that of Jupiter, and orbits a star 300 light years away that is slightly more massive and hotter than the Sun. The planet is not 100% confirmed, but it appears very likely to be real. If so, it's a hot gas giant, still cooling from its formation less than 20 million years ago. The picture, taken in the infrared, clearly shows the planet, making it one of fewer than a dozen such planets seen in actual telescopic images."
Re:Why a hot gas planet? (Score:5, Informative)
I'm not an expert, so ignore me if one shows up; but my suspicion would be that they cool down enough that we can't see them anymore: You'd get a lot of heat, initially, when the planet coalesces; but if it isn't massive enough to ignite fusion and become a star, it'll just keep bleeding radiation into space until it reaches whatever equilibrium temperature the intensity and location of its local star provide for. As they get colder, their output gets weaker, until it gets to the point where our instruments are insufficiently sensitive to distinguish it from the background(unless it passes in front of its star, which has allowed us to indirectly infer the existence of smaller objects that we can't see directly).
Re:Lowest mass? (Score:4, Informative)
Directly observed - this planet has been imaged. Most of the confirmed planets from the Kepler mission are inferred from the dip in luminosity the parent star exhibits when the planet transitions across it, as viewed from Earth, or we can infer that there are planets/binary partner if a star "wobbles". Direct images of exo-planets are rare, even this one a mere 300 LY away is still only a tiny blip on the screen.
Re:Probably pretty cold (Score:4, Informative)
No need to be sad. Increasing effective aperture size of the telescope increases its resolving power. The imaging element doesn't have to be a single mirror or lens, but can consist of an array of elements scattered over a large area. Tricky part is getting all of the elements in phase agreement. Also doesn't have to be visible light. We are already 'imaging' surfaces of planets with synthetic aperture radar, operating on the same principle.
http://en.wikipedia.org/wiki/Very_Large_Telescope [wikipedia.org]
http://en.wikipedia.org/wiki/Very_Large_Array [wikipedia.org]
So imagine a much larger optical array network, many miles in diameter, for imaging the surfaces of these exoplanets.