Friday, November 14, 2008

First Exoplanet Pictures?

It seems like just yesterday that we had no evidence of planets outside of our solar system. Now after many such planets have been found, the race is to get the first image of one. This may be it.

"Today, two teams of astronomers announced new exoplanet images, and in each case, I think they have the real deal. Only time and future observations will let us know for certain, but these objects have the look and feel of bona fide planets. One group found a planet orbiting Fomalhaut, the 18th brightest star in the night sky, and one of the Sun’s nearest stellar neighbors. The other team appears to have imaged three planets around a more obscure star known as HR 8799."

There is some great astronomy in there, my favorite being the debate over the dividing line between low-mass brown dwarves and high-mass planets, which may apply to one of these cases:

"...there is still no universally accepted definition of what distinguishes a high-mass planet from a low-mass brown dwarf. According to some astronomers, the line should be drawn at about 13 Jupiter masses — the mass at which a gaseous body can briefly fuse deuterium atoms in its core. According to that definition, Fomalhaut b is clearly a planet.

But other astronomers think the distinction should be based on formation. If a 3-Jupiter-mass object formed like a star from a collapsing gas cloud, it’s a very-low-mass brown dwarf. If it formed inside a disk, then it’s a planet. Since it’s unclear how Fomalhaut b formed, one could argue either way."

It's a pity more people don't understand how arbitrary a lot of astronomical terms are. If they did, they wouldn't have responded to some of the anti-science snarking that went on when Pluto's status was changed. That irony was knee deep: a moment forced upon us by substantial scientific progress portrayed as a sign of scientific impotence. Let's hope the same thing does not happen with the exoplanetary discoveries.

No comments: