—Extrasolar Planets Imaged

Two groups have produced the first direct images of planets orbiting other stars:

First-ever images taken of extrasolar planets – Space.com- msnbc.com

One is a sort of spooky infrared image from the Hubble ACS of the relatively nearby star Fomalhaut.  Images were taken 4 years apart to verify that the object is actually in orbit around Fomalhaut.  The object appears to be “herding” the outer portion of Fomalhaut’s accretion disc into a distinct, bright edge.

The other set of images is of several planetary object in orbit around HR 8799.  These were apparently imaged in visible light by ground-based telescopes on Mauna Kea in Hawaii. 

The technology for planet detection is improving dramatically.  Of course, when the excitement dies down a bit, astronomers will go back to squabbling about the definition of “planet”.  The smallest of these objects, now labeled Fomalhaut B, is three times the mass of Jupiter.  Several of the others are estimated to be around 10 times Jupiter’s mass.  Somewhere around 13xJupiter is apparently the lower limit for a type of failed star called a “Brown Dwarf”.  As techniques improve, it should become possible to resolve planets of  a more practical size.


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