Beta Pictoris, an A5 dwarf star some 63 light years from the Earth, is well known to exoplanet hunters, some of whom have been studying its circumstellar dust disk since its discovery by the Infrared Astronomical Satellite (IRAS). That disk was first detected way back in 1983, and is thought to be perhaps 1100 AU wide and much more massive than the disk from which our own Solar System formed. The disk and possible planetary formation going on there has always been tantalizingly like our own system's, but now we get a surprise. For as a new paper in Nature suggests, this young system (between eight and twenty million years old) contains much more carbon gas than expected. This work comes courtesy of the Far Ultraviolet Spectroscopic Explorer satellite (FUSE), along with Hubble's imaging spectrograph. The presence of carbon may solve at least one Beta Pictoris mystery: why didn't the star's radiation reduce the gas orbiting it? A hidden mass of hydrogen had been suspected as blocking...

It's shaping up to be a good week for exoplanet findings, with yesterday's intriguing work on 'planemos' and their disks and now, also presented at the AAS Calgary meeting, word of new findings on planetary migration. This is a significant issue, because so many of the exoplanets we know about are huge 'hot Jupiters' in tight orbits around their star. The effects such planets would have on smaller worlds in the habitable zone could be devastating if the gas giants migrated through that region early in the system's life. And migration is assumed to be what happens. The assumption is that such planets form a long way from their stars, as much as 20 AU out, and move to their present positions as the planet interacts tidally with the surrounding gas disk. But migration is tricky business, implying that most planets would fall into their stars within a million years. Preserving a solar system with gas giants and low-mass terrestrial worlds becomes challenging business (and recall that it...

Centauri Dreams marvels at the growth of the new lexicon whose definitions routintely fill these pages. Just the other day we encountered 'mascon' -- a concentration of mass denoting the presence of a long-obscured crater. Today we get 'planemos' -- planetary mass objects that float freely through space rather than orbiting a star. The latter come from new findings being discussed at the American Astronomical Society's Calgary meeting that started yesterday and runs through Thursday. We'll have a good deal to say about that meeting as the week progresses. But back to planemos, whose existence was suggested by earlier work on brown dwarfs, many of which are known to be surrounded by potentiallly planet-forming disks of material. "Now that we know of these planetary mass objects with their own little infant planetary systems, the definition of the word 'planet' has blurred even more," says Ray Jayawardhana (University of Toronto), who presented the findings in Calgary today. "In a way,...