Star’s Dust May Hold Clue to New Planet

Is this a planet in the making?

A gap in the dust circling a young star in the constellation Auriga may mark where material is condensing into a planet, 11 astronomers led by Ben R. Oppenheimer of the American Museum of Natural History say in a paper to be published in The Astrophysical Journal.

The group used an Air Force surveillance telescope at Haleakala Observatories on the Hawaiian island of Maui and a special camera to examine a region near the star AB Aurigae, corresponding to the scale of our own solar system, that had not been observed before at high resolution. The results, they said, provided new insight into the process of planet and star formation.

The star is about 470 light years away and, being only about one million to three million years old, is still surrounded by the dusty detritus out of which it formed. In the picture, which shows the intensity of so-called polarized light scattered off dust particles, there is a gap about nine billion miles from the star, roughly three times the distance from Earth to Neptune.

Intriguingly, there is also what Dr. Oppenheimer and his colleagues call a “low significance detection” of a bright dot in the gap. If real, it could either be dust condensing on some object, Dr. Oppenheimer explained, or the object itself, which, based on its age and brightness would be 5 to 37 times the mass of Jupiter. That would put it on the dividing line between a planet and a kind of failed star called a brown dwarf.

“It does seem to be there,” Dr. Oppenheimer said in an interview.

Alan P. Boss, a planetary theorist at the Carnegie Institution of Washington, urged caution, noting that the astronomers “are trying something very difficult.” He said if the gap was real and something was forming there, it was more likely to be a brown dwarf, because it would be very hard to make that big a planet so far from its star.

“Either way,” Dr. Boss said in an e-mail message, “if it is real, it is another nice step along the way to direct imaging of planets in general and planets in formation in particular.”