The change comes from the gravitational tug of the planet as it moves from one side of the star to the other. Its almost circular orbit suggests to astronomers that the planet formed in the same way as Earth and the other solar-system worlds. According to the most accepted theory, planets form from gas and dust left over from the birth of a sun. This material swirls around the sun in a disk billions of miles in diameter, the gas and particles attracting each other by gravity. Dust builds into rocks, small rocks into large rocks until, over millions of years, they coalesce into rocky planets like Earth, or huge gas balls like Jupiter.
Stars often form in pairs.
The bigger twin may attract enough material from the smaller to prevent gravity from squeezing the latter tightly enough to form a fiery globe of gas. In other words, some of the Jovian-size objects near stars may be cold, failed stars rather than planets. If so, that burns a hole in the theory that planets, and hence places where life could begin, are as common as some scientists believe, or hope. Timothy Brown and Edward Kennelly of the National Center for Atmospheric Research in Boulder, Colo., also participated in the discovery. The Harvard-Smithsonian team also included Sylvain Korzennik, Martin Krockenberger, and Peter Nisenson, researchers at the Harvard Center for Astrophysics, and Saurabh Jha, a Harvard graduate student in astronomy.