Atom & Cosmos

Cloudy planets Some extrasolar planets heavier than about two Jupiters may have much thicker, cloudier atmospheres than predicted. Accounting for those cloudier atmospheres may alter the estimated masses of extrasolar planets. Thayne Currie of NASA’s Goddard Space Flight Center in Greenbelt, Md., and his colleagues base their findings on the unusually red colors of three of the four planets orbiting the star HR 8799. Thick clouds of silica or iron can account for the red colors, the team reports in a study posted online at arXiv.org on February 28. — Ron Cowen Hidden planets make tracks An unseen planet is the most likely culprit behind several features, including two rings and a gap, discovered in the planet-forming disk of material surrounding the young star AB Aurigae. The features all lie relatively far from the star — at Pluto’s average distance from the sun or greater—and may provide insight about the birth of recently imaged planets orbiting other stars at similar distances, an international team reports in the March 10 Astrophysical Journal Letters . In a study posted online at arXiv.org on March 3, another international team finds that gaps in the disks surrounding 12 other young stars may be to due to massive, unseen planets. — Ron Cowen Solar siblings Searching for the sun’s siblings — stars born 4.56 billion years ago in the same cluster as the sun — is fruitless if the cluster contained 1,000 stars or less. New simulations reveal that the siblings would have been gravitationally scattered so thoroughly across the Milky Way that none would be found today within 326 light-years of the sun. If the sun’s birth cluster contained 10,000 or more stars, however, a few of the kin may still lie within that distance, Russian astronomers report in an upcoming Monthly Notices of the Royal Astronomical Society . Finding members of the sun’s cluster could provide key information about the galaxy’s early history. — Ron Cowen Bountiful buckyballs Buckyballs, the soccer-ball-shaped cages of carbon atoms, may be more common in space than previously thought. The finding suggests a new mechanism for their origin. Previous laboratory experiments had suggested that buckyballs would primarily reside in rare, hydrogen-poor environments in space. But astronomer David Lambert of the University of Texas at Austin and his colleagues found just the opposite. Among a group of carbon-rich stars, most of which lack hydrogen, only two that had relatively substantial amounts of the light element appeared to harbor buckyballs. The molecules are therefore likely to be found in hydrogen-rich regions, the team concludes in the March 10 Astrophysical Journal . Such regions are plentiful in space. — Ron Cowen