Our solar system may have plenty of cosmic cousins. Scientists studying archived data have spotted an adolescent sunlike star with a dusty belt that shows evidence of the creation and violent destruction of baby planets. “There is no doubt that they are detecting the dusty debris of rocky [Earth-like] planet formation,” says Scott Kenyon of the Harvard-Smithsonian Center for Astrophysics. A report of the find, by a team headed by Joseph Rhee of the University of California, Los Angeles, is in press at The Astrophysical Journal.
Until 2005, astronomers had observed only very young possible planet-forming systems. Then data from the retired Infrared Astronomy Satellite revealed a more mature system, bolstering predictions that collisions continue well after planets form. The latest observation, from a star called HD 23514 in the Pleiades cluster, should “help generalize the model of planetary formation,” says David Trilling of the University of Arizona in Tucson. Combined, the two discoveries allowed the team to estimate that about 1 in 1000 stellar systems share our system’s turbulent past–and could share its present architecture.
First published in Science Magazine as a Random Sample: [html] [pdf].
NASA’s Cassini mission celebrated its tenth year last week by releasing images of the solar system’s preening beauty, Saturn, and its fawning entourage of moons and rings. Eagle-eyed researchers spotted “moonlets” plowing through the delicate rings and reported the results in this week’s issue of Nature.
The moonlets measure just 30 to 70 meters across, but most of the debris in the rings measures less than 10 meters, so the moonlets leave a traceable wake. Saturn’s rings vary in thickness from about 100 meters to slightly more than 1 km.
In the image, Epimetheus (116 km across) floats just above Titan (5150 km), the largest of Saturn’s moons. The light-colored streaks in the ring may be caused by moonlets. The dark-colored section in the middle of the ring is the 325-km-wide Encke gap, probably caused by a gravitational resonance.
Cassini has mapped 60% of Titan’s northern hemisphere, which is home to lakes, rivers, and seas of liquid methane and ethane. The southern half is slated to be mapped next.
Originally appeared in Science Magazine as a Random Sample: [html] [pdf]