Atom & Cosmos

Straight from the stellar heart
Astronomers studying elderly stars called red giants have discovered acoustic oscillations that travel all the way to the hearts of the stars, providing a new tool to study the deep interiors of these bodies. An international team of scientists made the discovery by analyzing data on red giants recorded with NASA’s orbiting Kepler telescope. In contrast to most stellar vibrations, which travel only through a star’s outer layers, these waves showed a pattern indicating they had passed through the center. The new probe may reveal what the sun will look like in 5 billion years when it becomes a red giant, the researchers report online March 17 in Science. —Ron Cowen

April showers on Titan
A cold spring rain of methane may recently have fallen on the arid equator of Saturn’s moon Titan. Researchers base their deduction on images taken with the Cassini spacecraft, showing that the surface near Titan’s equator darkened after a cloud outburst. A large methane storm is the most likely explanation for the darkening, a team of U.S. planetary scientists says. The finding suggests that the dry channels observed at Titan’s low latitudes were carved recently by seasonal rains of methane and other hydrocarbons instead of during an earlier time when the equatorial region may have had a wetter climate, the team reports in the March 18 Science. —Ron Cowen

Old galaxies from young cosmos
An international team of astronomers has discovered a full-grown galaxy with old stars from an era just a billion years after the Big Bang. If such galaxies were common in the infant cosmos, they could challenge the notion that galaxies are built up little by little over time. The team reports the discovery in a paper posted online February 28 at arXiv.org. In another potential challenge to prevailing theory, a second international team reports in the February Astronomy & Astrophysics the discovery of the oldest mature cluster of galaxies known, from an era when the universe was just 3 billion years old. —Ron Cowen

Martian atmosphere lost to rocks
The composition of buried Martian rocks is providing new evidence that ancient Mars had a thick, carbon dioxide–rich atmosphere that enabled liquid water to be stable on the planet’s surface. The study also offers an explanation for how that atmosphere was lost. The buried rocks, exhumed by crater-blasting impacts, contain carbonate minerals that could have been deposited only if a large body of water reacted with an atmosphere abundant in carbon dioxide. If such carbonate storehouses are widespread, it would suggest that rocks depleted the Martian atmosphere, James Wray of Cornell University reported March 8 at the annual Lunar and Planetary Science Conference in The Woodlands, Texas. —Ron Cowen

Rare Earths
Earthlike planets are relatively scarce, with no more than 2.7 percent of sunlike stars possessing such orbs, a new study suggests. Researchers base their analysis on the first four months of observations recorded by the Kepler space telescope, which monitors some 150,000 stars for signs of passing planets. Astronomers at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., describe the findings in a paper posted March 9 at arXiv.org. —Ron Cowen