News Scan Briefs; March 2003; Scientific American Magazine; by George Musser, JR Minkel, Steve Mirsky, Charles Choi; 2 Page(s)
Has a Nice Ring to It: A fair number of the stars in the Milky Way are puzzlingly un-Milky Way-like. At the January meeting of the American Astronomical Society, Heidi Jo Newberg of the Rensselaer Polytechnic Institute, Brian Yanny of Fermilab and their colleagues described the largest batch of such anomalies yet. Detected by the Sloan Digital Sky Survey, the stars are packed more tightly, move slower (110 kilometers a second, half the usual speed) and contain fewer heavy elements than typical stars in the outer galaxy. They form an arc about 60,000 light-years from the galaxy's center, twice as far out as the sun. The arc may be part of a complete ring, with a total of 500 million or so stars. It could be the remains of a small galaxy that got ripped apart 10 billion years ago, but other researchers think it is actually a cast-off from the Milky Way itself. Rings and other coherent patterns are sensitive to the shape of the galaxy's gravitational field, so astronomers hope to use them to map the distribution of dark matter.-George Musser
Self-Organized Scenery: Various filigreed patterns of stone circles, polygons, stripes and labyrinths are seen in arctic soils, but researchers have never been able to account for the full panoply of shapes. Now Mark A. Kessler of the University of California at Santa Cruz and Brad Werner of the University of California at San Diego have used a computer model to determine that the rhythm of freeze-thaw cycles produces two main mechanisms that generate any stone pattern.