SERVING THE ON-LINE RPI COMMUNITY SINCE 1994 SEARCH ARCHIVES Current Issue: Volume 130, Number 1 July 14, 2009 Features RPI physicist helps identify new stars Posted 01-16-2002 at 8:03PM Scott Robertson Senior Reporter Heidi Jo Newberg, associate professor of physics, and Brian Yanny, an astrophysicist at Fermi National Accelator Laboratory, have identified new star structures in the halo of the Milky Way Galaxy. Newberg and Yanny presented plots of color versus brightness for stars in two previously discovered, tidally disrupted structures at the American Astronomical Society’s recent meeting in Washington D.C. The distribution of stars in their plots, which could provide clues to metallicity and stellar age, are consistent with examinations of those in the Sagittarius dwarf galaxy, although the stars in their plots are 75 degrees away from the center of the Sagittarius dwarf and are spread across 110 square degrees of sky. Newberg and Yanny also identified five other overdensities of stars in the Milky Way Galactic halo. Four of these could possibly be part of the same halo structure and cover a region of sky that is at least 40 degrees across. The scientists discovered the star structures while analyzing postions, colors, and brightnesses of five million stars detected in the Sloan Digital Sky Survey. The survey is an international scientific project whose goal is to catalogue the universe more accurately. The results returned from the survey have yielded a “deeper, more global picture of the Milky Way Galaxy,” said Newberg and Yanny. A surpisingly large number of blue stars were discovered within twenty degrees of the galactic plane, said Newberg and Yanny. These blue stars could be part of a disrupted dwarf galaxy, a disk-like group of stars that is puffier than standard models of stellar disks in the Milky Way Galaxy and flatter than the halo’s spherical distribution. Newberg’s and Yanny’s research has raised questions about the standard model of the Milky Way Galaxy and the history of its formation. “Stars in the halo appear to be grouped into distinct streams in the sky,” said Yanny. “A careful look at the stellar properties shows they come from yet unidentified parent populations—perhaps other dwarf galaxies which have long since been torn apart.” “The clumpiness of the stellar distribution in the Milky Way halo suggests that our galactic model needs to be reconsidered,” said Newberg. “Although we originally set out to measure properties of a smooth halo, we now find it difficult to determine which, if any, of the structures of the halo belong to that population.” Newberg suggested that their findings could influence astronomical research in the study of galactic structures, the distribution of mass in the Milky Way Galaxy, the evolution of the galaxy, and the formation of the galaxy in the early universe. Newberg and Yanny—along with 17 other SDSS researchers—are the principle writers of an SDSS paper that will be published in the Astrophysical Journal. The paper, titled “Halo Streams and Milky Way Galaxy Compositions from the Sloan Digital Sky Survey,” can be read online at http://xxx.lanl.gov/abs/astro-ph/0111095. Posted 01-16-2002 at 8:03PM Copyright 2000-2006 The Polytechnic Comments, questions? E-mail the Webmaster. Site design by Jason Golieb.