Credit: NASA/JPL-Caltech/H. Kobulnicky (Univ. of Wyoming)

Spitzer Digs Up Galactic Fossil

This false-color image taken by NASA's Spitzer Space Telescope shows a globular cluster previously hidden in the dusty plane of our Milky Way galaxy. Globular clusters are compact bundles of old stars that date back to the birth of our galaxy, 13 or so billion years ago. Astronomers use these galactic "fossils" as tools for studying the age and formation of the Milky Way.

Most clusters orbit around the center of the galaxy well above its dust-enshrouded disc, or plane, while making brief, repeated passes through the plane that each last about a million years. Spitzer, with infrared eyes that can see into the dusty galactic plane, first spotted the newfound cluster during its current pass. A visible-light image (inset) shows only a dark patch of sky.

The red streak behind the core of the cluster is a dust cloud, which may indicate the cluster's interaction with the Milky Way. Alternatively, this cloud may lie coincidentally along Spitzer's line of sight.

Follow-up observations with the University of Wyoming Infrared Observatory helped set the distance of the new cluster at about 9,000 light-years from Earth -- closer than most clusters -- and set the mass at the equivalent of 300,000 Suns. The cluster's apparent size, as viewed from Earth, is comparable to a grain of rice held at arm's length. It is located in the constellation Aquila.

Astronomers believe that this cluster may be one of the last in our galaxy to be uncovered.

This image composite was taken on April 21, 2004, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). The visible-light image is from the Digitized Sky Survey, California University of Technology, Pasadena, Calif.

About the Object	Object Name: GLIMPSE-C01 Object Type: Globular Cluster Position (J2000): RA: 18h48m49.7s Dec: -01d29m50s Distance: 3.1-5.2 kpc or 10,000-17,000 ly Constellation: Aquila
About the Data	Image Credit: NASA/JPL-Caltech/H. Kobulnicky (Univ. of Wyoming) Instrument: IRAC Wavelength: 3.6 (blue), 4.5 (green), 5.8 (orange), 8.0 (red) microns Exposure Date: 2004 April 21 Exposure Time: 2.4 sec Image Scale: 6 x 6 arcmin Orientation: North is 63 deg CCW from up Release Date: October 12, 2004
Observers	Henry Kobulnicky (Principal Investigator) - University of Wyoming B.L. Babler - University of Wisconsin-Madison T.M. Bania - Boston University R.A. Benjamin - University of Wisconsin-Whitewater B.A. Buckalew - University of Wyoming R. Canterna - University of Wyoming E. Churchwell - University of Wisconsin-Madison D. Clemens - Boston University M. Cohen - University of California-Berkley J.M. Darnel - University of Wyoming J.M. Dickey - University of Minnesota R. Indebetouw - University of Wisconsin-Madison J.M. Jackson - Boston University A. Kutyrev - NASA Goddard Space Flight Center A.P. Marston - ESTEC/SCI-SA J.S. Mathis - University of Maryland M.R. Meade - University of Wisconsin-Madison E.P. Mercer - Boston University A.J. Monson - University of Wyoming J.P. Norris - NASA Goddard Space Flight Center M.J. Pierce - University of Wyoming R. Shah - Boston University J.R. Stauffer - Caltech, Spitzer Science Center S.R. Stolovy - Caltech, Spitzer Science Center B. Uzpen - University of Wyoming C. Watson - University of Wisconsin-Madison B.A. Whitney - Space Science Institute M.J. Wolff - Space Science Institute M.G. Wolfire - University of Maryland

Individual Images

	Spitzer View Screen-Resolution (450x450): JPEG High-Resolution (900x900): JPEG | Mac TIFF | PC TIFF Credit: NASA/JPL-Caltech/H. Kobulnicky (Univ. of Wyoming)
	DSS (Visible-Light) View Screen-Resolution (450x450): JPEG High-Resolution (900x900): JPEG | Mac TIFF | PC TIFF Credit: NASA/DSS

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