*Description*: A new image taken with NASA's Hubble Space Telescope provides a detailed look at the tattered remains of a supernova explosion known as Cassiopeia A (Cas A). It is the youngest known remnant from a supernova explosion in the Milky Way. The new Hubble image shows the complex and intricate structure of the star's shattered fragments. The image is a composite made from 18 separate images taken in December 2004 using Hubble's Advanced Camera for Surveys (ACS), and it shows the Cas A remnant as a broken ring of bright filamentary and clumpy stellar ejecta. These huge swirls of debris glow with the heat generated by the passage of a shockwave from the supernova blast. The various colors of the gaseous shards indicate differences in chemical composition. Bright green filaments are rich in oxygen, red and purple are sulfur, and blue are composed mostly of hydrogen and nitrogen. A supernova such as the one that resulted in Cas A is the explosive demise of a massive star that collapses under the weight of its own gravity. The collapsed star then blows its outer layers into space in an explosion that can briefly outshine its entire parent galaxy. Cas A is relatively young, estimated to be only about 340 years old. Hubble has observed it on several occasions to look for changes in the rapidly expanding filaments. In the latest observing campaign, two sets of images were taken, separated by nine months. Even in that short time, Hubble's razor-sharp images can observe the expansion of the remnant. Comparison of the two image sets shows that a faint stream of debris seen along the upper left side of the remnant is moving with high speed - up to 31 million miles per hour (fast enough to travel from Earth to the Moon in 30 seconds!). Cas A is located ten thousand light-years away from Earth in the constellation of Cassiopeia. Supernova explosions are the main source of elements more complex than oxygen, which are forged in the extreme conditions produced in these events. The analysis of such a nearby, relatively young and fresh example is extremely helpful in understanding the evolution of the universe. For more information, contact: Robert A. Fesen,Dartmouth College, Hanover, New Hampshire, (phone) 603-646-2949, (e-mail) fesen@snr.dartmouth.edu Lars Lindberg Christensen, Hubble/ESA, Garching, Germany (phone) 011-49-89-3200-6306, (cell) 011-49-173-3872-621; (e-mail) lars@eso.org Ray Villard, Space Telescope Science Institute, Baltimore, Md., (phone) 410-338-4514, (e-mail) villard@stsci.edu Keith Noll, Space Telescope Science Institute, Baltimore, Md., (phone) 410-338-1828, (e-mail) noll@stsci.edu Technical facts about this news release: About the Object Object Name: Cassiopeia A Object Description: Supernova Remnant Position (J2000): R.A. 23h 23m 24s Dec. +58° 48' 54" Constellation: Cassiopeia Distance: About 10,000 light-years 3,100 parsecs away. Dimensions: This image is 8.5 arcminutes (25 light-years or 7.7 parsecs) wide. The bright remnant shell has a diameter of about 4 parsecs (13 light-years). About the Data Data Description: This image was created from HST data from the following proposals: 9890 and 10286, both by: R. Fesen (Dartmouth College), J. Morse (NASA Goddard Space Flight Center), J. Raymond (Harvard-Smithsonian Center for Astrophysics), R. Chevalier (University of Virginia), and M. Dopita (Australian National University). Instrument: ACS/WFC Exposure Date(s): March, 2004 and December, 2004 Exposure Time: 2.3 days Filters: F625W (SDSS "r"), F775W (SDSS "i") , and F850LP (SDSS "z") About the Image Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration Release Date: August 29, 2006 Colors This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope using several different filters. Three filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: F625W blue F775W green F850LP red Orientation/Scale: Supernova Remnant Cassiopeia A - December 2004 [ http://imgsrc.hubblesite.org/hu/db/2006/30/images/a/formats/compass_large_web.jpg ] What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. A new image taken with NASA's Hubble Space Telescope provides a detailed look at the tattered remains of a supernova explosion known as Cassiopeia A (Cas A). It is the youngest known remnant from a supernova explosion in the Milky Way. The new Hubble image shows the complex and intricate structure of the star's shattered fragments. The image is a composite made from 18 separate images taken in December 2004 using Hubble's Advanced Camera for Surveys (ACS). *News Release Number:*: STScI-2006-30a
