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First tile gap filler
This extended movie shows Steve Robinson riding the station's robot arm, moving within reach of Discovery's underside and successfully pulling out the first protruding tile gap filler. (6min 45sec file)
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Second tile gap filler
This extended movie shows Steve Robinson successfully pulling out the second protruding tile gap filler. (9min 23sec file)
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Storage platform
The External Stowage Platform-2 designed to hold spares and replacement equipment for the space station is attached to the Quest airlock module's outer hull during the spacewalk. (6min 29sec file)
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Station experiments
Japanese astronaut Soichi Noguchi climbed 60 feet above Discovery's payload bay to the space station's P6 solar array truss to attach the Materials International Space Station Experiment-5 package. (4min 08sec file)
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Opening the suitcase
Noguchi deploys the MISSE-5 package, revealing a host of material samples to the space environment for extended exposure. (3min 43sec file)
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Atop the station
Noguchi's helmet-mounted camera provides a stunning view atop the P6 truss showing Discovery to his right and the Russian segment of the space station on his left. (2min 31sec file)
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Hubble pinpoints doomed star that exploded
Posted: August 15, 2005

Amidst the glitter of billions of stars in the majestic spiral galaxy called the Whirlpool (M51), a massive star abruptly ends its life in a brilliant flash of light. NASA's Hubble Space Telescope snapped images of the exploding star, called supernova (SN) 2005cs, 12 days after its discovery. Astronomers then compared those photos with Hubble images of the same region before the supernova blast to pinpoint the progenitor star (the star that exploded).

Credit: NASA, ESA, W. Li and A. Filippenko (University of California, Berkeley), S. Van Dyk (Spitzer Science Center, Caltech), S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA)
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The color image at left shows a section of M51 taken in January 2005 with the Advanced Camera for Surveys. The small green square marks the region where the progenitor star resides. The lower-right image shows a picture of SN 2005cs (the central bright object), taken July 11, 2005, by Hubble. By comparing the lower-right image with the color image at left, astronomers identified the supernova's progenitor star [marked by the arrow in the (pre-explosion) upper-right image]. The star was found to be a red supergiant whose mass is about seven to 10 times that of the Sun.

Every second, a star somewhere in the universe explodes as a supernova. Astronomers cannot see every supernova. Of the supernovas astronomers have seen, only six progenitor stars have been identified. Since Hubble can easily resolve stars in nearby galaxies, such as the Whirlpool, it allowed astronomers to track down the exploding star's identity in archival pictures.

SN 2005cs belongs to a class of exploding stars called "Type II-plateau." A supernova of this type results from the collapse and subsequent explosion of a massive star whose light remains at a constant brightness (a "plateau") for a period of time.

This finding is consistent with the idea that the progenitors of supernova explosions are red supergiant stars with masses eight to 15 times the Sun's mass. The progenitor star was found to be at the low end of the mass range for supernova explosions. Stars with masses lower than eight solar masses do not explode as supernovae at all, but rather contract to white dwarfs and blow off their outer atmospheres to become planetary nebulae.

Identification of the progenitor star was first reported in IAU Circulars 8556 and 8565 on July 3 and July 12, respectively, by Drs. Weidong Li and Alex Filippenko (University of California, Berkeley) and Schuyler Van Dyk (Spitzer Science Center, Caltech). The team submitted a paper describing their research to The Astrophysical Journal on July 18. A European team composed of Drs. Justyn Maund (Institute of Astronomy, University of Cambridge), Stephen Smartt (Queen's University, Belfast) and John Danziger (Trieste Observatory) reported similar results in a letter submitted on July 21 to the Monthly Notices of the Royal Astronomical Society.

The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).