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News Release Archive:

News Release 79 of 295

March 12, 2009 09:00 AM (EDT)

News Release Number: STScI-2009-11

Hubble Provides New Evidence for Dark Matter Around Small Galaxies

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Image: Perseus Cluster Dwarf Galaxies

Perseus Cluster Dwarf GalaxiesSTScI-PRC2009-11

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ABOUT THIS IMAGE:

These four dwarf galaxies are part of a census of small galaxies in the tumultuous heart of the nearby Perseus galaxy cluster.

The galaxies appear smooth and symmetrical, suggesting that they have not been tidally disrupted by the pull of gravity in the dense cluster environment. Larger galaxies around them, however, are being ripped apart by the gravitational tug of other galaxies.

The images, taken by NASA's Hubble Space Telescope, are evidence that the undisturbed galaxies are enshrouded by a "cushion" of dark matter, which protects them from their rough-and-tumble neighborhood.

Dark matter is an invisible form of matter that accounts for most of the universe's mass. Astronomers have deduced the existence of dark matter by observing its gravitational influence on normal matter, consisting of stars, gas, and dust.

Observations by Hubble's Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus Cluster, located 250 million light-years away and one of the closest galaxy clusters to Earth. Of those galaxies, 17 are new discoveries.

The images were taken in 2005.

Image Type: Astronomical/Annotated

Credit: NASA, ESA, and C. Conselice and S. Penny (University of Nottingham)

NEWS RELEASE IMAGES

The above montage includes these images:

Perseus Dwarf Galaxy [CGW2003] J031931.7+4131 Image Type: Astronomical Perseus Dwarf Galaxy [CGW2003] J031931.7+4131 Perseus Dwarf Galaxy [CGW2003] J031910.4+4129 Image Type: Astronomical Perseus Dwarf Galaxy [CGW2003] J031910.4+4129 Perseus Dwarf Galaxy [CGW2003] J031900.4+4129 Image Type: Astronomical Perseus Dwarf Galaxy [CGW2003] J031900.4+4129 Perseus Dwarf Galaxy [CGW2003] J031905.2+4134 Image Type: Astronomical Perseus Dwarf Galaxy [CGW2003] J031905.2+4134

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