Press Release

Star Clusters Born in Wreckage of Cosmic Collisions

By SpaceRef Editor
July 19, 2001
Filed under , ,

A famous group of five compact galaxies featured in the
holiday film classic “It’s a Wonderful Life” appears in a new
image from NASA’s Hubble Space Telescope.

In the movie, angelic figures take on the form of the
galactic group called Stephan’s Quintet. But the new pictures
show the group has actually been doing some devilish things.
At least two of its galaxies have been involved in high-speed,
hit-and-run accidents, ripping stars and gas from neighboring
galaxies and tossing them into space.

The image, taken by Hubble’s Wide Field and Planetary
Camera 2, is online at
http://oposite.stsci.edu/pubinfo/pr/2001/22 and
http://www.jpl.nasa.gov/images/wfpc . The camera was designed
and built by NASA’s Jet Propulsion Laboratory, Pasadena,
Calif.

The close-up view of Stephan’s Quintet reveals a string
of bright star clusters sparkling like a diamond necklace. The
clusters, each harboring up to millions of stars, were born
from the violent interactions between some members of the
group. The rude encounters also have distorted the galaxies’
shapes, creating elongated spiral arms and long, gaseous
streamers.

The photo showcases three regions of star birth: the
long, sweeping tail and spiral arms of the galaxy NGC 7319
(near center); the gaseous debris of two galaxies, NGC 7318B
and NGC 7318A (top right); and the area north of those
galaxies, dubbed the northern starburst region (top left).

The clusters’ bluish color indicates that they’re
relatively young — between about 2 million to more than 1
billion years old. The brilliant star clusters in NGC 7318B’s
spiral arm and the northern starburst region are between 2
million and more than 100 million years old. NGC 7318B
instigated the starburst by barreling through the region. The
bully galaxy is just below NGC 7318A at top right.

Although NGC 7318B appears dangerously close to NGC
7318A, it’s traveling too fast to merge with its neighbor. The
partial galaxy on the far right is NGC 7320, a foreground
galaxy not physically bound to the other galaxies in the
picture.

About 20 to 50 of the clusters in the northern starburst
region reside far from the coziness of galaxies. The clusters
were born about 150,000 light-years from the nearest galaxy.

Another galaxy, NGC 7320C, which is no longer part of the
group and is not seen in the photo, plowed through the quintet
several hundred million years ago. It pulled out the long
tail of gaseous debris from NGC 7319. The clusters in NGC
7319’s streaming tail are 10 million to 500 million years old
and may have formed at the time of the violent collision. The
faint bluish object at the tip of the tail is a young dwarf
galaxy, which formed in the gaseous debris.

Stephan’s Quintet is in the constellation Pegasus, 270
million light-years from Earth.

The pictures in this mosaic were taken by the Wide Field
Planetary Camera 2 on Dec. 30, 1998 and June 17, 1999.
Additional information about the Hubble Space Telescope is
online at http://www.stsci.edu . More information about the
Wide Field and Planetary Camera 2 is at
http://wfpc2.jpl.nasa.gov .

The Space Telescope Science Institute, Baltimore, Md.,
manages space operations for Hubble for NASA’s Office of Space
Science, Washington, D.C. The institute is operated by the
Association of Universities for Research in Astronomy, Inc.,
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. JPL is a division of the California Institute of
Technology in Pasadena.

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07/19/01 JP

#2001-149

Image credits: NASA, Jayanne English (University of Manitoba),
Sally Hunsberger (Pennsylvania State University), Zolt Levay
(Space Telescope Science Institute), Sarah Gallagher
(Pennsylvania State University), and Jane Charlton

SpaceRef staff editor.