Astronomers Report Mysterious Giant Star Clusters (Forwarded)

Office of Media Relations
University of California-Los Angeles

Media Contacts:
Stuart Wolpert
(310) 206-0511 / (310) 825-2585

FOR IMMEDIATE RELEASE: Tuesday, January 10, 2006

Astronomers Report Mysterious Giant Star Clusters

An international team of astronomers reported evidence for the formation
of mysterious "super star clusters" Jan. 9 at the annual meeting of the
American Astronomical Society in Washington, D.C. These star clusters are
the likely precursors to the familiar globular clusters of the Milky Way;
however in our galaxy, globular clusters are all believed to be older than
10 billion years -- close to the age of the universe itself -- and none
are forming.

Using the Very Large Array Telescope, the astronomers detected
radio-infrared "super nebulae" around giant star clusters in the process
of formation in a dozen nearby galaxies.

"The super nebulae are gas clouds heated by intense ultraviolet light from
young super star clusters," said Chao-Wei Tsai, UCLA astronomy graduate
student and leader of the team. "The star clusters are young and still
hidden within their birth clouds. Although we cannot see the clusters
directly, we can clearly detect the infrared and radio emissions from the
hot gas surrounding them."

"The super star clusters hidden within these super nebulae are probably a
lot like globular clusters in our own Milky Way, only younger, and they
can contain up to a million young stars," said Jean Turner, UCLA professor
of physics and astronomy, and a member of the team, along with Sara C.
Beck of Tel Aviv University. "The mystery is why our own Milky Way no
longer forms globular star clusters and hasn't for 10 billion years. These
galaxies still can. We want to know why. This is star formation on
steroids."

Super star clusters pack a huge number of bright and blue stars into a
very small volume of space, with a density of stars up to a million times
higher than near the sun. The radiant power emitted by these clusters can
be up to a billion times the sun's wattage, in a region only a few light
years across.

"The brightest of even one of these stars at the distance of the sun could
charge a solar-powered car in one second with enough energy to drive from
Los Angeles to San Francisco!" Turner said.

The researchers obtained their radio and infrared images of the super
nebulae using the Very Large Array of the National Radio Astronomy
Observatory, a facility of the National Science Foundation, and the W. M.
Keck Observatory in Hawaii, operated jointly by the University of
California and the California Institute of Technology, with support from
NASA.

The discovery of young super nebulae around these potential proto-globular
clusters was made by a team led by Beck and Turner several years ago. This
latest result shows just how common young super clusters outside the Milky
Way are.

"Life on a planet orbiting a star in a young super star cluster would be
very different," mused Beck. "There would be light coming from every
direction, and no darkness or night -- sunlight would be very blue -- it
would be a strange place to live."

IMAGE CAPTION:
[http://newsroom.ucla.edu/NewsRelease...ages/6744a.jpg (280KB)]
Super star clusters and super nebulae in the nearby galaxy NGC 4214. A
Keck Telescope infrared image is superimposed on a Hubble Space Telescope
image, with visible star clusters shown in blue. The black dots, revealed
in radiographs, are young super star clusters in the process of forming.

Credit: Very Large Array Telescope; W.M. Keck observatory; Hubble Space
Telescope