No Stars in the Clouds (Forwarded)

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FOR IMMEDIATE RELEASE: January 10, 2006

No Stars in the Clouds

Search for missing galaxies in high-speed galactic gas clouds "comes up
empty," Pitt researcher finds

PITTSBURGH -- A team of astronomers from the University of Pittsburgh
and the Universitäts-Sternwarte München in Munich, Germany, announced
today in a paper presented at the meeting of the American Astronomical
Society in Washington, D.C., that their search for dwarf galaxies in
fast-moving clouds of gas has yielded no results, leading them to
suggest alternative avenues of research to find the supposedly "missing"
galaxies.

The team, which includes Regina Schulte-Ladbeck, associate dean for
undergraduate studies and professor of physics and astronomy in Pitt's
School of Arts and Sciences, and Ulrich Hopp of the
Universitäts-Sternwarte München, has been searching for stars in
high-velocity clouds. However, said Schulte-Ladbeck, "Our searches have
come up empty."

The mathematical simulations that astronomers use to establish how
galaxies were formed predict that every giant galaxy should have a few
hundred "dwarf" galaxy companions. But in our own neighborhood, the
Milky Way Galaxy, there are only 50 or so such dwarves.

One simple way to explain the difference would be if the missing dwarf
galaxies were located in high-velocity clouds, astronomer Leo Blitz of
the University of California, Berkeley, and his colleagues had
suggested. Schulte-Ladbeck and Hopp hoped to measure the distances
between the clouds and the Milky Way to obtain proof that the clouds
indeed held additional satellite galaxies of our Milky Way.

To search for stars in the clouds, the researchers took a two-pronged
approach. First, they used the Two Micron All Sky Survey, a survey
conducted by the University of Massachusetts and funded primarily by
NASA and the National Science Foundation, to look for bright stars in
circular patches of sky two degrees across, the area typically covered
by the gas clouds that make the most promising dwarf galaxy candidates.

Second, using accurate positions of where most of the hydrogen gas in
several clouds is located-supplied to them by radio astronomer Jürgen
Kerp of the University of Bonn-the researchers also trained one of the
8-meter (315-inch) telescopes of the European Southern Observatory's
Very Large Telescope, located in northern Chile's Atacama Desert, on
small regions within the clouds to search if any faint stars had formed
there. However, neither of these methods turned up any stars.

In their paper, Schulte-Ladbeck and Hopp conclude that it is unlikely
that hundreds of additional dwarf satellites of the Milky Way have been
somehow "hiding" from observers, and they encourage astronomers to
pursue other solutions to the discrepancy.

Funding for this study was provided by NASA and Pitt's School of Arts
and Sciences.