Baby Stars Finally Found in Jumbled Galactic Center

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Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

NEWS RELEASE: 2009-097 June 10, 2009

Baby Stars Finally Found in Jumbled Galactic Center

PASADENA, Calif. -- Astronomers have at last uncovered newborn stars at the frenzied center
of our Milky Way galaxy. The discovery was made using the infrared vision of NASA's Spitzer
Space Telescope.

The heart of our spiral galaxy is cluttered with stars, dust and gas, and at its very center, a
supermassive black hole. Conditions there are harsh, with fierce stellar winds, powerful shock
waves and other factors that make it difficult for stars to form. Astronomers have known that
stars can form in this chaotic place, but they're baffled as to how this occurs. Confounding the
problem is all the dust standing between us and the center of our galaxy. Until now, nobody had
been able to definitively locate any baby stars.

"These stars are like needles in a haystack," said Solange Ramirez, the principal investigator of
the research program at NASA's Exoplanet Science Institute at the California Institute of
Technology, Pasadena. "There's no way to find them using optical light, because dust gets in the
way. We needed Spitzer's infrared instruments to cut through the dust and narrow in on the
objects."

The team plans to look for additional baby stars in the future, and ultimately to piece together
what types of conditions allow stars to form in such an inhospitable environment as our galaxy's
core.

"By studying individual stars in the galactic center, we can better understand how stars are
formed in different interstellar environments," said Deokkeun An of the Infrared Processing and
Analysis Center at Caltech, lead author of a paper submitted for publication in the Astrophysical
Journal. "The Milky Way galaxy is just one of more than hundreds of billions of galaxies in the
visible universe. However, our galaxy is so special because we can take a closer look at its
individual stellar components." An started working on this program while a graduate student at
Ohio State University, Columbus, under the leadership of Ohio State astronomer Kris Sellgren,
the co-investigator on the project.

The core of the Milky Way is a mysterious place about 600 light-years across (light would take
600 years to travel from one end to the other). While this is just a fraction of the size of the entire
Milky Way, which is about 100,000 light-years across, the core is stuffed with 10 percent of all
the gas in the galaxy -- and loads and loads of stars.

Before now, there were only a few clues that stars can form in the galaxy's core. Astronomers
had found clusters of massive adolescent stars, in addition to clouds of charged gas -- a sign that
new stars are beginning to ignite and ionize surrounding gas. Past attempts had been unsuccessful
in finding newborn stars, or as astronomers call them, young stellar objects.

Ramirez and colleagues began their search by scanning large Spitzer mosaics of our galactic
center. They narrowed in on more than 100 candidates, but needed more detailed data to confirm
the stars' identities. Young stellar objects, when viewed from far away, can look a lot like much
older stars. Both types of stars are very dusty, and the dust lying between us and them obscures
the view even further.

To sort through the confusion, the astronomers looked at their candidate stars with Spitzer's
spectrograph – an instrument that breaks light apart to reveal its rainbow-like array of infrared
colors. Molecules around stars leave imprints in their light, which the spectrograph can detect.

The results revealed three stars with clear signs of youth, for example, certain warm, dense gases.
These youthful features are found in other places in the galaxy where stars are being formed.

"It is amazing to me that we have found these stars," said Ramirez. "The galactic center is a very
interesting place. It has young stars, old stars, black holes, everything. We started mining a
catalog of about 1 million sources and managed to find three young stars -- stars that will help
reveal the secrets at the core of the Milky Way."

The young stellar objects are all less than about 1 million years old. They are embedded in
cocoons of gas and dust, which will eventually flatten to disks that, according to theory, later
lump together to form planets.

Other collaborators include Richard Arendt of NASA's Goddard Space Flight Center, Greenbelt,
Md.; A. C. Adwin Boogert of NASA's Herschel Science Center, Caltech in Pasadena; Mathias
Schultheis of the Besancon Observatory in France; Susan Stolovy of NASA's Spitzer Science
Center, Caltech in Pasadena; Angela Cotera of SETI Institute, Mountain View, Calif.; and
Thomas Robitaille and Howard Smith of Harvard Smithsonian Center for Astrophysics,
Cambridge, Mass.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope
mission for NASA's Science Mission Directorate, Washington. Science operations are conducted
at the Spitzer Science Center at Caltech in Pasadena. Caltech manages JPL for NASA. For more
information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and
http://www.nasa.gov/spitzer .

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