Amateur stargazers may spot the Orion Nebula as a fuzzy
patch in the constellation Orion, but they cannot see an interstellar birthing
ground that spans the region of sky from above Orion's head to below his feet.
Now astronomers have completed the most wide-ranging census
of baby stars in and around the Orion nebula, and found a stellar nursery
that's both chaotic
and crowded. The work represents the first complete study of young stars,
their gaseous clouds of dust and supersonic jets of hydrogen molecules shooting
out from the poles of each star.
Jets arise as young stars are born from a rotating cloud
of gas and dust, but usually die out once a star has fully ignited and stopped
consuming the surrounding material. In this case, the jets became
signals that pinpointed the location of baby stars hidden within the
stellar birthing grounds.
"With such a large number of young stars, we can
study the 'demographics' of star birth," said Tom Megeath, an astronomer at
the University of Toledo in Ohio. "This study will give us an idea of how
long it takes baby stars to bulk up by pulling in gas from the surrounding cloud,
what ultimately stops a star from growing bigger, and how a star's birth is
influenced by other stars in the stellar nursery."
The Orion
nebula represents just a blister on the surface of the much larger cloud.
Astronomers turned to the United Kingdom Infra-Red Telescope (UKIRT) and the
Spitzer Space Telescope to peer through the cloud using infrared vision, and
also used the Institut de Radio Astronomie Millimetrique radio telescope in
France to see beyond infrared at short radio wavelengths.
Such international collaboration allowed astronomers to
match up powerful gas jets with their young
star origins, and find the cradles within the clouds where stars were
created.
"Each jet is travelling at tens or even hundreds of
miles per second; the jets extend across many trillions of miles of
interstellar space," said Chris Davis, an astronomer for UKIRT in Hawaii.
UKIRT's wide field camera alone found more than 110
individual jets from the one region of the Milky Way. The results were
presented on April 20 at the European Week of Astronomy and
Space Science at the University of Hertfordshire, UK.
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