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| The Sculptor Galaxy |
Excerpt from sciencerecorder.com
Starburst galaxies are named for
their ability to convert gasses rapidly into new stars, at an
accelerated speed that can sometimes be 1,000 times more rapid than your
average spiral galaxy, such as the Milky Way. Why the disparity? In
order to further investigate the reason that some galaxies seem to
“burst” into being, whereas others take the better part of a few billion
years, an international team of astronomers analyzed a cluster of
star-forming gas clouds in the heart of NGC 253 – the Sculptor Galaxy,
with the aid of the Atacama Large Millimeter/submillimeter Array (ALMA).
The Sculptor Galaxy is among starburst galaxies closest to the Milky
Way.
“All stars form in dense clouds of dust and gas,” said Adam Leroy, in an interview with Astronomy magazine.
Leroy is an astronomer at Ohio State University in Columbus. “Until
now, however, scientists struggled to see exactly what was going on
inside starburst galaxies that distinguished them from other
star-forming regions.”
Therefore, Leroy and his colleagues turn to the ALMA which is capable
of examining star changing structures even in systems as distant as
Sculptor. Already, they have successfully charted distribution and
movement of various molecules within several clouds located at the
Sculptor Galaxy’s core.
Because NGC 253, which is disk-shaped, is in the stages of a very
intense starburst and located approximately 11.5 million light-years
from home, it is the perfect target for study. ALMA picks it up with
remarkable precision and resolution, so much so that the team was able
to isolate and identify ten different stellar ‘nurseries,’ in which
stars were in the process of forming. To appreciate the magnitude of
this feat, it would have been impossible with previous telescopes, which
blurred the regions together into one glow.
“There is a class of galaxies and parts of galaxies, we call them
starbursts, where we know that gas is just plain better at forming
stars,” said Leroy. “To understand why, we took one of the nearest such
regions and pulled it apart — layer by layer — to see what makes the gas
in these places so much more efficient at star formation.”
More importantly, they recognized the distribution of several 40
millimeter-wavelength “signatures,” that given off by various molecules
at the center of Sculptor Galaxy, signaling that a number of conditions
were responsible for the development of these stars. This accounts for
the diversity of the states of different stars corresponding to where
they are found in star-forming clouds. One important compound, all too
familiar and unwelcome on Earth, carbon monoxide (CO), correlates with
massive envelopes of gases that are less dense within the stellar
nurseries. Others, such as hydrogen cyanide (HCN), were present in the
more dense reaches of active star formation. The rarer the molecules,
for example, H13CN and H13CO+, suggest regions that are even denser.
Indeed, when the data was compared, researchers found that the gas
clouds of the Sculptor Galaxy were ten times denser than those found in
spiral galaxies, suggesting that because the clouds are so tightly
packed, they can form star clusters much more rapidly than the Milky
Way. At the same time, they give us further insight as to how stars are
born, showing us the physical changes along the way, allowing
astronomers a working model to compare with our own galaxy.
“These differences have wide-ranging implications for how galaxies
grow and evolve,” concluded Leroy. “What we would ultimately like to
know is whether a starburst like Sculptor produces not just more stars,
but different types of stars than a galaxy like the Milky Way. ALMA is
bringing us much closer to that goal.”
Source Article from http://feedproxy.google.com/~r/AscensionEarth2012/~3/TFc_a1lHpMY/alma-uncovers-stellar-nurseries-in.html
ALMA uncovers stellar nurseries in the Sculptor Galaxy, 11.5 million light years from home
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