Andrew Yee[_1_]
January 17th 08, 05:19 AM
National Radio Astronomy Observatory
P.O. Box O
Socorro, NM 87801
http://www.nrao.edu
Contact:
Dave Finley, Public Information Officer
(505) 835-7302
EMBARGOED For Release: 10:00 a.m., CST, Friday, January 11, 2008
Massive Gas Cloud Speeding Toward Collision With Milky Way
A giant cloud of hydrogen gas is speeding toward a collision with our Milky
Way Galaxy, and when it hits -- in less than 40 million years -- it may set
off a spectacular burst of stellar fireworks.
"The leading edge of this cloud is already interacting with gas from our
Galaxy," said Felix J. Lockman, of the National Radio Astronomy Observatory
(NRAO), leader of a team of astronomers who used the National Science
Foundation's Robert C. Byrd Green Bank Telescope (GBT) to study the object.
The scientists presented their findings to the American Astronomical
Society's meeting in Austin, Texas.
The cloud, called Smith's Cloud, after the astronomer who discovered it in
1963, contains enough hydrogen to make a million stars like the Sun. Eleven
thousand light-years long and 2,500 light-years wide, it is only 8,000
light-years from our Galaxy's disk. It is careening toward our Galaxy at
more than 150 miles per second, aimed to strike the Milky Way's disk at an
angle of about 45 degrees.
"This is most likely a gas cloud left over from the formation of the Milky
Way or gas stripped from a neighbor galaxy. When it hits, it could set off a
tremendous burst of star formation. Many of those stars will be very
massive, rushing through their lives quickly and exploding as supernovae.
Over a few million years, it'll look like a celestial New Year's
celebration, with huge firecrackers going off in that region of the Galaxy,"
Lockman said.
When Smith's Cloud was first discovered, and for decades after, the
available images did not have enough detail to show whether the cloud was
part of the Milky Way, something being blown out of the Milky Way, or
something falling in.
Lockman and his colleagues used the GBT to make an extremely detailed study
of hydrogen in Smith's Cloud. Their observations included nearly 40,000
individual pointings of the giant telescope to cover the cloud with
unprecedented sensitivity and resolution. Smith's Cloud is about 15 degrees
long in the sky, 30 times the width of the full moon.
"If you could see this cloud with your eyes, it would be a very impressive
sight in the night sky," Lockman said. "From tip to tail it would cover
almost as much sky as the Orion constellation. But as far as we know it is
made entirely of gas -- no one has found a single star in it."
The detailed GBT study dramatically changed the astronomers' understanding
of the cloud. Its velocity shows that it is falling into the Milky Way, not
leaving it, and the new data show that it is plowing up Milky Way gas before
it as it falls.
"Its shape, somewhat similar to that of a comet, indicates that it's already
hitting gas in our Galaxy's outskirts," Lockman said. "It is also feeling a
tidal force from the gravity of the Milky Way and may be in the process of
being torn apart. Our Galaxy will get a rain of gas from this cloud, then in
about 20 to 40 million years, the cloud's core will smash into the Milky
Way's plane," Lockman explained.
The cloud will likely strike a region somewhat farther from the Galactic
center than our Solar System and about 90 degrees ahead of us in the Milky
Way disk. The collision may trigger a period of rapid star formation fueled
by the new gas and the shock from the collision. Some theories say that the
ring of bright stars near the Sun, called Gould's Belt, was created by just
such a collision event.
Lockman worked with Robert A. Benjamin and A.J. Heroux of the University of
Wisconsin-Whitewater and Glen I. Langston of NRAO.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by Associated
Universities, Inc.
[NOTE: Images supporting this release are available at
http://www.nrao.edu/pr/2008/smithscloud/ ]
P.O. Box O
Socorro, NM 87801
http://www.nrao.edu
Contact:
Dave Finley, Public Information Officer
(505) 835-7302
EMBARGOED For Release: 10:00 a.m., CST, Friday, January 11, 2008
Massive Gas Cloud Speeding Toward Collision With Milky Way
A giant cloud of hydrogen gas is speeding toward a collision with our Milky
Way Galaxy, and when it hits -- in less than 40 million years -- it may set
off a spectacular burst of stellar fireworks.
"The leading edge of this cloud is already interacting with gas from our
Galaxy," said Felix J. Lockman, of the National Radio Astronomy Observatory
(NRAO), leader of a team of astronomers who used the National Science
Foundation's Robert C. Byrd Green Bank Telescope (GBT) to study the object.
The scientists presented their findings to the American Astronomical
Society's meeting in Austin, Texas.
The cloud, called Smith's Cloud, after the astronomer who discovered it in
1963, contains enough hydrogen to make a million stars like the Sun. Eleven
thousand light-years long and 2,500 light-years wide, it is only 8,000
light-years from our Galaxy's disk. It is careening toward our Galaxy at
more than 150 miles per second, aimed to strike the Milky Way's disk at an
angle of about 45 degrees.
"This is most likely a gas cloud left over from the formation of the Milky
Way or gas stripped from a neighbor galaxy. When it hits, it could set off a
tremendous burst of star formation. Many of those stars will be very
massive, rushing through their lives quickly and exploding as supernovae.
Over a few million years, it'll look like a celestial New Year's
celebration, with huge firecrackers going off in that region of the Galaxy,"
Lockman said.
When Smith's Cloud was first discovered, and for decades after, the
available images did not have enough detail to show whether the cloud was
part of the Milky Way, something being blown out of the Milky Way, or
something falling in.
Lockman and his colleagues used the GBT to make an extremely detailed study
of hydrogen in Smith's Cloud. Their observations included nearly 40,000
individual pointings of the giant telescope to cover the cloud with
unprecedented sensitivity and resolution. Smith's Cloud is about 15 degrees
long in the sky, 30 times the width of the full moon.
"If you could see this cloud with your eyes, it would be a very impressive
sight in the night sky," Lockman said. "From tip to tail it would cover
almost as much sky as the Orion constellation. But as far as we know it is
made entirely of gas -- no one has found a single star in it."
The detailed GBT study dramatically changed the astronomers' understanding
of the cloud. Its velocity shows that it is falling into the Milky Way, not
leaving it, and the new data show that it is plowing up Milky Way gas before
it as it falls.
"Its shape, somewhat similar to that of a comet, indicates that it's already
hitting gas in our Galaxy's outskirts," Lockman said. "It is also feeling a
tidal force from the gravity of the Milky Way and may be in the process of
being torn apart. Our Galaxy will get a rain of gas from this cloud, then in
about 20 to 40 million years, the cloud's core will smash into the Milky
Way's plane," Lockman explained.
The cloud will likely strike a region somewhat farther from the Galactic
center than our Solar System and about 90 degrees ahead of us in the Milky
Way disk. The collision may trigger a period of rapid star formation fueled
by the new gas and the shock from the collision. Some theories say that the
ring of bright stars near the Sun, called Gould's Belt, was created by just
such a collision event.
Lockman worked with Robert A. Benjamin and A.J. Heroux of the University of
Wisconsin-Whitewater and Glen I. Langston of NRAO.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by Associated
Universities, Inc.
[NOTE: Images supporting this release are available at
http://www.nrao.edu/pr/2008/smithscloud/ ]