Andrew Yee[_1_]
May 21st 08, 11:39 PM
Robert Naeye / Rob Gutro
Goddard Space Flight Center, Greenbelt, Md. May 21, 2008
301-286-4453/4044
PRESS RELEASE: 08-43
NASA'S SWIFT SATELLITE CATCHES FIRST SUPERNOVA IN THE ACT OF EXPLODING
GREENBELT, Md. -- Thanks to a fortuitous observation with NASA's Swift
satellite, astronomers for the first time have caught a star in the act
of exploding. Astronomers have previously observed thousands of stellar
explosions, known as supernovae, but they have always seen them after
the fireworks were well underway.
"For years we have dreamed of seeing a star just as it was exploding,
but actually finding one is a once in a lifetime event," says team
leader Alicia Soderberg, a Hubble and Carnegie-Princeton Fellow at
Princeton University in Princeton, N.J. "This newly born supernova is
going to be the Rosetta stone of supernova studies for years to come."
A typical supernova occurs when the core of a massive star runs out of
nuclear fuel and collapses under its own gravity to form an ultradense
object known as a neutron star. The newborn neutron star compresses and
then rebounds, triggering a shock wave that plows through the star's
gaseous outer layers and blows the star to smithereens. Astronomers
thought for nearly four decades that this shock "break-out" will produce
bright X-ray emission lasting a few minutes.
But until this discovery, astronomers have never observed this signal.
Instead, they have observed supernovae brightening days or weeks later,
when the expanding shell of debris is energized by the decay of
radioactive elements forged in the explosion. "Seeing the shock
break-out in X-rays can give a direct view of the exploding star in the
last minutes of its life and also provide a signpost to which
astronomers can quickly point their telescopes to watch the explosion
unfold," says Edo Berger, a Carnegie-Princeton Fellow at Princeton
University.
Soderberg's discovery of the first shock breakout can be attributed to
luck and Swift's unique design. On January 9, 2008, Soderberg and Berger
were using Swift to observe a supernova known as SN 2007uy in the spiral
galaxy NGC 2770, located 90 million light-years from Earth in the
constellation Lynx. At 9:33 a.m. EST they spotted an extremely bright
5-minute X-ray outburst in NGC 2770. They quickly recognized that the
X-rays were coming from another location in the same galaxy.
In a paper appearing in the May 22 Nature, Soderberg and 38 colleagues
show that the energy and pattern of the X-ray outburst is consistent
with a shock wave bursting through the surface of the progenitor star.
This marks the birth of the supernova now known as SN 2008D.
Although astronomers were lucky that Swift was observing NGC 2770 just
at the moment when SN 2008D's shock wave was blowing up the star, Swift
is well equipped to study such an event because of its multiple
instruments observing in gamma rays, X-rays, and ultraviolet light. "It
was a gift of nature for Swift to be observing that patch of sky when
the supernova exploded. But thanks to Swift's flexibility, we have been
able to trace its evolution in detail every day since," says Swift lead
scientist Neil Gehrels of NASA's Goddard Space Flight Center in
Greenbelt, Md.
Due to the significance of the X-ray outburst, Soderberg immediately
mounted an international observing campaign to study SN 2008D.
Observations were made with major telescopes such as the Hubble Space
Telescope, the Chandra X-ray Observatory, the Very Large Array in New
Mexico, the Gemini North telescope in Hawaii, the Keck I telescope in
Hawaii, the 200-inch and 60-inch telescopes at the Palomar Observatory
in California, and the 3.5-meter telescope at the Apache Point
Observatory in New Mexico.
The combined observations helped Soderberg and her colleagues pin down
the energy of the initial X-ray outburst, which will help theorists
better understand supernovae. The observations also show that SN 2008D
is an ordinary Type Ibc supernova, which occurs when a massive, compact
star explodes. Significantly, radio and X-ray observations found no
evidence that a jet played a role in the explosion, ruling out a rare
type of stellar explosion known as a gamma-ray burst.
"This was a typical supernova," says Swift team member Stefan Immler of
NASA Goddard. "The significance is not the explosion itself, but the
fact that we were able to see the star blow up in real time, which gives
us unprecedented insight into the explosion process."
For related images to this story, please visit on the Web:
http://www.nasa.gov/centers/goddard/news/topstory/2008/swift_supernova.html
For more information on Swift, please visit:
http://www.nasa.gov/mission_pages/swift/main/index.html
Goddard Space Flight Center, Greenbelt, Md. May 21, 2008
301-286-4453/4044
PRESS RELEASE: 08-43
NASA'S SWIFT SATELLITE CATCHES FIRST SUPERNOVA IN THE ACT OF EXPLODING
GREENBELT, Md. -- Thanks to a fortuitous observation with NASA's Swift
satellite, astronomers for the first time have caught a star in the act
of exploding. Astronomers have previously observed thousands of stellar
explosions, known as supernovae, but they have always seen them after
the fireworks were well underway.
"For years we have dreamed of seeing a star just as it was exploding,
but actually finding one is a once in a lifetime event," says team
leader Alicia Soderberg, a Hubble and Carnegie-Princeton Fellow at
Princeton University in Princeton, N.J. "This newly born supernova is
going to be the Rosetta stone of supernova studies for years to come."
A typical supernova occurs when the core of a massive star runs out of
nuclear fuel and collapses under its own gravity to form an ultradense
object known as a neutron star. The newborn neutron star compresses and
then rebounds, triggering a shock wave that plows through the star's
gaseous outer layers and blows the star to smithereens. Astronomers
thought for nearly four decades that this shock "break-out" will produce
bright X-ray emission lasting a few minutes.
But until this discovery, astronomers have never observed this signal.
Instead, they have observed supernovae brightening days or weeks later,
when the expanding shell of debris is energized by the decay of
radioactive elements forged in the explosion. "Seeing the shock
break-out in X-rays can give a direct view of the exploding star in the
last minutes of its life and also provide a signpost to which
astronomers can quickly point their telescopes to watch the explosion
unfold," says Edo Berger, a Carnegie-Princeton Fellow at Princeton
University.
Soderberg's discovery of the first shock breakout can be attributed to
luck and Swift's unique design. On January 9, 2008, Soderberg and Berger
were using Swift to observe a supernova known as SN 2007uy in the spiral
galaxy NGC 2770, located 90 million light-years from Earth in the
constellation Lynx. At 9:33 a.m. EST they spotted an extremely bright
5-minute X-ray outburst in NGC 2770. They quickly recognized that the
X-rays were coming from another location in the same galaxy.
In a paper appearing in the May 22 Nature, Soderberg and 38 colleagues
show that the energy and pattern of the X-ray outburst is consistent
with a shock wave bursting through the surface of the progenitor star.
This marks the birth of the supernova now known as SN 2008D.
Although astronomers were lucky that Swift was observing NGC 2770 just
at the moment when SN 2008D's shock wave was blowing up the star, Swift
is well equipped to study such an event because of its multiple
instruments observing in gamma rays, X-rays, and ultraviolet light. "It
was a gift of nature for Swift to be observing that patch of sky when
the supernova exploded. But thanks to Swift's flexibility, we have been
able to trace its evolution in detail every day since," says Swift lead
scientist Neil Gehrels of NASA's Goddard Space Flight Center in
Greenbelt, Md.
Due to the significance of the X-ray outburst, Soderberg immediately
mounted an international observing campaign to study SN 2008D.
Observations were made with major telescopes such as the Hubble Space
Telescope, the Chandra X-ray Observatory, the Very Large Array in New
Mexico, the Gemini North telescope in Hawaii, the Keck I telescope in
Hawaii, the 200-inch and 60-inch telescopes at the Palomar Observatory
in California, and the 3.5-meter telescope at the Apache Point
Observatory in New Mexico.
The combined observations helped Soderberg and her colleagues pin down
the energy of the initial X-ray outburst, which will help theorists
better understand supernovae. The observations also show that SN 2008D
is an ordinary Type Ibc supernova, which occurs when a massive, compact
star explodes. Significantly, radio and X-ray observations found no
evidence that a jet played a role in the explosion, ruling out a rare
type of stellar explosion known as a gamma-ray burst.
"This was a typical supernova," says Swift team member Stefan Immler of
NASA Goddard. "The significance is not the explosion itself, but the
fact that we were able to see the star blow up in real time, which gives
us unprecedented insight into the explosion process."
For related images to this story, please visit on the Web:
http://www.nasa.gov/centers/goddard/news/topstory/2008/swift_supernova.html
For more information on Swift, please visit:
http://www.nasa.gov/mission_pages/swift/main/index.html