Andrew Yee[_1_]
January 11th 07, 04:55 PM
McDonald Observatory
University of Texas
Fort Davis, Texas
Contact: Rebecca Johnson
ph: 512-475-6763 fax: 512-471-5060
10 January 2007
Texas Supernova Search Finds Exploding Stars Fast, Follows Up Faster with
Giant Telescope
SEATTLE, Wash. -- Robert Quimby, a post-doctoral researcher at The
University of Texas at Austin, is heading up the Texas Supernova Search --
an effort to detect exploding stars of all types in the fastest way possible
after their explosion, to better understand how they explode and the types
of stars they were prior to the explosion. This information will aid
scientists using supernovae in cosmology studies, including the study of
dark energy.
Quimby is explaining his search technique and results in a talk today at the
207th meeting of the American Astronomical Society in Seattle, Washington.
The search program uses ROTSE IIIb, a robotic telescope located at The
University of Texas at Austin McDonald Observatory in West Texas. The
telescope is one unit of four placed around the world that make up the
Robotic Optical Transient Search Experiment headquartered at The University
of Michigan. Its primary purpose is to quickly track gamma-ray bursts.
However, 30 per cent of the telescope's observing time is also available to
The University of Texas for other studies like Quimby's Texas Supernova
Search, which uses most of that allocation.
The project has some advantages over other supernova searches. The telescope
has an extremely large field of view -- the width of 3.5 full Moons on a
side (3.4 square degrees). Second, this project looks at the same patches of
sky night after night, Quimby says, explaining that most other search
projects don't work this way. His winter/spring targets include three grids,
which cover the Virgo, Ursa Major, and Coma galaxy clusters. Together, these
fields include hundreds of nearby bright galaxies, and thousands of nearby
dwarf galaxies. Finally, ROTSE IIIb shares mountaintop space with one of the
largest optical telescopes in the world, the 9.2-meter Hobby-Eberly
Telescope (HET). When a supernova is found by ROTSE, it can immediately be
followed up in great detail with HET.
Since the fall of 2004, the Texas Supernova Search has found about 30
supernovae.
Quimby explains that while "hundreds of supernovae are found every year" now
by various search groups, the idea behind his project is to try to get the
earliest look at new supernovae. In other words, he says, "not to find the
most supernovae, but to find the best supernovae."
He explains that "when a supernova explodes, the material expands and thins
out. When it fans out, you see deeper into the explosion. Most people
studying supernovae are looking fairly deep" into the expanding debris
cloud.
In contrast, "we look early," he says. This enables him to study the
exploded star's outer layers, before the debris cloud has had much time to
expand.
The benefit of catching supernovae as soon as possible after they explode,
Quimby says, is to get information that is only available by studying the
star's outer layers. This includes information about the progenitor star,
and about the explosion itself.
"There are very few examples of supernovae that have been studied in the
first few days," Quimby says -- less than a dozen. His survey recently
discovered one, known as supernova 2006bp. Quimby says the Texas Supernova
Search found 2006bp about two days after it exploded. (It was independently
reported earlier by amateur astronomer Koichi Itagaki of Yamagata, Japan.)
This early detection is important, because such studies might reveal
differences in supernovae soon after they explode, which at later times look
identical. The great value of supernovae (specifically, type Ia supernovae)
to cosmology research is their uniformity -- astronomers can count on them
to have a certain peak luminosity for a given light curve shape, which
allows them to calculate distance to the supernova (and its host galaxy)
with great confidence. These measurements were integral, for instance, in
the calculations that revealed that the expansion of the universe is
accelerating, and introduced what many call the greatest enigma in science
today -- dark energy.
But what if all supernovae aren't the same? Quimby's search caught one
exploded star that hints of this possibility: supernova 2005hj. Once the
search found this supernova, they began following it as it changed day by
day using the HET. Spectra taken over a period of time showed that the light
output from this supernova changed over time in a way different from the
norm.
"At first, the velocity of the ejecta decreased over time as is typical,"
Quimby says. "But this was followed by about a two-week period of nearly
constant velocities, which is unusual."
Quimby says there are two possible explanations for 2005hj's unusual
behavior. It could be a merger of two white dwarf stars -- the so-called
"double degenerate" model. The second possibility is that it could be a
white dwarf star that tried to explode, but didn't release enough energy. So
it puffed up a bit, then collapsed back onto the star's core, triggering a
second (much larger) explosion. This case is known as a "pulsating delayed
detonation."
The Texas Supernova Search will continue. Quimby hopes to expand the program
to include all four ROTSE telescopes. Besides unit IIIb at McDonald
Observatory, there are ROTSE telescopes in Australia, Turkey, and Namibia.
The Hobby-Eberly Telescope is a joint project of The University of Texas at
Austin, The Pennsylvania State University, Stanford University,
Ludwig-Maximilians-Universit Mchen and Georg-August-Unversit Gtingen.
-- END --
Note to Editors: Robert Quimby can be reached in Seattle this week and
thereafter in Austin at 512-471-7460.
IMAGE CAPTIONS:
[Image 1:
http://mcdonaldobservatory.org/news/gallery/image.php?id=98]
Supernova 2006bp was discovered by the Texas Supernova Search within two
days of its explosion. Credit: Robert Quimby, UT-Austin McDonald
Observatory.
[Image 2:
http://mcdonaldobservatory.org/news/gallery/image.php?id=100]
The Texas Supernova Search is carried out by post-doctoral researcher Robert
Quimby using the ROTSE IIIb telescope at McDonald Observatory. Credit:
Robert Quimby, UT-Austin McDonald Observatory.
[Image 3:
http://mcdonaldobservatory.org/news/gallery/image.php?id=99]
The Robotic Optical Transient Search Experiment has placed telescopes in
four locations on Earth to cover the entire sky in search of gamma-ray
bursts. One of these, ROTSE IIIb, is located at McDonald Observatory. In
addition to its primary mission, the telescope is used for the Texas
Supernova Search. Credit: ROTSE Collaboration.
[Image 4:
http://mcdonaldobservatory.org/news/gallery/image.php?id=36]
The Hobby-Eberly Telescope. Credit: Marty Harris/McDonald Observatory.
University of Texas
Fort Davis, Texas
Contact: Rebecca Johnson
ph: 512-475-6763 fax: 512-471-5060
10 January 2007
Texas Supernova Search Finds Exploding Stars Fast, Follows Up Faster with
Giant Telescope
SEATTLE, Wash. -- Robert Quimby, a post-doctoral researcher at The
University of Texas at Austin, is heading up the Texas Supernova Search --
an effort to detect exploding stars of all types in the fastest way possible
after their explosion, to better understand how they explode and the types
of stars they were prior to the explosion. This information will aid
scientists using supernovae in cosmology studies, including the study of
dark energy.
Quimby is explaining his search technique and results in a talk today at the
207th meeting of the American Astronomical Society in Seattle, Washington.
The search program uses ROTSE IIIb, a robotic telescope located at The
University of Texas at Austin McDonald Observatory in West Texas. The
telescope is one unit of four placed around the world that make up the
Robotic Optical Transient Search Experiment headquartered at The University
of Michigan. Its primary purpose is to quickly track gamma-ray bursts.
However, 30 per cent of the telescope's observing time is also available to
The University of Texas for other studies like Quimby's Texas Supernova
Search, which uses most of that allocation.
The project has some advantages over other supernova searches. The telescope
has an extremely large field of view -- the width of 3.5 full Moons on a
side (3.4 square degrees). Second, this project looks at the same patches of
sky night after night, Quimby says, explaining that most other search
projects don't work this way. His winter/spring targets include three grids,
which cover the Virgo, Ursa Major, and Coma galaxy clusters. Together, these
fields include hundreds of nearby bright galaxies, and thousands of nearby
dwarf galaxies. Finally, ROTSE IIIb shares mountaintop space with one of the
largest optical telescopes in the world, the 9.2-meter Hobby-Eberly
Telescope (HET). When a supernova is found by ROTSE, it can immediately be
followed up in great detail with HET.
Since the fall of 2004, the Texas Supernova Search has found about 30
supernovae.
Quimby explains that while "hundreds of supernovae are found every year" now
by various search groups, the idea behind his project is to try to get the
earliest look at new supernovae. In other words, he says, "not to find the
most supernovae, but to find the best supernovae."
He explains that "when a supernova explodes, the material expands and thins
out. When it fans out, you see deeper into the explosion. Most people
studying supernovae are looking fairly deep" into the expanding debris
cloud.
In contrast, "we look early," he says. This enables him to study the
exploded star's outer layers, before the debris cloud has had much time to
expand.
The benefit of catching supernovae as soon as possible after they explode,
Quimby says, is to get information that is only available by studying the
star's outer layers. This includes information about the progenitor star,
and about the explosion itself.
"There are very few examples of supernovae that have been studied in the
first few days," Quimby says -- less than a dozen. His survey recently
discovered one, known as supernova 2006bp. Quimby says the Texas Supernova
Search found 2006bp about two days after it exploded. (It was independently
reported earlier by amateur astronomer Koichi Itagaki of Yamagata, Japan.)
This early detection is important, because such studies might reveal
differences in supernovae soon after they explode, which at later times look
identical. The great value of supernovae (specifically, type Ia supernovae)
to cosmology research is their uniformity -- astronomers can count on them
to have a certain peak luminosity for a given light curve shape, which
allows them to calculate distance to the supernova (and its host galaxy)
with great confidence. These measurements were integral, for instance, in
the calculations that revealed that the expansion of the universe is
accelerating, and introduced what many call the greatest enigma in science
today -- dark energy.
But what if all supernovae aren't the same? Quimby's search caught one
exploded star that hints of this possibility: supernova 2005hj. Once the
search found this supernova, they began following it as it changed day by
day using the HET. Spectra taken over a period of time showed that the light
output from this supernova changed over time in a way different from the
norm.
"At first, the velocity of the ejecta decreased over time as is typical,"
Quimby says. "But this was followed by about a two-week period of nearly
constant velocities, which is unusual."
Quimby says there are two possible explanations for 2005hj's unusual
behavior. It could be a merger of two white dwarf stars -- the so-called
"double degenerate" model. The second possibility is that it could be a
white dwarf star that tried to explode, but didn't release enough energy. So
it puffed up a bit, then collapsed back onto the star's core, triggering a
second (much larger) explosion. This case is known as a "pulsating delayed
detonation."
The Texas Supernova Search will continue. Quimby hopes to expand the program
to include all four ROTSE telescopes. Besides unit IIIb at McDonald
Observatory, there are ROTSE telescopes in Australia, Turkey, and Namibia.
The Hobby-Eberly Telescope is a joint project of The University of Texas at
Austin, The Pennsylvania State University, Stanford University,
Ludwig-Maximilians-Universit Mchen and Georg-August-Unversit Gtingen.
-- END --
Note to Editors: Robert Quimby can be reached in Seattle this week and
thereafter in Austin at 512-471-7460.
IMAGE CAPTIONS:
[Image 1:
http://mcdonaldobservatory.org/news/gallery/image.php?id=98]
Supernova 2006bp was discovered by the Texas Supernova Search within two
days of its explosion. Credit: Robert Quimby, UT-Austin McDonald
Observatory.
[Image 2:
http://mcdonaldobservatory.org/news/gallery/image.php?id=100]
The Texas Supernova Search is carried out by post-doctoral researcher Robert
Quimby using the ROTSE IIIb telescope at McDonald Observatory. Credit:
Robert Quimby, UT-Austin McDonald Observatory.
[Image 3:
http://mcdonaldobservatory.org/news/gallery/image.php?id=99]
The Robotic Optical Transient Search Experiment has placed telescopes in
four locations on Earth to cover the entire sky in search of gamma-ray
bursts. One of these, ROTSE IIIb, is located at McDonald Observatory. In
addition to its primary mission, the telescope is used for the Texas
Supernova Search. Credit: ROTSE Collaboration.
[Image 4:
http://mcdonaldobservatory.org/news/gallery/image.php?id=36]
The Hobby-Eberly Telescope. Credit: Marty Harris/McDonald Observatory.