Andrew Yee[_1_]
August 6th 07, 07:59 PM
Office of Public Information
Eberly College of Science
Pennsylvania State University
University Park, Pennsylvania
CONTACTS:
Alex Wolszczan, (+1) 814-863-1756
Lawrence Ramsey, (+1)814-865-0410
Barbara Kennedy (PIO), (+1) 814-863-4682
2 August 2007
Planet Orbiting a Giant Red Star Discovered with Hobby-Eberly Telescope
A planet orbiting a giant red star has been discovered by an astronomy team
led by Penn State's Alex Wolszczan, who in 1992 discovered the first planets
ever found outside our solar system. The new discovery is helping
astronomers to understand what will happen to the planets in our solar
system when our Sun becomes a red-giant star, expanding so much that its
surface will reach as far as Earth's orbit. The star is 2 times more massive
and 10 times larger than the Sun. The new planet circles the giant star
every 360 days and is located about 300 light years from Earth, in the
constellation Perseus. A paper describing the discovery will be published in
a November 2007 issue of the Astrophysical Journal.
The discovery resulted from an ongoing effort that the research team began
three years ago to find Jupiter-mass planets around red-giant stars that are
typically farther from Earth than those included in most other planet
searches. "After astronomers have spent more than 10 years searching for
planets around Sun-like stars and discovering over 250 planets elsewhere in
our galactic neighborhood, we still do not know whether our solar system's
properties, including life-supporting conditions on our planet, are typical
or exceptional among solar systems throughout the Galaxy," Wolszczan says.
"The picture for now, based on the searches for planets around stars like
our Sun, is that our planetary system appears to be unusual in a number of
ways."
"This planet is the first one discovered by Penn State astronomers with the
Hobby-Eberly Telescope, and it is in one of the most distant of the ten
published solar systems discovered around red-giant stars," comments
Lawrence Ramsey, a member of the discovery team and the head of the
Department of Astronomy and Astrophysics at Penn State. Ramsey is a leader
in the conception, design, construction, and operation of the Hobby-Eberly
Telescope. "We are now becoming serious participants in planetary searches
and planetary astronomy using the Hobby-Eberly Telescope," he says.
Astronomers now are branching out with different strategies for searching
for planets, with the hope of more quickly detecting life elsewhere in the
universe, of discovering all the possible kinds of solar systems, and of
learning how they form around different kinds of stars. Wolszczan's team
used one of these new strategies -- searching for planets around giant
stars, which have evolved to a later stage of life than our Sun's.
"We have compiled a catalog of nearly a thousand giant stars that are
candidates for hosting solar systems," Wolszczan says. Because the method
for discovering planets involves repeated measurements of their
gravitational effect on the star they circle, and because planets around red
giants can take years to make one orbit around the star, the research team
is just now beginning to reap discoveries from years of systematic
observations. "It took us 3 years to gather enough data on over 300 stars to
start identifying those that are good candidates for having planetary
companions," Wolszczan said. "This planet is just the first of a number of
planet discoveries that this research program is likely to produce."
This research is a collaboration between astronomers at Penn State, Nicholas
Copernicus University in Poland, the McDonald Observatory, and the
California Institute of Technology. "One important aspect of this work is
that it marks the debut of a research group in Poland, led by Dr. Andrzej
Niedzielski, which has become a serious contributor to discoveries in
extra-solar planetary astronomy," Wolszczan said.
One reason for studying solar systems that include red-giant stars is that
they help astronomers to understand more about the future of our own solar
system -- as family photos can give children an idea of what they might look
like when they are the age of their grandparents. "Our Sun probably will
make the Earth unhabitable in about 2 billion years because it will get
hotter and hotter as it evolves on its way to becoming a red giant about 5
billion years from now," Wolszczan says. As the star swells up, transforming
itself into a red giant, it affects the orbits of its planets and the
dynamics of the whole planetary system, causing such changes as orbit
crossings, planet collisions, and the formation of new planets out of the
debris of those collisions. "When our Sun becomes a red giant, Earth and the
other inner planets very likely will dive into it and disappear," Wolszczan
says.
Another motivation for studying red-giant stars is to understand how their
habitable zones move farther out as the star's radiating surface becomes
bigger. Based on how long it took for life to develop on Earth, scientists
speculate that there is more than enough time during a star's giant phase
for life to get a start somewhere in the evolving habitable zones. "In our
solar system, places like Europa -- a satellite of Jupiter that now is
covered by a thick layer of water ice -- might warm up enough to support
life for more than a billion years or so, over the time when our Sun begins
to evolve into a red giant, making life on Earth impossible," Wolszczan
said.
The method the astronomers use to discover planets is to observe candidate
stars, repeatedly measuring their space velocity using the Doppler effect --
the changes in the star's light spectrum that result from its being pulled
alternately toward and away from Earth by the gravity of an orbiting planet.
"When we detect a significant difference in a star's velocity over a month
or two, we then start observing that star more frequently," Wolszczan says.
"In this paper, the velocity of the star changed by about 50 meters per
second (about 100 miles per hour) between our first and second observations,
so we observed that star more frequently and we found a clearly repeatable
effect, indicating the presence of a planet." A star and its orbiting planet
move around the center-of-mass of the whole system, so the star alternately
approaches and recedes from Earth periodically. "When the star gets closer
to us, its light becomes a little bit bluer and when it recedes from us, its
light becomes redder, and we can measure that effect to deduce the presence
of planets," Wolszczan explains.
Searching for planets around giant stars also is a clever way to learn about
the formation of planets around stars more massive than our Sun. Because
massive stars are so hot when they are in the phase of life of our Sun,
astronomers have not been able to detect enough of their spectral lines to
use the Doppler-spectroscopy method of finding planets. However, these stars
become cooler as they evolve into giants, at which point the spectral-line
observations needed for Doppler detection of planets become possible. "We
want to know how often do planets form around stars that were more massive
than our Sun," Wolszczan said. "Obviously, the more solar systems around red
giants we discover and study, the better chance we have to really understand
the big picture of planet formation."
Another reason astronomers are trying to discover planets around different
kinds of stars at different stages of stellar evolution is to find out how
different kinds of planetary systems change when their stars become red
giants and how they ultimately end their lives as burnt-out, shrunken
white-dwarfs.
"We really are at the very beginning of this effort and it is going to take
time to get a consistent picture of planetary formation and evolution,"
Wolszczan says. "The more we learn, the greater the chance will be that
sooner or later we will discover how ordinary or extraordinary is our home
-- the Earth's solar system."
This research received financial support from NASA's Jet Propulsion
Laboratory, Penn State's NASA-funded Astrobiology Program, the Polish
Ministry of Science and Higher Education, and private donors.
ABOUT THE HOBBY-EBERLY TELESCOPE
The William P. Hobby-Robert E. Eberly Telescope is one of the largest and
most powerful telescopes in the world. It was conceived by Lawrence Ramsey,
department head and professor of astronomy and astrophysics at Penn State,
and Daniel W. Weedman, formerly a professor of astronomy and astrophysics at
Penn State. The Hobby-Eberly Telescope is located in a remote area of West
Texas at the McDonald Observatory, which has the darkest skies of any major
observatory in the continental United States. The namesakes of the
Hobby-Eberly Telescope are William P. Hobby, the former Lieutenant Governor
of Texas, and Robert E. Eberly of Pennsylvania, an industrialist and
philanthropist. The Hobby-Eberly Telescope is a joint project of The
University of Texas at Austin, Penn State University, Stanford University,
Ludwig-Maximilians-Universitat Munchen and Georg-August-Unversitat
Gottingen.
[NOTE: Images supporting this release are available at
http://www.science.psu.edu/alert/Wolszczan8-2007.htm ]
Eberly College of Science
Pennsylvania State University
University Park, Pennsylvania
CONTACTS:
Alex Wolszczan, (+1) 814-863-1756
Lawrence Ramsey, (+1)814-865-0410
Barbara Kennedy (PIO), (+1) 814-863-4682
2 August 2007
Planet Orbiting a Giant Red Star Discovered with Hobby-Eberly Telescope
A planet orbiting a giant red star has been discovered by an astronomy team
led by Penn State's Alex Wolszczan, who in 1992 discovered the first planets
ever found outside our solar system. The new discovery is helping
astronomers to understand what will happen to the planets in our solar
system when our Sun becomes a red-giant star, expanding so much that its
surface will reach as far as Earth's orbit. The star is 2 times more massive
and 10 times larger than the Sun. The new planet circles the giant star
every 360 days and is located about 300 light years from Earth, in the
constellation Perseus. A paper describing the discovery will be published in
a November 2007 issue of the Astrophysical Journal.
The discovery resulted from an ongoing effort that the research team began
three years ago to find Jupiter-mass planets around red-giant stars that are
typically farther from Earth than those included in most other planet
searches. "After astronomers have spent more than 10 years searching for
planets around Sun-like stars and discovering over 250 planets elsewhere in
our galactic neighborhood, we still do not know whether our solar system's
properties, including life-supporting conditions on our planet, are typical
or exceptional among solar systems throughout the Galaxy," Wolszczan says.
"The picture for now, based on the searches for planets around stars like
our Sun, is that our planetary system appears to be unusual in a number of
ways."
"This planet is the first one discovered by Penn State astronomers with the
Hobby-Eberly Telescope, and it is in one of the most distant of the ten
published solar systems discovered around red-giant stars," comments
Lawrence Ramsey, a member of the discovery team and the head of the
Department of Astronomy and Astrophysics at Penn State. Ramsey is a leader
in the conception, design, construction, and operation of the Hobby-Eberly
Telescope. "We are now becoming serious participants in planetary searches
and planetary astronomy using the Hobby-Eberly Telescope," he says.
Astronomers now are branching out with different strategies for searching
for planets, with the hope of more quickly detecting life elsewhere in the
universe, of discovering all the possible kinds of solar systems, and of
learning how they form around different kinds of stars. Wolszczan's team
used one of these new strategies -- searching for planets around giant
stars, which have evolved to a later stage of life than our Sun's.
"We have compiled a catalog of nearly a thousand giant stars that are
candidates for hosting solar systems," Wolszczan says. Because the method
for discovering planets involves repeated measurements of their
gravitational effect on the star they circle, and because planets around red
giants can take years to make one orbit around the star, the research team
is just now beginning to reap discoveries from years of systematic
observations. "It took us 3 years to gather enough data on over 300 stars to
start identifying those that are good candidates for having planetary
companions," Wolszczan said. "This planet is just the first of a number of
planet discoveries that this research program is likely to produce."
This research is a collaboration between astronomers at Penn State, Nicholas
Copernicus University in Poland, the McDonald Observatory, and the
California Institute of Technology. "One important aspect of this work is
that it marks the debut of a research group in Poland, led by Dr. Andrzej
Niedzielski, which has become a serious contributor to discoveries in
extra-solar planetary astronomy," Wolszczan said.
One reason for studying solar systems that include red-giant stars is that
they help astronomers to understand more about the future of our own solar
system -- as family photos can give children an idea of what they might look
like when they are the age of their grandparents. "Our Sun probably will
make the Earth unhabitable in about 2 billion years because it will get
hotter and hotter as it evolves on its way to becoming a red giant about 5
billion years from now," Wolszczan says. As the star swells up, transforming
itself into a red giant, it affects the orbits of its planets and the
dynamics of the whole planetary system, causing such changes as orbit
crossings, planet collisions, and the formation of new planets out of the
debris of those collisions. "When our Sun becomes a red giant, Earth and the
other inner planets very likely will dive into it and disappear," Wolszczan
says.
Another motivation for studying red-giant stars is to understand how their
habitable zones move farther out as the star's radiating surface becomes
bigger. Based on how long it took for life to develop on Earth, scientists
speculate that there is more than enough time during a star's giant phase
for life to get a start somewhere in the evolving habitable zones. "In our
solar system, places like Europa -- a satellite of Jupiter that now is
covered by a thick layer of water ice -- might warm up enough to support
life for more than a billion years or so, over the time when our Sun begins
to evolve into a red giant, making life on Earth impossible," Wolszczan
said.
The method the astronomers use to discover planets is to observe candidate
stars, repeatedly measuring their space velocity using the Doppler effect --
the changes in the star's light spectrum that result from its being pulled
alternately toward and away from Earth by the gravity of an orbiting planet.
"When we detect a significant difference in a star's velocity over a month
or two, we then start observing that star more frequently," Wolszczan says.
"In this paper, the velocity of the star changed by about 50 meters per
second (about 100 miles per hour) between our first and second observations,
so we observed that star more frequently and we found a clearly repeatable
effect, indicating the presence of a planet." A star and its orbiting planet
move around the center-of-mass of the whole system, so the star alternately
approaches and recedes from Earth periodically. "When the star gets closer
to us, its light becomes a little bit bluer and when it recedes from us, its
light becomes redder, and we can measure that effect to deduce the presence
of planets," Wolszczan explains.
Searching for planets around giant stars also is a clever way to learn about
the formation of planets around stars more massive than our Sun. Because
massive stars are so hot when they are in the phase of life of our Sun,
astronomers have not been able to detect enough of their spectral lines to
use the Doppler-spectroscopy method of finding planets. However, these stars
become cooler as they evolve into giants, at which point the spectral-line
observations needed for Doppler detection of planets become possible. "We
want to know how often do planets form around stars that were more massive
than our Sun," Wolszczan said. "Obviously, the more solar systems around red
giants we discover and study, the better chance we have to really understand
the big picture of planet formation."
Another reason astronomers are trying to discover planets around different
kinds of stars at different stages of stellar evolution is to find out how
different kinds of planetary systems change when their stars become red
giants and how they ultimately end their lives as burnt-out, shrunken
white-dwarfs.
"We really are at the very beginning of this effort and it is going to take
time to get a consistent picture of planetary formation and evolution,"
Wolszczan says. "The more we learn, the greater the chance will be that
sooner or later we will discover how ordinary or extraordinary is our home
-- the Earth's solar system."
This research received financial support from NASA's Jet Propulsion
Laboratory, Penn State's NASA-funded Astrobiology Program, the Polish
Ministry of Science and Higher Education, and private donors.
ABOUT THE HOBBY-EBERLY TELESCOPE
The William P. Hobby-Robert E. Eberly Telescope is one of the largest and
most powerful telescopes in the world. It was conceived by Lawrence Ramsey,
department head and professor of astronomy and astrophysics at Penn State,
and Daniel W. Weedman, formerly a professor of astronomy and astrophysics at
Penn State. The Hobby-Eberly Telescope is located in a remote area of West
Texas at the McDonald Observatory, which has the darkest skies of any major
observatory in the continental United States. The namesakes of the
Hobby-Eberly Telescope are William P. Hobby, the former Lieutenant Governor
of Texas, and Robert E. Eberly of Pennsylvania, an industrialist and
philanthropist. The Hobby-Eberly Telescope is a joint project of The
University of Texas at Austin, Penn State University, Stanford University,
Ludwig-Maximilians-Universitat Munchen and Georg-August-Unversitat
Gottingen.
[NOTE: Images supporting this release are available at
http://www.science.psu.edu/alert/Wolszczan8-2007.htm ]