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Posted by baalke on September 20, 2007, 11:43 am
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http://www.iastate.edu/~nscentral/news/2007/sep/planet.shtml
September 12, 2007
Contacts:
Steve Kawaler, Physics and Astronomy, (515) 294-9728, sdk@iastate.edu
Roberto Silvotti, INAF-Osservatorio Astronomico di Capodimonte,
+39/331/4063556, silvotti@na.astro.it
Mike Krapfl, News Service, (515) 294-4917, mkrapfl@iastate.edu
Iowa State astronomer helps discover planet that offers clues to
Earth's future
AMES, Iowa -- An international team of astronomers that includes Steve
Kawaler of Iowa State University has announced the first discovery of
a
planet orbiting a star near the end of its life.
The announcement, culminating seven years of research, will be
published
in the Sept. 13 issue of the journal Nature
<http://www.nature.com/nature/journal/v449/n7159/full/
nature06143.html>.
The news provides a preliminary picture of what could be the Earth's
destiny in four to five billion years. That's when the sun will
exhaust
its hydrogen fuel, expand enormously as a red giant and expel its
outer
layers in an explosive helium flash.
The planet discovered by the researchers, "V 391 Pegasi b," has
survived
all those changes to its sun.
The international research team was led by Roberto Silvotti from the
INAF-Osservatorio Astronomico di Capodimonte in Naples, Italy. They
discovered the planet orbiting "V 391 Pegasi," a faint star in the
constellation of Pegasus.
"The exciting thing about finding a planet around this star is that it
indicates that planetary systems can survive the giant phase and the
helium flash of their parent star," said Kawaler, an Iowa State
professor of physics and astronomy. "It bodes well for the survival of
our own Earth in the distant future. Before V 391 Pegasi lost its
outer
regions at the helium flash, the planet orbited the star at about the
same distance that the Earth orbits our sun."
But, Kawaler said, "We shouldn't take too much heart in this -- this
planet is larger than Jupiter, so a smaller planet like the Earth
could
still be vulnerable."
Kawaler helped the 23-member research team make its discovery by
coordinating observations during a 2003 run of the Whole Earth
Telescope. Iowa State is a lead institution in the Whole Earth
Telescope, a worldwide network of cooperating observatories that allow
astronomers to take uninterrupted measurements of variable stars that
change in brightness. The discovery of V 391 Pegasi b was made by
detailed measurements of the clocklike variation of the star caused by
the planet tugging on it.
Kawaler also advanced the project by doing theoretical calculations to
make sure irregularities of the star's orbital motion were caused by
the
orbiting planet.
The astronomers found that at the present time, V 391 Pegasi b has an
orbital distance 1.7 times the medium distance between the Earth and
the
sun. As stars age and reach their red giant phase, they undergo an
enormous expansion (with their volume increasing by a factor of
millions) that can easily reach and engulf their inner planets.
"The same will happen to the sun," Silvotti said. "As far as our
planets
are concerned, we expect Mercury and Venus to disappear in the sun's
envelope, whereas Mars should survive. The fate of the Earth is less
clear because its position is really at the limit: it appears more
likely that the Earth will not survive the red giant expansion of the
sun either, but it is not for sure."
As is the case for almost all planets beyond our solar system, V 391
Pegasi b cannot be seen directly. Silvotti said it took seven years of
observations and calculations to confirm the existence of the planet.
-30-
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