Stars,
including the sun, experience sound waves that zip around inside them
and cause tiny rhythmic fluctuations in their brightness. By studying
these variations, scientists can better understand the interiors of
stars— an emerging scientific field known as asteroseismology that is
akin to…
A team of researchers has devised a way to measure the internal properties of stars -- a method that …
By analyzing sonic vibrations in a distant sunlike star, astronomers
might have calculated exactly how fast the star spins and how much a
nearby giant alien planet weighs.
Stars, including the sun,
experience sound waves that zip around inside them and cause tiny
rhythmic fluctuations in their brightness. By studying these variations,
scientists can better understand the interiors of stars— an emerging
scientific field known as asteroseismology that is akin to seismology on
Earth, which helps geologists yield insights into the innards of this
planet.
Scientists used the COROT satellite to analyze the sunlike star HD
52265, located more than 90 light-years from Earth in the constellation
Monoceros, the Unicorn. The star, which has a mass about 1.2 times that
of the sun and a diameter 1.3 times greater than the sun's, is about 2.1
billion to 2.7 billion years old. [The Strangest Alien Planets (Gallery)]
Repeated wobbles in the movements of HD 52265 suggested a giant
planet's gravitational pull was tugging on it, which astronomers dubbed
HD 52265b. The magnitude of the wobbles suggested the planet had a mass
at least 1.09 times that of Jupiter — scientists could not give a more
precise figure based on the wobbles alone.
The oscillations in brightness that the researchers investigated are
linked to ripples in that star that are, in turn, based in part on its
rate of rotation. The scientists calculated HD 52265's interior
completes a revolution every 12 days, meaning it revolves some 2.3 times
faster than the sun.
"Knowing the rotation of stars is important to understand stellar
activity cycles," said Laurent Gizon, an astrophysicist at the Max
Planck Institute for Solar System Research in Germany and the study's
lead author. "Magnetic fields in stars like the sun are maintained by
rotation and convection."
Discovering the manner in which the star HD 52265 rotates also provides
clues about how the planet HD 52265b is oriented toward it, assuming
the star's equator is lined up with the planet's, as is typically the
case in Earth's solar system. When these data are combined with the
information about the magnitude of the wobbles the planet exerts on its
star, the mass of world is about 1.85 times the mass of Jupiter, the
researchers calculated.
"Asteroseismology is a very powerful technique to fully characterize exoplanets," Gizon said.
In the future, the European Space Agency's PLATO mission could use asteroseismology to analyze a multitude of stars and planets.
"The decision on the selection of the mission is expected at the beginning of 2014," Gizon said.
The scientists detailed their findings online July 29 in the journal Proceedings of the National Academy. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.
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