NASA'S Kepler Spacecraft Takes Pulse Of Distant Stars
WASHINGTON -- An international cadre of scientists that used data from
NASA's Kepler spacecraft announced Tuesday the detection of stellar
oscillations, or "starquakes," that yield new insights about the size, age and evolution of stars.
The results were presented at a news conference at Aarhus University
in Denmark by scientists representing the Kepler Asteroseismic
Science Consortium (KASC). The team studied thousands of stars
observed by Kepler, releasing what amounts to a roster of some of
humanity's most well-characterized stars.
Analysis of stellar oscillations is similar to how seismologists study
earthquakes to probe the Earth's interior. This branch of science,
called astroseismology, produces measurements of stars the Kepler
science team is anxious to have.
"Using the unparalleled data provided by Kepler, KASC scientists are
quite literally revolutionizing our understanding of stars and their
structures," said Douglas Hudgins, Kepler Program Scientist at NASA
Headquarters in Washington. "What's more, they are doing so at no
cost to the American taxpayer. All the KASC scientists are supported
by research funding from their home countries. It is a perfect
illustration of the tremendous value that our international partners
bring to NASA missions."
In the results presented Tuesday, one oscillating star took center
stage: KIC 11026764 has the most accurately known properties of any
star in the Kepler field. In fact, few stars in the universe are
known to similar accuracy. At an age of 5.94 billion years, it has
grown to a little over twice the diameter of the sun and will
continue to do so as it transforms into a red giant. The oscillations
reveal that this star is powered by hydrogen fusion in a thin shell
around a helium-rich core.
"We are just about to enter a new area in stellar astrophysics," said
Thomas Kallinger, lead author on a study of red giant stars and
postdoctoral fellow at the Universities of British Columbia and
Vienna. "Kepler provides us with data of such good quality that they
will change our view of how stars work in detail."
KASC scientists also reported on the star RR Lyrae. It has been
studied for more than 100 years as the first member of an important
class of stars used to measure cosmological distances. The
brightness, or light wave amplitude, of the star oscillates within a
well-known period of about 13.5 hours. Yet during that period, other
small cyclic changes in amplitude occur -- behavior known as the Blazhko effect.
The effect has puzzled astronomers for decades, but thanks to Kepler
data, scientists may have a clue as to its origin. Kepler
observations revealed an additional oscillation period that had never
been previously detected. The oscillation occurs with a time scale
twice as long as the 13.5-hour period. The Kepler data indicates the
doubling is linked to the Blazhko effect.
"Kepler data ultimately will give us a better understanding of the
future of our sun and the evolution of our galaxy as a whole," said
Daniel Huber, lead author on one of the KASC studies.
Launched in March 2009, Kepler was designed to discover Earth-size
planets orbiting other stars. The spacecraft uses a huge digital
camera, known as a photometer, to continuously monitor the brightness
of more than 150,000 stars in its field of view as it orbits around
the sun. Kepler searches for distant worlds by looking for
"transits," when a planet passes in front of a star, briefly causing
it to dim. The amount of dimming reveals the size of the planet
compared to the size of the star.
For more information about the findings by the KASC scientists, visit:
http://astro.phys.au.dk/KASC/
For more information about the Kepler mission, visit:
http://www.nasa.gov/kepler
Source: NASA
