Download International Reporter, India 07-24-06 A Glimpse at the Future of Our Sun

International Reporter, India
07-24-06
A Glimpse at the Future of Our Sun
As astronomers increasingly link two telescopes as interferometers to reveal
greater detail of distant stars, a Keck Observatory astronomer is showing the
power of linking three or even more telescopes together.
Astronomer Sam Ragland used Arizona’s Infrared-Optical Telescope Array
(IOTA) of three linked telescopes to obtain unprecedented detail of old red giant
stars that represent the eventual fate of the Sun.
Surprisingly, he found that nearly a third of the red giants he surveyed were not
uniformly bright across their face, but were patchy, perhaps indicating large spots
or clouds analogous to sunspots, shock waves generated by pulsating
envelopes, or even planets.
“The typical belief is that stars have to be symmetric gas balls,” said Ragland, an
interferometer specialist. “But 30 percent of these red giants showed asymmetry,
which has implications for the last stages of stellar evolution, when stars like the
Sun are evolving into planetary nebulae.”
The results obtained by Ragland and his colleagues also prove the feasibility of
linking a trio – or even quintet or sextet – of infrared telescopes to get higher
resolution images in the near-infrared than has been possible before.
“With more than two telescopes, you can explore a totally different kind of
science than could be done with two telescopes,” he said.
“It’s a big step to go from two telescopes to three,” added theoretician Lee Anne
Willson, a coauthor of the study and a professor of physics and astronomy
at Iowa State University in Ames. “With three telescopes you can tell not only
how big the star is, but whether it’s symmetric or asymmetric. With even more
telescopes, you can start to turn that into a picture.”
Ragland, Willson and their colleagues at institutions in the United States and
France, including NASA, reported their observations and conclusions in a paper
recently accepted by The Astrophysical Journal.
Ironically, the IOTA telescope array, operated jointly on Mt. Hopkins by the
Smithsonian Astrophysical Observatory, Harvard University, the University of
Massachusetts, the University of Wyoming, and the Massachusetts Institute of
Technology’s Lincoln Laboratory, was shut down July 1 to save money. The
initial two-telescope interferometer went online in 1993, and the addition of a third
45-centimeter telescope in 2000 created the first optical and infrared
interferometer trio.