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By Deborah Zabarenko
WASHINGTON
(Reuters) - Scientists using a massive telescope in Australia
have taken the pulse of a sun-like star to get clues to
what might happen to our Sun several billion years from
now.
Astronomers
already have a fairly good idea about what will happen to
the Sun in the distant future: it will expand and eventually
extend out beyond Earth's orbit. But this is from computer
models, not direct observation, and it will not occur for
many billions of years.
The
work done by an international team using the Anglo-Australian
Telescope looked directly at the star Beta Hydri for five
nights last June, and found it had the same kind of pulse
-- an oscillation of material on its surface -- as the Sun
does.
But
while the Sun is only about 4.5 billion years old, scientists
estimate Beta Hydrus is about 7 billion years old, a sort
of older sibling to the star at the heart of our solar system.
Just
as a child might look to an older sister to guess at what
she might become, scientists might look at Beta Hydri to
see what the Sun's more immediate future might be.
The
guessing is not just skin-deep. By timing the surface oscillations,
astronomers might be able to find out more about what is
at the center of Beta Hydri.
The
same technique has been used for the Sun, but it is much
easier to take the Sun's pulse, since it is so much closer
to Earth. The Sun is about 93 million miles (150 million
km)from Earth, whereas Beta Hydri is 24 light years away,
which is close in cosmic terms but still quite far for an
Earth-based telescope.
A light
year is about 6 trillion miles (10 trillion km), the distance
light travels in a year.
"Using
incredibly precise instrumentation, they've been able to
detect very similar oscillations'' on Beta Hydri, said Morris
Aizenman of the National Science Foundation (news - web
sites), which helped fund the research.
"Magic
Bullet''
"It's
sort of like that magic bullet that allows you to see inside
the star,'' Aizenman said in a telephone interview.
The
next step, he said, was to continue the measurements and
try to get more precise data and to look at other stars
as well.
"Beta
Hydri gives us a good idea of what the Sun will look like
in a few billion years,'' Tim Bedding of the University
of Sydney said in a statement.
Bedding,
Paul Butler of the Carnegie Institution of Washington and
colleagues from the United States, Australia, Denmark and
Switzerland studied the star with the Anglo-Australian Telescope
at Siding Spring, Australia, about halfway between Melbourne
and Brisbane.
Scientists
discovered the Sun's surface oscillations in 1979 and have
been looking for the same pulse on other stars. Beta Hydri
is about the same mass and temperature as the Sun so it
was a good candidate for comparison.
The
Sun's pulse is fast, with tiny oscillations coming as frequently
as every five minutes; with a slightly older star like Beta
Hydri, astronomers expected a slower pulse and they got
it: the guess was between 15 and 20 minutes, with the actual
observation was 17 minutes.
"Detecting
these seismic waves on Beta Hydri is like feeling the pulse
of the star,'' Butler said in a statement. "Just as a person's
pulse reveals information about the heart, these oscillations
allow us to peer deep into the center of the star to tell
us about conditions there.''
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