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 milesfrom 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, 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, which helped fund the research. "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."