The search for radio signals from alien worlds is expanding to
20,000 star systems that were previously considered poor targets for
intelligent extraterrestrial life, US researchers said Wednesday.
New
scientific data has led the SETI Institute to believe systems orbiting red
dwarfs - dim, long-lived stars that are on average billions of years older than
our sun - are worth investigating.
"This
may be one instance in which older is better," said astronomer Seth
Shostak of
California-based SETI, a private, non-profit organization which stands for Search for Extraterrestrial Intelligence.
California-based SETI, a private, non-profit organization which stands for Search for Extraterrestrial Intelligence.
"Older
solar systems have had more time to produce intelligent species."
The
two-year project involves picking from a list of about 70,000 red dwarfs and
scanning 20,000 of the nearest ones, along with the cosmic bodies that circle
them.
To do this, scientists will use the SETI Institute's Allen
Telescope Array in northern California, a group of 42 antennas that can observe
three stars simultaneously.
"We'll
scrutinize targeted systems over several frequency bands between 1 and 10
GHz," said SETI scientist Gerry Harp.
"Roughly
half of those bands will be at so-called 'magic frequencies' - places on the
radio dial that are directly related to basic mathematical constants," he
added.
"It's
reasonable to speculate that extraterrestrials trying to attract attention
might generate signals at such special frequencies."
For
a long time, scientists ruled out searching around red dwarfs because habitable
zones around the stars are small.
Any
planets orbiting them would be so close that one side would be constantly
facing the star, making one side of the planet very hot and the other quite
cold and dark.
But
more recently, scientists have learned that heat could be transported from the
light side of the planet to the darker side, and that much of the surface could
be amenable to life.
"In
addition, exoplanet data have suggested that somewhere between one sixth and
one half of red dwarf stars have planets in their habitable zones, a percentage
comparable to, and possibly greater than, for Sun-like stars," said the statement.
Experts have been hunting for alien intelligence for six decades, but have not found any evidence yet.
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