New solar twin could shed light on another Earth
April 3, 2006
ANU (Australian National University) astronomers
have discovered a nearby solar twin which may shed light on the search for
planets that are similar to Earth and that may even support life. HD98618 is
only the second star found so far that is almost identical to the Sun in age,
size, temperature and chemistry, according to the researchers Dr Jorge Meléndez,
Ms Katie Dodds-Eden and Mr José Robles, from the Research School of Astronomy
and Astrophysics.
“This solar twin doesn’t only have the same
mass as the Sun, it was also formed with the same ‘chemical recipe’. So this
star was equipped in the same way as the Sun to form Earth-like planets,” Mr
Robles said.
“Hopefully, as new planet finding techniques are developed and refined,
astronomers will find whether HD98618 hosts terrestrial planets, which may even
contain life.”
HD98618 lies a mere 126 light-years away in the northern constellation of Ursa
Major (the ‘Big Dipper’). It is bright enough to see in binoculars, but only
in the Northern Hemisphere.
The researchers believe that HD98618 is about four billion years-old, about 10
per cent younger than our own Sun. Its chemical properties are almost identical
to the Sun and to the other closest Sun twin, a star known as 18 Scorpii, which
was discovered a decade ago.
“It means that hypothetical terrestrial planets around this solar twin may
have had enough time to develop some kind of complex life, assuming the
time-scale for complex life formation is similar to Earth’s,” Dr Meléndez
said.
The team says that focused observations of the two stars by planet-hunter teams
could reveal or rule out within a few years giant planets, such as our own
Jupiter, around HD98618. “18 Scorpii and HD98618 offer hope to find solar
systems similar to our own in the Universe,” Dr Meléndez said.
The discovery also has implications for research
in other areas. Solar twins are ideal for the absolute calibration of
astronomical measuring instruments. They can provide data useful in modelling
the solar phenomena that may affect climate change, and will help settle the
argument about the uniqueness or otherwise of our Sun and Solar System.
“We had a number of candidates with similar properties to the Sun, but while
we held out hope for each star that it would turn out to be really special, it
was not at all certain to happen. HD 98618 was one of the last of our candidates
to be analysed, so it was quite a surprise when we discovered how it stood out
from the other candidates, together with 18 Scorpii. It was very exciting - I
had to blink twice to be sure I wasn’t imagining it,” Ms Dodds-Eden said.
The researchers made the discovery using the largest telescope in the world, the
10m Keck I telescope on the summit of Hawaii’s dormant Mauna Kea volcano.
Their paper detailing the discovery will be published in Astrophysical
Journal Letters.
SOURCE: Raiders News Update