Astronomers
have found a planet whose skies are illuminated by four different suns - the
first known of its type.
The distant
world orbits one pair of stars and has a second stellar pair revolving around
it.
The discovery
was made by volunteers using the Planethunters.orgwebsite along with a team from UK and US
institutes; follow-up observations were made with the Keck Observatory.
Computerised
attempts to find things [in the data] missed this system entirely. That tells
you there are probably more of these that are slipping through our fingers”
Dr Chris LintottOxford University
The planet,
located just under 5,000 light-years away, has been named PH1 after the Planet
Hunters site.
It is thought
to be a "gas giant" slightly larger than Neptune but more than six
times the size of the Earth.
"You
don't have to go back too far before you would have got really good odds
against one of these systems existing," Dr Chris Lintott, from the University
of Oxford, told BBC News.
"All
four stars pulling on it creates a very complicated environment. Yet there it
sits in an apparently stable orbit.
"That's
really confusing, which is one of the things which makes this discovery so fun.
It's absolutely not what we would have expected."
Binary stars
- systems with pairs of stars - are not uncommon. But only a handful of known
exoplanets (planets that circle other stars) have been found to orbit such
binaries. And none of these are known to have another pair of stars circling
them.
Follow-up observations were made with the
Keck facility on Mauna Kea
Asked how
this planet remained in a stable orbit whilst being pulled on by the gravity of
four stars, Dr Lintott said: "There are six other well-established planets
around double stars, and they're all pretty close to those stars.
"So I
think what this is telling us is planets can form in the inner parts of
protoplanetary discs (the torus of dense gas that gives rise to planetary
systems).
"The
planets are forming close in and are able to cling to a stable orbit there.
That probably has implications for how planets form elsewhere."
·
Stares fixedly at a patch corresponding to 1/400th of the sky
·
Looks at more than 155,000 stars
·
Has so far found 2,321 candidate planets
·
Among them are 207 Earth-sized planets, 10 of which are in the
"habitable zone" where liquid water can exis
PH1 was
discovered by two US volunteers using the Planethunters.org website: Kian Jek
of San Francisco and Robert Gagliano from Cottonwood, Arizona.
They spotted
faint dips in light caused by the planet passing in front of its parent stars.
The team of professional astronomers then confirmed the discovery using the
Keck telescopes on Mauna Kea, Hawaii.
Founded in
2010, Planethunters.org aims to harness human pattern recognition to identify
transits in publicly available data gathered by Nasa's Kepler Space Telescope.
Kepler was
launched in March 2009 to search for Earth-like planets orbiting other stars.
Visitors to
the Planet Hunters website have access to randomly selected data from one of
Kepler's target stars.
Volunteers
are asked to draw boxes to mark the locations of visible transits - when a
planet passes in front of its parent star.
Dr Lintott
points out: "Computerised attempts to find things [in the data] missed
this system entirely. That tells you there are probably more of these that are
slipping through our fingers. We've just stuck a load of new data up on
Planethunters.org to help people find the next one."
Searching for
such systems, he said, was "a complicated test to hand a computer",
adding: "We're using human pattern recognition, which can disentangle that
reasonably well to see the important stuff."
Since
December 2010, more than 170,000 members of the public have participated in the
project.
Thanks :
Really GOOD
In PT ~> http://noticias.terra.com.br/ciencia/ultimasnoticias/0,,EI301,00.html
Peole it's
important for the future.
