Pandora of as seen in the movie Avatar |
Alpha Centauri A is one of the stars of
the Alpha Centauri star system, located at a distance of 4.37 light years away
from the Earth. The stars Alpha Centauri A and Alpha Centauri B are orbiting
each other, getting close as Saturn to the sun and getting far as Pluto and sun.
Many planetary scientists proposed the possibility of a gas giant like Polyphemus
is less, because the gravitational pull of the two stars will kick out such a
large planet out of the system.
Therefore a terrestrial planet orbiting a star was expected to be found.
In 2009
computer simulations showed that a planet might have been able to form within a
distance of 1.1 AU (160 million km) of Alpha Centauri B, and that the
orbit of that planet may remain stable for at least 250 million years. Proving
close to that simulation, a team of European scientists of the ESO (European
Southern Observatory) have found confirmable
evidence of an earth-like planet orbiting around Alpha Centauri B star. Then, the existence of Pandora is coming quite possible due to this
discovery which was revealed on 16th October 2012.
Artist's Conception of the newly discovered planet CREDIT : ESO\L . Calcada |
This is the closest exoplanet to Earth which has been ever
discovered. Also it is the least massive exoplanet that was discovered orbiting
a sun-like star. This planet is named as
Alpha Centauri Bb and it has a 1.13
times the mass of the earth. But don’t expect liquid water on it. Because this
one orbits around its star at a stunning distance about 3.6 million miles (6
million kilometers or 0.04 AU) and orbits a round in just 3.6 days. That means its orbit is
too much closer to the star than the mercury’s orbit to our sun. The
gravitational force of the Alpha Centauri A has pulled the planet much forward
to the star. Because of that it has a heat-blasted surface of 1200 0C
and it may be covered with molten rock or lava. (Watch the video about it by ESO.)
Although closest to the earth, it took a long time to
discover this planet after the discoveries of more than 840 exoplanets. Because
the star system is much complex to discover clues of an exoplanet. After high
accurate measurements this discovery was made using the radial velocity
technique with HARPS (High Accuracy Radial velocity Planet Searcher) at La Silla Observatory, Chile. The technique used is to
measure the Doppler shifts in the spectrum of a star due to the gravitational
pull of a planet. The highest precision of the HARPS instrument, magnitude of
51 centimeters per second was reported to make this important discovery. More than 450
HARPS measurements taken over four years of observing have been needed to
detect the planet's signal.
Top left : Dome of the telescope Top right: The relescope Lower: The HARPS Spectrograph |
The
discovery team is composed of Xavier Dumusque (Observatoire de Genève,
Switzerland; Centro de Astrofisica da Universidade do Porto, Portugal),
Francesco Pepe (Observatoire de Genève), Christophe Lovis (Observatoire de
Genève), Damien Ségransan (Observatoire de Genève), Johannes Sahlmann
(Observatoire de Genève), Willy Benz (Universität Bern, Switzerland), François
Bouchy (Observatoire de Genève; Institut d’Astrophysique de Paris, France),
Michel Mayor (Observatoire de Genève), Didier Queloz (Observatoire de Genève),
Nuno Santos (Centro de Astrofisica da Universidade do Porto) and Stéphane Udry
(Observatoire de Genève).
Many low-mass planets
like Alpha Centauri Bb are in a system of two, three or even up to six, seven
planets. So, this has raised the
possibility of a planet in the habitable zone or goldilock zone of Alpha
Centauri B, located at 65 million miles from the star that a planet would take
around 200 days to orbit. Many astronomers say there are more planets in this
system definitely. Dr. Dumusque has said that it would need 8 to 10 years to
find a planet at 200 days by using this instrument.
So this discovery makes a landmark in the goal of exoplanet
hunters, finding an earth-like exoplanet, the so-called Earth 2.0. With the advancement of the technology in the
next decade, exoplanet hunters would discover a Pandora, orbiting around one of a star or both. Even without Polyphemus,
it would be a science fiction Pandora becoming a fact. Some scientists have
proposed to send a probe to Alpha Centauri system even it would take 100 years
or more time to reach. It seems like our
closest neighbor star system has much more mysteries than we anticipated.
The position of Pandora as depicted in the Avatar game. |