COROT surprises a year after launch (Forwarded)

ESA News
http://www.esa.int

20 December 2007

COROT surprises a year after launch

The space-borne telescope, COROT (Convection, Rotation and planetary
Transits), has just completed its first year in orbit. The observatory has
brought in surprises after over 300 days of scientific observations.

Pioneering precision measurement over long periods of time COROT is
observing a large number of stars, up to 12 000, simultaneously, at a very
high precision -- unprecedented in ground-based astronomy. The key to the
high-precision is that the observations can be carried out over very long
periods of time -- up to 150 days. This is being done for the first time
ever.

The satellite measures variations in the light output of these stars down to
one part in a million. This level of precision allows scientists to study
the many ways in which stars vary. The pulsations are caused either due to
unknown physical processes in the stellar interior, or by objects such as
planets passing in front of the stellar surface.

A treasure trove of information for stellar seismology

To date, 30 stars have been observed as part of the study of stellar
seismology, the study of the miniscule changes in light output from a star
caused by acoustic waves travelling through the star. The pattern of the
changes tells us a lot about what is happening deep inside the star. The
stars observed by COROT range from objects similar to our own Sun to older
or more massive stars. The observation period varies between 20 and 150 days
of essentially uninterrupted study.

After a preliminary analysis, the measurements have revealed very exciting
results

Research into solar-type oscillations is one of the mission's key
objectives. Such oscillations have already been found in two stars that are
very similar to our sun -- first in HD49933 and then in HD181420. The
variations are very weak in amplitude and given their short coherence time
(the duration for which a particular wave persists on the stellar surface),
they are very hard to detect and measure.

COROT's discovers its second exoplanet

As a planet passes in front of a star, there is a dip in the light output
from the star, which is detected by COROT. Since many other processes can
mimic the signature observed, to confirm the presence of a planet, a large
confirmation programme with supplementary ground-based observations is
necessary to prove the existence of a planet.

Although COROT observes thousands of light curves, the pace of discovery is
governed by ground-based observations.

In the third sequence of COROT observations, a likely time for the transit
of COROT-exo-2b in front of its star was worked out and an analysis of the
light curve was carried out in real-time to confirm the find. Observations
were carried out simultaneously at the observatory of Haute Provence in
France, and at the European Southern Observatory in Chile, confirming the
existence of the planet and its mass was measured.

COROT-exo-2b orbits a star similar to our Sun, somewhat more massive and
cooler, but more active. It is located about 800 light-years from Earth in
the direction of the constellation Serpens. COROT-exo-2b is a giant planet,
1.4 times larger and 3.5 times more massive than Jupiter. Its average
density of 1.5 grams per cubic centimetre is also somewhat higher than
Jupiter's. This massive planet orbits its star in a little less than two
days from a distance of about six times the stellar radius.

"Christmas is early this year," for ESA's COROT Project Scientist, Malcolm
Fridlund. "The release of the first data set has already had the science
team working hard. The quality of the data is fantastic and the results will
change both, how we see exoplanets and how we understand stars."

Notes for editors:

During the spring of 2007, COROT discovered its first exoplanet, named
COROT-exo-1b.

On 10 December 2007, the first set of data obtained by COROT was released to
the Co-Investigators of the mission. These scientists hail from the member
states of the COROT consortium (ESA, Austria, Belgium, Brazil, Germany, and
Spain). The actual analysis of large amounts of data has just begun and is
expected to speed-up with the release of the next data segment in February
2008.

In the data obtained, many light curves show signs of exoplanets in transit
and are being followed-up from ground. Within this list of objects which is
growing by the day, two candidates stand out as particularly interesting.
One planet is half the size of Saturn, and another is the size of Jupiter,
but with a very unusual density.

The discovery of COROT-exo-1b and COROT-exo-2b is described in three
scientific papers that will be submitted to scientific journals in the next
few days.

COROT has observed four regions so far:

* One zone in the direction of the constellation of the Unicorn (Monoceros)
for 60 days
* Two regions in the opposite direction on the sky, towards the
constellation of the Snake's tail (Serpens Cauda) -- one short for 26 days
and one long for 150 days.
* A new region in the direction of the Unicorn, where COROT will remain for
at least 150 days

COROT was launched by a Soyuz rocket from the Baikonour cosmodrome in
Kazakhstan on 27 December 2006. Settled in its almost-circular polar orbit
ranging between 895 and 906 km above Earth's surface, the spacecraft was
powered on 2 January 2007 and started its science observations on 3 February
this year.

COROT is a CNES project with ESA participation. The other major partners in
this mission are Austria, Belgium, Brazil, Germany and Spain.

For more information:

Malcolm Fridlund, ESA COROT Project Scientist
Email: Malcolm.Fridlund @ esa.int

[NOTE: Images supporting this release are available at
http://www.esa.int/esaCP/SEMF0C2MDAF_index_1.html ]