The unanticipated level of accuracy of this raw data shows that COROT will be able to see rocky planets - perhaps even as small as Earth - and possibly provide an indication of their chemical composition.
COROT, a CNES project with ESA participation, is a mission with a dual goal. It is the first space mission dedicated entirely to the search of extra-solar planets. It provides a wide-field survey of planets like our own at an unprecedented level of accuracy. It is also making the most comprehensive study ever of the interior of stars other than our Sun. Both objectives are achieved by analysing the behaviour of light emitted by a target star.
An exoplanet is detected by COROT due to a sudden decrease in the intensity of light or the ‘light curve’ of a parent star when a planet transits in front of it.
The study of stellar interiors – or ‘asteroseismology’ – is carried out by analysing the oscillations in the light curve of the star. The oscillations are created due to mechanical waves propagating in the star itself and they give a clue to the structure of its interior.
COROT’s strength lies in the continued observation of the same targets in a given area of the sky. The observations have been on since the science operations began, 60 days ago. Another strong point is the accuracy with which it measures the variations in the luminosity of the star.
The first planet detected by COROT, now named ‘COROT-Exo-1b’, is a very hot gas giant, with a radius equal to 1.78 times that of Jupiter. It orbits a yellow dwarf star similar to our Sun with a period of about 1.5 days. ‘COROT-Exo-1b’ is situated roughly 1500 light years from us, in the direction of the constellation Unicorn (Monoceros). Coordinated spectroscopic observations from the ground have also allowed the determination of the mass of the planet, equivalent to about 1.3 Jupiter masses.
The scientific evaluation of the results that are streaming in will take some time. “The data we are presenting today is still raw but exceptional,” says Malcolm Fridlund, COROT Project Scientist for ESA. “It shows that the on-board systems are working better than expected in some cases - up to ten times the expectation before launch. This will have an enormous impact on the results of the mission.”
All the sources of noise and disturbance have not yet been taken into account in the data. This first exoplanet was detected with an error of only five parts out of 100 000 during one hour of observation. When all the corrections are applied to the light curves, the error will be reduced to only one part out of 100 000.
As a consequence, small planets down to the size of our Earth – three times smaller than initially thought possible - will be in the grasp of COROT. The satellite may also be able, in specific circumstances, to detect subtle variations in the stellar light reflected by the planet itself. This would give an indication of its chemical composition.
The quality of the asteroseismological data is equally impressive. Excellent ‘starquake’ data were obtained during the first 60 days of observations, with a margin of error of less than one part per million.
COROT observed a bright Sun-like star continuously for 50 days, showing large, unexpected luminosity variations on time scales of a few days. This may be related to the star’s magnetic activity.
The accuracy of these measurements was truly outstanding: with an error of five parts out of 100 000 in one minute (corresponding to one part per million over four minutes), COROT has already reached the maximum performance for a telescope of its size.
The preliminary analysis of the oscillations in stellar luminosity clearly shows the seismic signature typical of a Sun-like star. This analysis will eventually help scientists understand the star’s internal structure and age.
“COROT, a joint endeavour between France, Europe and Brazil under the leadership of CNES, was certainly born under a lucky star,” concluded Fridlund. “After a perfect launch, and a faster-than-expected start of its science operations, we have been eagerly awaiting its data. Now, having seen its quality, we can expect great discoveries in the future.”
Source: ESA
Related stories:
Venus Express searching for life – on Earth
(PhysOrg.com) -- Scientists using ESA’s Venus Express are trying to observe whether Earth is habitable. Silly, you might think, when we know that Earth is richly stocked with life. In fact, far from being a pointless exercise, Venus Express is paving the way for an exciting new era in astronomy.
COROT's new find orbits Sun-like star
A team of European scientists working with COROT have discovered an exoplanet orbiting a star slightly more massive than the Sun. After just 555 days in orbit, the mission has now observed more than 50 000 stars and is adding significantly to our knowledge of the fundamental workings of stars.
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.
Boring Star May Mean Livelier Planet, Astronomer Says
“Boring” light from red dwarf star Gliese 581 means better odds for extraterrestrial life in that planetary system, according to University of British Columbia astronomer Jaymie Matthews.
Corot sees first light
In the night between 17 and 18 January 2007, the protective cover of the COROT telescope has been successfully opened, and COROT has seen for the first time light coming from stars.
Europe looks forward to COROT launch
On 27 December, COROT is to be launched into space on a unique astronomy mission: its twin goals are to detect exoplanets orbiting around other stars and to probe the mysteries of stellar interiors as never before. COROT is a French national space agency (CNES)-led mission to which the European Space Agency and European partners are adding a particularly strong international flavour.
COROT and the new chapter of planetary searches
The launch of COROT on 21 December 2006 is a long awaited event in the quest to find planets beyond our Solar System. Searching from above the Earth's atmosphere, COROT – the CNES project with ESA participation - will be the first space mission specifically dedicated to the search for extrasolar planets.
Europe goes searching for rocky planets
The COROT space telescope is proceeding smoothly towards its launch in December 2006. Once in orbit, COROT will become the first spacecraft devoted to the search for rocky planets, similar to our own Earth.
