Artist's view of the COROT satellite, consisting of a 27-centimetre space telescope. A mission led by CNES with ESA participation, it was launched in December 2006. COROT uses its telescope to monitor closely the changes in a star’s brightness that comes from a planet crossing in front of it.
Credit: CNES - D. Ducros
PARIS: Ten new exoplanets have been discovered by the European satellite CoRoT, including seven hot Jupiters, a planet smaller than Saturn and a system of two Neptune-like objects orbiting the same star.
Confirmed via ground-based observations, the exoplanets exhibit a wide variety of masses, densities, orbital parameters and other properties, highlighting the broad diversity of planets around stars other than our Sun.
The results have been reported at the Second CoRoT Symposium held this week in Marseille, France.
"Ever since the early days of exoplanet astronomy, we've been amazed by the variety of planets that have been discovered: gaseous giants larger than Jupiter and smaller, rocky bodies, down to masses comparable to the Earth's," said Malcolm Fridlund, the European Space Agency's (ESA) project scientist for CoRoT.
565 exoplanets so far
When the hunt for planets around stars other than the Sun began over 15 years ago, achieving a detection was the primary goal of the field.
After almost two decades of research and the discovery of several hundred exoplanets, the focus has now shifted towards a more analytical approach in order to pin down the characteristics of a large number of planets.
CoRoT is the first space mission dedicated to the search for planets outside our Solar System's realm and has so far discovered 26 new exoplanets, bringing the total known number to 565.
A 'zoo' of exoplanets
The new results highlight the range of the properties observed within the 'zoo' of exoplanets within highly diverse systems that have a wide range of orbital periods.
About 70 systems in which multiple planets have been detected. "The new set of ten planets that we announce today are no exception, exhibiting as they do a rich list of very interesting properties," said Fridlund.
Of the most recent additions to the CoRoT family, seven are so-called 'hot Jupiters', one is smaller than Saturn (CoRoT-22b) and the other two (CoRot-24b and CoRot-24c), with masses similar to that of Neptune, have been found orbiting the same star.
The densities of these planets, which are all gaseous, span a wide range, from values similar to that of Saturn, the least dense planet in the Solar System, to higher values comparable to the density of Mars.
Understanding planet formation
The host stars also exhibit rather mixed properties, ranging from a 10 thousand million year old star - twice as old as the Sun - in the case of CoRoT-17b, to a rather young (about 600 million years) counterpart, in the case of CoRoT-18b.
Observing planetary systems with such different ages is particularly useful when testing different scenarios of planet formation and evolution. Two of the planets (CoRoT-16b and CoRoT-20b) lie on highly elongated orbits, and explaining their survival on such orbits represents a challenge from the dynamical point of view.
The double system of Neptune-like bodies is rather peculiar, and it will be monitored in the future to determine if it harbours other planets as well.
