COROT discovers its first Exoplanet and detects oscillations in a Sun-like star

The research team for spacecraft COROT can today reveal the first discoveries of this major European mission. The satellite has found a very hot exoplanet and provisional estimates indicate it has a very large radius. COROT has also detected its first seismic oscillations in the light curve of a sun-like star. Based on the quality of this initial data, our knowledge of planets outside our own solar system, known as exoplanets, and of the interiors of stars should be vastly improved over the next three years.

The exoplanet, which has been named COROT-exo-1b, orbits around a yellow dwarf star similar to our Sun in about 1.5 days. It is situated roughly 1500 light years from us, in the direction of the constellation of the Unicorn (Monoceros). The oscillating star is of a similar type and located in the same region of the sky, but much nearer to us.

COROT is primarily funded by the French space agency CNES with contributions from the European Space Agency (ESA), Austria, Belgium, Brazil, Germany and Spain. Following its launch on 27 December 2006, the satellite started its first scientific observations on 5 February 2007. The spacecraft is carrying out the first systematic survey of oscillations in stars other than our Sun, which tell us about their interior structure. It is also searching for exoplanets at an unprecedented level of sensitivity bringing us ever closer to the discovery of other habitable worlds.

The satellite has two main advantages over ground-based projects. Firstly, it can observe the same stars continuously, without interruption, for up 150 days (60 days so far). Secondly, its position above the Earth’s atmosphere enables it to measure the brightness variations of stars much more precisely.

Professor Ian Roxburgh, research professor at Queen Mary University of London and ESA representative on the Scientific Council of the mission, explains: ‘The preliminary analysis of the oscillation spectrum of the solar type star is impressive, given that at this stage we are using raw data. As the data quality improves, we anticipate getting oscillation information on a wide range of stars that will enable us to test and improve our understanding of their structure and evolution.’

‘The performances of all components of the satellite and instrument seem as good, and in some cases significantly better, than we expected’, says Dr Suzanne Aigrain, a lecturer at the University of Exeter and member of the CoRoT Exoplanet Science Team. ‘The data analysed so far are preliminary, yet their quality significantly exceed the pre-launch expectations.’

COROT detects planets by looking for transits, small dips in the apparent brightness of a star caused by a planet passing in front of it. While its first planet is large, the quality of the data suggests COROT will be able to identify rocky planets only a few times larger than our own Earth. COROT may also be able to observe variations in the amount of stellar light reflected towards us by planets as they go around their orbits, giving some indication of their atmospheric properties.

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Notes for editors

• For comment on exoplanets
  Dr Suzanne Aigrain - School of Physics, University of Exeter
  Tel: + 44 (0)1392 264089
  Mobile: + 44 (0)7786 245237
  
  
• Sarah Hoyle - Press Officer
  University of Exeter
  Tel: + 44 (0)1392 262062
  Mobile: + 44 (0)7989 446920
  
  
• For comment on astroseismology
  Professor Ian Roxbrough - Astronomy Unit, Queen Mary, University of London
  Tel: + 44 (0)7802 419567
  Or contact via Siân Halkyard
  + 44 (0)207 8827454
  Mobile: + 44 (0)7970 096175
  
  
• For more general comment on COROT
  Dr Malcom Fridlund
  European Space Agency
  Tel: + 31 71 565 4768

About COROT

COROT is the first exoplanet search mission from space, and the first capable of detecting transits of rocky planets round nearby stars. It consists of a 30-centimetre space telescope and was launched on 27 December 2006. COROT will use its telescope to closely monitor the changes in a star’s brightness that are caused by a planet crossing in front of it. 

It will also carry out the first asteroseismic survey of stars of all masses and ages. Asteroseismology consists of measuring the small oscillations in the brightness of the star that are caused by constant seismic tremors inside the star. Astrophysics can use these oscillations to probe the interior structures of stars, just as geologists use Earthquakes to probe the interior of our planets.

COROT is led by the French national space agency, CNES, with contributions from Austria, Brazil, Belgium, Germany, Spain and the European Space Agency (ESA), which provided the optics for the telescope and tested of the telescope and instrument before launch. Prof Roxburgh and Dr Aigrain are among a number of European scientists who joined the mission through ESA’s participation, along with other experts from Denmark, Switzerland and Portugal. The COROT data will become public one year after release to the co-investigators.

Observations with ground-based telescopes are crucial to the success of COROT. Before launch, the potential planet host stars to be observed by COROT were characterized using the 2.5m Isaac Newton Telescope at the Observatorio Roque de las Muchachos in La Palma, Canary Islands. The mass of the first COROT planet was measured using the SOPHIE (Spectrograph for Observation of Astroseismologic Phenomenon and Extrasolar Planets) spectrograph at the Observatoire de Haute Provence (OHP) in France.

The 2m telescope at Tautenburg Observatory in Germany was also used to measure the mass of another COROT candidate which turned out to be a binary star. In the future, spectroscopic observations will also be made using ESO telescopes in Chile, including the HARPS instrument at La Silla Observatory and the Very Large Telescope (VLT) at Paranal Observatory, both in Chile.

Photometric follow-up observations are also needed. The first candidates were followed up using the 1m telescope at Wise Observatory in Israel and the 80cm telescope of the Instituto de Astrofisica de Canarias at the Observatorio del Teidy in Tenerife , Canary Islands. Also foreseen for this purpose are the 1m ESA telescope, also in Tenerife, and the Swiss 1m Euler telescope at La Silla Observatory in Chile.