In the animation, we see the behaviour of the light-curve when a large starspot is present on the stellar surface (shown in blue). Another, smaller starspot appears at a different latitude, rotating with a different velocity. The light-curve in the animation can be compared to the one observed in the next figure it can be seen that it is a reasonable interpretation.

Credits: CNES (Animation by Patrice Amoyel)

Delta Scuti is a class of variable stars in which the variations found (for example also in the Sun) are exaggerated, and thus are easier to study. Scientists expect to increase their understanding of the mechnaisms causing stellar variability by observing several Delta Scuti stars with COROT.

The different peaks provide information about the internal constituency of the star. The level of detection from the ground is represented by the red horizontal line.

Credits: COROT exo-team

The observation was carried out for 140 days. The light-curve contains 78 passages of the planet in front of the star. This is a record, compared to previous (ground-based) observations where transits sometimes take place in the daytime and are impossible to observe.

The photometric precision obtained in this light-curve is also without precedence, and remains constant during the whole sequence. It reaches 160 parts per million in an integration time of 2.5 minutes – a value impossible to obtain with any ground-based instrument. The light-curve also contains much information about the star itself. It shows periodic modulations, probably the result of different rotational velocities at different latitudes of the star.

This is another nice example of COROT’s superior performance and demonstrates the impact that this mission will have on our understanding of stellar activity and its connection to extrasolar planets.

Credits: COROT exo-team