The transit light curve

The transit light curve
The transit light curve gives an astronomer a wealth of information about the transiting planet as well as the star. It is only for transiting exoplanets that astronomers have been able to get direct estimates of the exoplanet mass and radius. With these parameters at hand astronomers are able to set the most fundamental constraints on models which reveal the physical nature of the exoplanet, such as its average density and surface gravity.

As mentioned above the transit events do not just give information about the exoplanet, but quite often also information about the star. With telescopes capable of high precision photometry, transit curve anomalies can say something about the activity of the star. An example of this is when an exoplanet crosses star spots. This can be seen in the light curve as a small increase in flux due to the light of a cooler part of the star being blocked out.

With a very high precision light curve with a high Signal to Noise (S/N), the light curve can also be used to infer the presence of other planets in the system. Perturbations in the timing of exoplanet transits may be used to infer the presence of satellites or additional planetary companions.

Source, credit and further reading:
http://www.paulanthonywilson.com/exoplanets/exoplanet-transits-transmission-spectroscopy/the-transit-light-curve/

References:
http://adsabs.harvard.edu/abs/2007prpl.conf..701C
http://adsabs.harvard.edu/abs/2001ApJ...553.1006B
http://adsabs.harvard.edu/abs/2002ApJ...564.1019M