Extrasolar planet systems: Status report

The study of exoplanets is definitely one of the most exciting and newly developing fields in astronomy and planetary science in the last two decades. The new field attracts some many bright young scientist. The findings are enchanting the public as well. The recent progress in the field has been phenomenal. Only about 20 years have passed since the first discoveries of giant exoplanets with the Doppler method. Today we have discovered more than 500 planets in orbit around mostly nearby stars. The first terrestrial mass objects are also discovered in this retrival. We characterize exoplanets in terms of their mass, radius, and mean density and thus have been able to construct the first crude models of their internal structure. We have also measured the albedo, effective temperature, and some atmospheric features of several short period giant planets (Seager, 2008). In the middle of 1990?s these discoveries could not have even been imagined by researchers working in this, then unnoticed field. Although significant progress has been made, astronomers has to travel a long way before they can truly start comparative planetology, and fully understand the process of planet formation, and also know, ultimately, how our own solar system formed and how life originated on one of its terrestrial planets.The detection of exoplanets is a new field requiring a diverse range of astronomical measurements at their extreme limits: radial velocity precisions are of 0.1 ? 1 m/s, astrometric measurements, of a few micro-arcseconds, angular resolutions, of a few milli-arcseconds, and the measurement of contrast ratios of ~10-10. The needs of the exoplanet search community are also the drivers of new Technologies. Most of these ?extreme? measurements often require expensive space missions.Another, often applied method, the planetary eclipses make use of quite simple and in a way archaic technique much used in binary stars observations, in determining the eclipse duration and system periods. However, it need to be pushed to its limits mainly in terms of since the eclipsing body now is a planet, much smaller than any types of star, with no light of its own. Such observations also require the coordination of international campaigns to determine longer period (~1/2 day) systems. One such campaign (transit event of HD80606b) in which COMU group and author of present thesis participated included several countries from US to Turkey. Although, the coordination efforts and campaign are still not completed, a short account of the international cooperation and is early results will also be summarised.