Search for new objects with microlensing follow-up observations

点击翻译按钮获取中文摘要

Searches for extra-solar planets with gravitational microlensing need detailed analyses of the light curves of the light curves of the microlensing events. To do so, intensive follow-up observations are necessary as well as the event survey.This project is aimed to do timely follow-up observations with world-wide telescope networks. The observations have been done with Mt. John 61-cm telescope, Ishigaki 105cm telescope, and collaborations with world-wide telescope networks. From the analyses of the obtained light curves, a giant planet was discovered in OGLE 2005-BLG-071. It was the second planet discovered with microlensing. Then, a 5.5 Earth mass planet was discovered in OGLE 2005-BLG-390. It was the first icy planet discovered outside of our solar system. Furthermore, a planetary system very similar to our Jupiter and Saturn was discovered in OGLE 2006-BLG-109. It was the first planetary system discovered with microlensing and showed effectiveness of this method to find such planetary systems. Discoveries of planets continued. In 2007, four candidates (MOA 2007-BLG-192, 197, 308, and 379) have been discovered and the analyses are in progress.These results showed new scope of extrasolar planets which is hard to study with conventional radial-velocity method. The results of microlensing may show the planets like our solar system may be very common in the universe. The discovery of low-mass planet in OGLE 2005-BLG-390 showed effectiveness of this method in finding low-mass planets and showed future possibility of finding Earth-mass planet.