Search for new objects with microlensing follow-up observations

寻找具有引力微透镜的太阳系外行星需要对微透镜事件的光曲线进行详细分析。要做到这一点，除了事件调查外，密集的后续观测也是必要的。这个项目的目的是利用世界范围的望远镜网络进行及时的后续观测。这些观测已经在Mt.约翰61厘米望远镜、石垣105厘米望远镜，以及与全球望远镜网络的合作。通过对获得的光曲线的分析，在OGLE 2005-BLG-071中发现了一颗巨行星。这是第二颗用微透镜发现的行星。然后，在Ogl2005-BLG-390中发现了一颗质量为5.5地球的行星。这是在太阳系外发现的第一颗冰行星。此外，在Ogl2006-BLG-109中发现了一个与我们的木星和土星非常相似的行星系统。这是第一个用微透镜发现的行星系统，并显示了这种方法在寻找这样的行星系统方面的有效性。行星的发现还在继续。2007年发现了4个候选行星(MOA2007-BLG-192、197、308和379)，并正在进行分析。这些结果显示了用传统的径向速度方法难以研究的太阳系外行星的新范围。微透镜的结果可能表明，像我们太阳系这样的行星在宇宙中可能非常常见。在OGLE 2005-BLG-390上发现的低质量行星表明了该方法在寻找低质量行星方面的有效性，并展示了未来发现地球质量行星的可能性。

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.