Search for Extra-solar Planet and Dark Stars by Gravitational Microlensing

日本-新西兰天文学合作被称为MOA（天体物理学中的微透镜观测），成立于1995年，目的是以MACHOs（大质量致密光晕天体）的形式寻找暗物质的组成部分，并利用引力微透镜技术寻找太阳系外的行星。这项技术利用恒星和其他大质量物体的引力场，在太空中有效地形成广义相对论所预测的大透镜。1986年，Bohdan Paczynski指出了微透镜技术的可行性。他建议在麦哲伦星云和星系凸起中尽可能多地监测恒星，以在星系晕或星系盘中找到引力透镜。MOA合作项目于1995年开始使用位于新西兰约翰山天文台的0.6米望远镜进行观测。2005年，日本在约翰山上安装了一个1.8米的望远镜。从那时起，每年都有500多个微透镜事件被发现指向银河系凸起。此外，在麦哲伦星云的方向上发现了更多的事件。MOA发现的事件通过万维网公开提供，使其他天文台能够监测选定的事件，特别是那些具有高放大倍数的事件。结果发现了16颗太阳系外行星，它们围绕着星系盘和星系凸起的恒星运行。这些行星是在它们的主恒星的雪线之外被发现的。这是微透镜技术灵敏度最高的区域，根据核心吸积理论，这也是冰巨星和气体巨星形成的区域。这些行星的数据补充了通过径向速度和凌日技术在更近的行星上获得的数据。除了上述发现外，MOA还发现了一类新的系外行星。这些行星并不局限于恒星。它们的质量与木星的质量相似，它们的数量几乎与银河系中的恒星一样多。最后，科南大学的MOA小组用约翰山的0.6米望远镜完成了1999年至2005年对大麦哲伦星云的观测分析。大约发现了9000颗Miras和13000颗造父变星。这些结果将在其他地方公布。少

The Japan-NZ astronomy collaboration known as MOA (Microlensing Observations in Astrophysics) was formed in 1995 with the aim of searching for a component of dark matter in the form of MACHOs (Massive Compact Halo Objects) and also for extra-solar planets using the gravitational microlensing technique. This technique uses the gravitational fields of stars and other massive objects to effectively form large lenses in space as predicted by general relativity. The feasibility of the microlensing technique was pointed out by Bohdan Paczynski in 1986. He proposed monitoring as many stars as possible in the Magellanic Clouds and the galactic bulge to find gravitational lenses in the galactic halo or the galactic disc.The MOA collaboration commenced observations in 1995 using a 0.6m telescope at the Mt John observatory in NZ. In 2005 a 1.8m telescope was installed at Mt John by Japan. Since that time more than 500 microlensing events have been found each year towards the galactic bulge. Also, … More events have been found towards the Magellanic Clouds.The events found by MOA were made publicly available via the world wide web to enable other observatories to monitor selected events, in particular those with high magnifications. This resulted in the discovery of 16 extra-solar planets orbiting stars in the galactic disc and the galactic bulge. These planets were found just beyond the snowlines of their host stars. This is the region of maximum sensitivity of the microlensing technique, and it also the region where ice-giant and gas-giant planets form according to the core accretion theory. The data on these planets complements data being obtained on closer-in planets by the radial velocity and transit techniques.In addition to the above discoveries, a new class of extra-solar planets was discovered by MOA. These planets are not bound to stars. They have masses similar to that of Jupiter, and they are approximately as abundant as stars in the galaxy.Finally, the Konan University group of MOA completed the analysis of observations made between 1999 and 2005 towards the Large Magellanic Cloud with the 0.6m telescope at Mt John. Approximately 9,000 Miras and 13,000 Cepheid variable stars were found. Those results will be presented in elsewhere. Less