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

利用引力微透镜寻找太阳系外行星和暗星

基本信息

批准号：
19340058
负责人：
MURAKI Yasushi
金额：
$ 11.9万
依托单位：
Konan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2007
资助国家：
日本
起止时间：
2007 至 2010
项目状态：
已结题

项目摘要

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

日本-新西兰天文学合作被称为MOA（天体物理学微透镜观测），成立于1995年，目的是寻找MACHO（大质量致密晕天体）形式的暗物质成分，并使用引力微透镜技术寻找太阳系外行星。这种技术利用恒星和其他大质量物体的引力场，有效地在太空中形成广义相对论所预测的大透镜。微透镜技术的可行性是由Bohdan Paczynski在1986年指出的。他建议在麦哲伦星云和银河系隆起中监测尽可能多的恒星，以寻找银河系晕或银河系盘中的引力透镜。MOA合作于1995年开始使用新西兰约翰山天文台的0.6米望远镜进行观测。2005年，日本在约翰山安装了一台1.8米的望远镜。从那时起，每年都有超过500个微透镜事件被发现朝向银河系隆起。还有， ...更多信息天文台发现的事件已通过万维网公开发布，以便其他天文台能够监测选定的事件，特别是那些具有高放大率的事件。这导致了在银河系盘和银河系隆起中发现了16颗围绕恒星运行的太阳系外行星。这些行星是在它们的主星的雪线之外被发现的。这是微透镜技术最灵敏的区域，也是根据核心吸积理论形成冰巨星和气体巨星的区域。这些行星的数据补充了通过径向速度和凌日技术获得的更近距离行星的数据。除了上述发现外，MOA还发现了一类新的太阳系外行星。这些行星不受恒星的约束。它们的质量与木星相当，数量与银河系中的恒星相当。最后，MOA的甲南大学小组完成了对1999年至2005年期间使用约翰山0.6米望远镜对大麦哲伦星云观测结果的分析。大约发现了9,000颗Miras和13,000颗Cepheid变星。这些结果将在其他地方介绍。少