The MEarth Project: A Transit Search for Rocky Planets in the Habitable Zones of Low-mass Stars

MEarth 项目：在低质量恒星的宜居带中寻找岩石行星

• 批准号: 0807690
• 负责人: David Charbonneau
• 金额: $ 55.72万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0807690&HistoricalAwards=false
• 关键词: MEarth; Project; Transit; Search; Rocky

Nearby, low-mass M-dwarf stars are particularly attractive targets for transit surveys to detect small, rocky planets orbiting within their stellar habitable zones. Unlike their Sun-like counterparts, terrestrial planets transiting late M-dwarfs present a photometric signal that is of sufficient depth as to permit detection with ground-based observatories. Moreover, the low stellar luminosities imply that the habitable zones are located at small orbital distances from the central star, which in turn suggests detection of planets in their habitable zones should be facilitated by the higher geometric probability of a transit, and by the reduced orbital period and hence time span required to detect such an event.Here, Dr. Charbonneau will lead a 3-year survey of the 2000 nearest late M-dwarfs with a cadence and sensitivity sufficient to detect habitable-zone planets with radii as small as twice that of the Earth. The survey will be conducted at the MEarth Observatory at Mt Hopkins in southern Arizona, which consists of 8 identical 40cm CCD-based telescopes located in a single roll-off enclosure. By sequentially surveying only nearby, well-characterized targets, MEarth overcomes the severe problems of false-positive contamination that have plagued extant wide-field surveys. It is expected that the survey will either detect large, habitable-zone terrestrial exoplanets, or yield an upper limit (with 99% confidence) of 17% on their rate of occurrence. In the event of a detection, these planets will (1) provide the first constraints on models of the physical structure and composition of terrestrial exoplanets, (2) inform models of the planetary formation around low-mass stars, and (3) provide keystone targets for subsequent studies of their atmospheres, which in turn will permit an understanding of the atmospheric chemistry and dynamics for terrestrial exoplanets.Through this project, postdoctoral fellows, graduate students and undergraduates will be trained through access to a cutting-edge research opportunity in the rapidly-evolving field of exoplanet science. The results will be disseminated broadly by Dr. Charbonneau and the project participants through a series of publications in refereed journals, articles in popular science magazines, talks at astronomical and interdisciplinary research conferences, and a project webpage geared for the general public.

附近的低质量 M 矮星是凌日巡天特别有吸引力的目标，以探测在其恒星宜居带内运行的小型岩石行星。与类似太阳的行星不同，凌日晚期 M 矮星的类地行星呈现出足够深度的光度信号，足以允许地面天文台进行探测。此外，低恒星光度意味着宜居带位于距中心恒星较小的轨道距离处，这反过来表明，凌星的几何概率较高，轨道周期缩短，因此检测此类事件所需的时间跨度也相应缩短，从而有助于对宜居带中的行星进行探测。在这里，Charbonneau 博士将领导一项为期 3 年的调查，对 2000 个最近的晚期 M 矮星进行了一项为期 3 年的调查， 节奏和灵敏度足以探测半径只有地球两倍的宜居带行星。这项调查将在亚利桑那州南部霍普金斯山的 MEarth 天文台进行，该天文台由 8 个相同的 40 厘米 CCD 望远镜组成，位于一个滚降外壳中。通过仅对附近的、特征明确的目标进行顺序调查，MEarth 克服了困扰现有广域调查的假阳性污染的严重问题。预计该调查将探测到大型宜居带类地系外行星，或者得出其出现率的上限（99% 置信度）为 17%。 一旦被发现，这些行星将（1）为类地系外行星的物理结构和组成模型提供第一个约束，（2）为低质量恒星周围的行星形成模型提供信息，（3）为后续研究其大气层提供关键目标，这反过来又将使人们了解类地系外行星的大气化学和动力学。通过这个项目，博士后研究员， 研究生和本科生将通过获得快速发展的系外行星科学领域的尖端研究机会来接受培训。夏博诺博士和项目参与者将通过在参考期刊上发表的一系列出版物、科普杂志上的文章、在天文学和跨学科研究会议上的演讲以及面向公众的项目网页来广泛传播研究结果。