Astrometric detection of giant planets around nearby M dwarfs: the Gaia potential
Astrometric detection of giant planets around nearby M dwarfs: the Gaia potential
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对附近 M 型矮星周围巨行星的天体测量探测：盖亚势
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发表时间：
2013
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通讯作者：
Giovanna Tinetti
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作者：
A. Sozzetti;P. Giacobbe;P. Giacobbe;M. Lattanzi;G. Micela;R. Morbidelli;Giovanna Tinetti
距离太阳几十秒差距内的冷M矮星正在成为系外行星天体物理学领域专门观测计划的焦点。盖亚，在其全天空调查>10 9个对象，将提供精确的天体测量的星等有限（V = 20）的样本M矮星。我们研究了附近M矮星的盖亚天体测量数据与其他用于行星探测和表征的地基和星载计划之间协同作用的某些方面。我们进行了数值模拟，以衡量盖亚潜在的精确天体测量的系外行星轨道上的一个样本已知的dM恒星在1030秒差距从太阳。我们表示盖亚探测阈值作为系统参数的函数，并鉴于最新的使命配置文件，包括最新的天体测量误差模型。我们的主要发现如下：（1）对于轨道周期在0.2P6.0 yr范围内，天体测量信噪比为σ/ σAL 10的大质量行星，精确测定其轨道和质量是可能的。根据目前对M矮星周围的行星分数fp的估计，盖亚可能会在样本周围发现102颗巨行星。盖亚在100 pc范围内对104 × 105 M的矮星库进行全面筛选，可以进行2600次探测和多达2500次精确的轨道测定。这样就可以以2%的精确度确定fp值，这比迄今为止最精确的数值提高了一个数量级以上;（2）在同期范围内，将以足够的精度确定对应于准边缘上配置的倾斜角（百分之几），以便有可能识别可能在误差范围内过境的中间分离行星。盖娅可以警告我们存在10个这样的系统。假设与过境配置兼容的解决方案在10%的准确度内，可以确定250多个候选者，尽管其中很大一部分（85%）可能是误报;（3）对于采样良好的轨道，
Cool M dwarfs within a few tens of parsecs from the Sun are becoming the focus of dedicated observational programs in the realm of exoplanet astrophysics. Gaia, in its all-sky survey of >10 9 objects, will deliver precision astrometry for a magnitude-limited (V = 20) sample of M dwarfs. We investigate some aspects of the synergy between the Gaia astrometric data on nearby M dwarfs and other ground-based and space-borne programs for planet detection and characterization. We carry out numerical simulations to gauge the Gaia potential for precision astrometry of exoplanets orbiting a sample of known dM stars within ∼30 pc from the Sun. We express Gaia detection thresholds as a function of system parameters and in view of the latest mission profile, including the most up-to-date astrometric error model. Our major findings are as follows: (1) it will be possible to accurately determine orbits and masses for Jupiter-mass planets with orbital periods in the range 0.2 P 6.0 yr and with an astrometric signal-to-noise ratio ς/ σAL 10. Given present-day estimates of the planet fraction fp around M dwarfs, ≈10 2 giant planets could be found by Gaia around the sample. Comprehensive screening by Gaia of the reservoir of ∼4 × 10 5 M dwarfs within 100 pc could result in ∼2600 detections and as many as ∼500 accurate orbit determinations. The value of fp could then be determined with an accuracy of 2 per cent, an improvement by over an order of magnitude with respect to the most precise values available to-date; (2) in the same period range, inclination angles corresponding to quasi-edge-on configurations will be determined with enough precision (a few per cent) so that it will be possible to identify intermediateseparation planets which are potentially transiting within the errors. Gaia could alert us of the existence of 10 such systems. More than 250 candidates could be identified assuming solutions compatible with transit configurations within 10 per cent accuracy, although a large fraction of these (∼85 per cent) could be false positives; (3) for well-sampled orbits, the �