The Keck Planet Search: Detectability and the minimum mass and orbital period distribution of extrasolar planets
The Keck Planet Search: Detectability and the minimum mass and orbital period distribution of extrasolar planets
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DOI：
10.1086/588487
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发表时间：
2008-05-01
影响因子：
3.5
通讯作者：
Fischer, Debra A.
中科院分区：
文献类型：
--
作者：
Cumming, Andrew;Butler, R. Paul;Fischer, Debra A.
我们分析了凯克行星搜索 8 年的精确径向速度测量结果，描述了探测阈值、选择效果和调查的完整性。我们首先通过评估与数据拟合的开普勒轨道相关的误报概率，对行星进行系统搜索。这使我们能够根据观测的数量和时间基线来了解每颗恒星的检测阈值，以及来自测量误差、固有恒星抖动或其他低质量行星的潜在“噪声”。我们证明所有行星的轨道周期 P < 2000 天，速度振幅 K > 20 ms(-1)，偏心率 e。 0：6已经公布，我们总结了较低振幅和较长轨道周期的候选者。对于其余恒星，我们计算伴星速度幅度的上限。对于小于观测持续时间的轨道周期，这些周期通常为 10 ms(-1) 并且会增加。 α P(2) 的时间较长。然后，我们使用未探测到的结果来导出低振幅和长轨道周期的完整性校正，并讨论由此产生的最小质量和轨道周期的分布。我们将拥有行星的恒星比例作为最小质量和轨道周期的函数，并推断出长周期轨道和低行星质量。行星质量 > 0.3 M(J) 且周期 < 2000 天的幂律拟合给出质量周期分布 dN = CM(alpha)P(beta)d In Md In P，其中 alpha = -0.31 +/- 0.2，beta = 0.26 +/- 0.1，以及标准化常数 C，使得 10.5% 的太阳型恒星拥有质量在 0.3-10 范围内的行星M(J) 和轨道周期 2-2000天。轨道周期分布显示，对于大于或类似于 300 天的轨道周期，行星比例增加了大约 5 倍。外推得出 17%-20% 的恒星在 20 个天文单位内拥有气态巨行星。最后，考虑到可探测性的差异，我们限制了绕 M 矮星运行的行星与 FGK 矮星运行的行星的出现率。
We analyze 8 years of precise radial velocity measurements from the Keck Planet Search, characterizing the detection threshold, selection effects, and completeness of the survey. We first carry out a systematic search for planets, by assessing the false-alarm probability associated with Keplerian orbit fits to the data. This allows us to understand the detection threshold for each star in terms of the number and time baseline of the observations, and the underlying "noise" from measurement errors, intrinsic stellar jitter, or additional low-mass planets. We show that all planets with orbital periods P < 2000 days, velocity amplitudes K > 20 ms(-1), and eccentricities e. 0: 6 have been announced, and we summarize the candidates at lower amplitudes and longer orbital periods. For the remaining stars, we calculate upper limits on the velocity amplitude of a companion. For orbital periods less than the duration of the observations, these are typically 10 ms(-1) and increase. alpha P(2) for longer periods. We then use the nondetections to derive completeness corrections at low amplitudes and long orbital periods and discuss the resulting distribution of minimum mass and orbital period. We give the fraction of stars with a planet as a function of minimum mass and orbital period and extrapolate to long-period orbits and low planet masses. A power-law fit for planet masses > 0.3 M(J) and periods < 2000 days gives a mass-period distribution dN = CM(alpha)P(beta)d In Md In P with alpha = -0.31 +/- 0.2, beta = 0.26 +/- 0.1, and the normalization constant C such that 10.5% of solar type stars have a planet with mass in the range 0.3-10 M(J) and orbital period 2-2000 days. The orbital period distribution shows an increase in the planet fraction by a factor of approximate to 5 for orbital periods greater than or similar to 300 days. Extrapolation gives 17%-20% of stars having gas giant planets within 20 AU. Finally, we constrain the occurrence rate of planets orbiting M dwarfs compared to FGK dwarfs, taking into account differences in detectability.