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arXiv 0907.0020astro-ph.EP
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哪些径向速度系外行星有未被发现的外部伴侣?

Which Radial Velocity Exoplanets Have Undetected Outer Companions?

Timothy J. Rodigas, Philip M. Hinz

摘要:

在单行星系统中观测到的太阳系外行星的径向速度(RV)偏心率分布表明,相当一部分行星是偏心的($e > 0.1$)。在这里,我们调查的RV行星的偏心率产生的未被发现的外部同伴的影响。我们对模拟RV数据进行了蒙特卡罗模拟,以了解这种效应并预测其对观察到的分布的影响。我们首先量化未检测到的外部同伴的统计效应,并表明,这本身不能解释所观察到的分布。然后,我们修改的模拟,包括两个人口,一个零偏心率的行星在双行星系统和其他单行星从偏心分布。我们的模拟结果表明,一个很好的拟合所观察到的分布与45%的零偏心双行星和55%的单偏心行星。与观测到的分布相匹配,使我们能够确定一个已知的RV行星的轨道偏心率被一个未被发现的宽分离伴星所偏置的概率。我们的模拟表明,中等偏心的行星,与$0.1 < e < 0.3$和$0.1 < e < 0.2$,有一个$\sim 13%$和$\sim 19%$的概率,分别有一个未被发现的外伴星。我们鼓励高对比度直接成像和RV后续调查已知RV行星与中等偏心率,以测试我们的预测,并寻找以前未被发现的外部同伴。

英文摘要:

(Abridged) The observed radial velocity (RV) eccentricity distribution for extrasolar planets in single-planet systems shows that a significant fraction of planets are eccentric ($e > 0.1$). Here we investigate the effects on an RV planet's eccentricity produced by undetected outer companions. We have carried out Monte Carlo simulations of mock RV data to understand this effect and predict its impact on the observed distribution. We first quantify the statistical effect of undetected outer companions and show that this alone cannot explain the observed distribution. We then modify the simulations to consist of two populations, one of zero-eccentricity planets in double-planet systems and the other of single planets drawn from an eccentric distribution. Our simulations show that a good fit to the observed distribution is obtained with 45% zero-eccentricity double-planets and 55% single eccentric planets. Matching the observed distribution allows us to determine the probability that a known RV planet's orbital eccentricity has been biased by an undetected wide-separation companion. Our simulations show that moderately-eccentric planets, with $0.1 < e < 0.3$ and $0.1 < e < 0.2$, have a $\sim 13%$ and $\sim 19%$ probability, respectively, of having an undetected outer companion. We encourage both high-contrast direct imaging and RV follow-up surveys of known RV planets with moderate eccentricities to test our predictions and look for previously undetected outer companions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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