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arXiv 1202.2801astro-ph.EP
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比较HARPS和开普勒巡天:多行星系统的排列

Comparing HARPS and Kepler surveys: The alignment of multiple-planet systems

P. Figueira, M. Marmier, G. Boué, C. Lovis, N. C. Santos, M. Montalto, S. Udry, F. Pepe, M. Mayor

摘要:

目标。我们研究的一个子集的行星人口的特点是HARPS和开普勒调查。我们比较了m.sin i >5-10 M_Earth和R>2 R_Earth系统中行星的统计性质。如果我们假设潜在的种群具有相同的特征,那么相对于视线的轨道倾角的不同检测灵敏度允许我们探测行星的相互倾角。方法.我们考虑了HARPS数据所指示的具有一颗、两颗和三颗行星的系统的频率。我们使用开普勒的行星周期和主机的质量和半径分布(从检测偏差校正)模型行星系在一个简单的物理合理的方式。然后,我们根据不同的规定(完全对齐,瑞利分布和各向同性)改变系统中行星之间的相互倾斜,并将一个,两个或三个行星的过境频率与开普勒测量的频率进行比较。结果结果表明,这两个数据集是兼容的,一个显着的结果,特别是因为没有可调旋钮以外的假设倾斜分布。对于7-10 M_Earth的m.sin i截止值,这是预期对应于2 R_Earth的半径截止值的那些,我们得出结论,用具有1度或更小模式的瑞利分布来描述结果更好。我们表明,最适合的情况下,只有成为一个瑞利分布模式的5度,如果我们假设一个相当极端的质量半径关系的行星人口。结论.这些结果有重要的后果,我们的理解的作用,几个建议的形成和演变机制。他们证实了行星很可能是在一个圆盘中形成的,并表明大多数行星系在没有强烈角动量交换的情况下安静地演化。

英文摘要:

Aims. We study a subset of the planetary population characterized both by HARPS and Kepler surveys. We compare the statistical properties of planets in systems with m.sin i >5-10 M_Earth and R>2 R_Earth. If we assume that the underlying population has the same characteristics, the different detection sensitivity to the orbital inclination relative to the line of sight allows us to probe the planets' mutual inclination. Methods. We considered the frequency of systems with one, two and three planets as dictated by HARPS data. We used Kepler's planetary period and host mass and radii distributions (corrected from detection bias) to model planetary systems in a simple yet physically plausible way. We then varied the mutual inclination between planets in a system according to different prescriptions (completely aligned, Rayleigh distributions and isotropic) and compared the transit frequencies with one, two or three planets with those measured by Kepler. Results. The results show that the two datasets are compatible, a remarkable result especially because there are no tunable knobs other than the assumed inclination distribution. For m.sin i cutoffs of 7-10 M_Earth, which are those expected to correspond to the radius cutoff of 2 R_Earth, we conclude that the results are better described by a Rayleigh distribution with mode of 1 deg or smaller. We show that the best-fit scenario only becomes a Rayleigh distribution with mode of 5 deg if we assume a rather extreme mass-radius relationship for the planetary population. Conclusions. These results have important consequences for our understanding of the role of several proposed formation and evolution mechanisms. They confirm that planets are likely to have been formed in a disk and show that most planetary systems evolve quietly without strong angular momentum exchanges (abridged).

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