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arXiv 1405.0960astro-ph.EP
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自旋轨道角分布和(错)排列热电子的起源

Spin-Orbit angle distribution and the origin of (mis)aligned hot Jupiters

Aurélien Crida, Konstantin Batygin

摘要:

对61颗凌日热彗星,测量了轨道平面与恒星赤道夹角的投影(称为自旋轨道角)。其中大约一半的行星被发现有明显的错位,并观察到逆行行星。这挑战了热凝结物形成的情景。为了更好地约束编队模型,我们将实际自旋轨道角$Ψ$的分布与投影角$β$的分布联系起来。然后,与观察结果进行比较是相关的。我们分析的几何问题,解析链接的投影角$β$到真正的自旋轨道角$Ψ$。在各种模型中预期的$Ψ$的分布取自文献,或者在盘扭矩机构的情况下,用简化模型和蒙特卡罗模拟推导。给出了在已知$Ψ$概率密度函数的情况下计算$β$概率密度函数的简便公式。这里测试的所有模型看起来都与观察到的40度以上的分布相兼容,到目前为止,只有18个观测值对该分布的约束很差。但是,只有磁盘扭矩机制可以解释对齐的热蒸发器的过量,只要扭矩并不总是有效的。如果令人兴奋的双星有10000 AU的半长轴,就会出现这种情况。根据与现有观测资料的比较,散射模型和具有潮汐摩擦模型的Kozai循环不能单独负责所有热对流层的产生。相反,目前观测到的自旋轨道角分布与大多数热彗星是通过原行星盘内部的平滑迁移而被运送的是一致的,而原行星盘本身可能被伴星扭转。

英文摘要:

For 61 transiting hot Jupiters, the projection of the angle between the orbital plane and the stellar equator (called the spin-orbit angle) has been measured. For about half of them, a significant misalignment is detected, and retrograde planets have been observed. This challenges scenarios of the formation of hot Jupiters. In order to better constrain formation models, we relate the distribution of the real spin-orbit angle $Ψ$ to the projected one $β$. Then, a comparison with the observations is relevant. We analyse the geometry of the problem to link analytically the projected angle $β$ to the real spin-orbit angle $Ψ$. The distribution of $Ψ$ expected in various models is taken from the literature, or derived with a simplified model and Monte-Carlo simulations in the case of the disk-torquing mechanism. An easy formula to compute the probability density function (PDF) of $β$ knowing the PDF of $Ψ$ is provided. All models tested here look compatible with the observed distribution beyond 40 degrees, which is so far poorly constrained by only 18 observations. But only the disk-torquing mechanism can account for the excess of aligned hot Jupiters, provided that the torquing is not always efficient. This is the case if the exciting binaries have semi-major axes as large as 10000 AU. Based on comparison with the set of observations available today, scattering models and the Kozai cycle with tidal friction models can not be solely responsible for the production of all hot Jupiters. Conversely, the presently observed distribution of the spin-orbit angles is compatible with most hot Jupiters having been transported by smooth migration inside a proto-planetary disk, itself possibly torqued by a companion.

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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