HOW TO DETERMINE AN EXOMOON'S SENSE OF ORBITAL MOTION
HOW TO DETERMINE AN EXOMOON'S SENSE OF ORBITAL MOTION
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如何确定外卫星的轨道运动
DOI：
10.1088/2041-8205/796/1/l1
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
S. Albrecht
中科院分区：
文献类型：
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作者：
R. Heller;S. Albrecht
我们提出了两种方法来确定外卫星的轨道运动感(SOM)，一种是相对于行星的星际轨道，另一种是相对于行星的自转。我们的模拟表明，使用欧洲极大望远镜(E-ELT)可以进行所需的测量。第一种方法依赖于恒星凌日期间相互的行星-月球事件。月食由于有限的光速，月球经过地球的后面(前面)时，行星相对于月球的平均轨道周期会晚(早)。这种“凌日计时二分法”(TTD)决定了外星相对于恒星周行运动的SOM。对于太阳系中最大的10颗卫星，TTD的范围在2到12 S之间。E-ELT将能够对附近类太阳恒星周围的地球大小的卫星进行这样的测量。第二种方法测量了这颗旋转的巨行星在其月球凌日时的红外光谱失真。行星光谱中的Rossiter-McLaughlin效应(RME)揭示了行星赤道和月球绕行星轨道平面之间的角度，从而揭示了月球相对于行星自转的SOM。一颗相当大的卫星经过一颗直接成像的行星，如βPic b，产生的RME振幅约为100 m S−1，大约是凌日系外行星HD209458b的恒星RME振幅的两倍。这两种新方法都可以用来探测系外卫星的起源，也就是说，无论它们是规则的还是不规则的。
We present two methods to determine an exomoon's sense of orbital motion (SOM), one with respect to the planet's circumstellar orbit and one with respect to the planetary rotation. Our simulations show that the required measurements will be possible with the European Extremely Large Telescope (E-ELT). The first method relies on mutual planet–moon events during stellar transits. Eclipses with the moon passing behind (in front of) the planet will be late (early) with regard to the moon's mean orbital period due to the finite speed of light. This “transit timing dichotomy” (TTD) determines an exomoon's SOM with respect to the circumstellar motion. For the 10 largest moons in the solar system, TTDs range between 2 and 12 s. The E-ELT will enable such measurements for Earth-sized moons around nearby Sun-like stars. The second method measures distortions in the IR spectrum of the rotating giant planet when it is transited by its moon. This Rossiter–McLaughlin effect (RME) in the planetary spectrum reveals the angle between the planetary equator and the moon's circumplanetary orbital plane, and therefore unveils the moon's SOM with respect to the planet's rotation. A reasonably large moon transiting a directly imaged planet like β Pic b causes an RME amplitude of almost 100 m s−1, about twice the stellar RME amplitude of the transiting exoplanet HD209458 b. Both new methods can be used to probe the origin of exomoons, that is, whether they are regular or irregular in nature.
太阳系外行星伴星系统相互凌日对光曲线的影响
DOI：
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发表时间：
2009
期刊：
Publ. Astron. Soc. Jap
影响因子：
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作者：
M. Sato;H. Asada
通讯作者：
H. Asada