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arXiv 1005.4050astro-ph.EP
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径向速度行星已消除锯齿。一个新的,短时期的超级地球55数控e

Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e

Rebekah I. Dawson, Daniel C. Fabrycky

摘要:

恒星反射运动的径向速度测量揭示了许多太阳系外行星,但观测中的差距产生了别名,虚假频率经常与行星的轨道频率混淆。在Gl 581 d的情况下,别名和真实频率之间的区别是冰冻的死亡行星和可能适合生命的行星之间的区别(Udry等人2007; Mayor等人2009)。为了改善行星系的表征,我们描述了如何别名的起源,并提出了一种新的方法来区分轨道频率和它们的别名。我们的方法利用频谱窗口函数中的特征来比较预测混叠的幅度和相位与数据中存在的峰值。我们应用它来确认行星GJ 876 d和HD 75898 b之前的别名区别。我们发现Gl 581 d和HD 73526 b/c的真实周期仍然不明确。我们修正了HD 156668 b和55 Cnc e的周期,这些周期受到日常别名的影响。对于HD 156668 b,正确的周期是1.2699天,最小质量是(3.1 +/- 0.4)地球质量。对于55 Cnc e,正确的周期是0.7365天-任何已知行星中最短的-最小质量是(8.3 +/- 0.3)地球质量。这一修订产生了一个显着改善的5行星开普勒适合55 Cnc,和自洽的动力学拟合描述的数据一样好。随着径向速度技术不断推进到更小的行星,通常在多行星系统中发现,区分真实的周期和别名将变得越来越重要。

英文摘要:

Radial velocity measurements of stellar reflex motion have revealed many extrasolar planets, but gaps in the observations produce aliases, spurious frequencies that are frequently confused with the planets' orbital frequencies. In the case of Gl 581 d, the distinction between an alias and the true frequency was the distinction between a frozen, dead planet and a planet possibly hospitable to life (Udry et al. 2007; Mayor et al. 2009). To improve the characterization of planetary systems, we describe how aliases originate and present a new approach for distinguishing between orbital frequencies and their aliases. Our approach harnesses features in the spectral window function to compare the amplitude and phase of predicted aliases with peaks present in the data. We apply it to confirm prior alias distinctions for the planets GJ 876 d and HD 75898 b. We find that the true periods of Gl 581 d and HD 73526 b/c remain ambiguous. We revise the periods of HD 156668 b and 55 Cnc e, which were afflicted by daily aliases. For HD 156668 b, the correct period is 1.2699 days and minimum mass is (3.1 +/- 0.4) Earth masses. For 55 Cnc e, the correct period is 0.7365 days -- the shortest of any known planet -- and minimum mass is (8.3 +/- 0.3) Earth masses. This revision produces a significantly improved 5-planet Keplerian fit for 55 Cnc, and a self-consistent dynamical fit describes the data just as well. As radial velocity techniques push to ever-smaller planets, often found in systems of multiple planets, distinguishing true periods from aliases will become increasingly important.

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