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arXiv 1011.2144astro-ph.EP
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关于围绕活动恒星运行的超级地球情况下的行星质量测定。CoRoT-7系统的情况

On planetary mass determination in the case of super-Earths orbiting active stars. The case of the CoRoT-7 system

S. Ferraz-Mello, M. Tadeu dos Santos, C. Beauge, T. A. Michtchenko, A. Rodriguez

摘要:

这项研究使用了CoRoT-7出色的HARPS径向速度测量来重新确定行星质量,并探索能够确定活跃恒星周围发现的行星质量和元素的技术,因为恒星活动导致的径向速度的相对变化不能被认为只是噪音,并且可能超过行星的变化。此处使用的主要技术是Queloz等人(2009年)在CoRoT-7 b和CoRoT-7 c的首次质量测定中使用的高通滤波器的自洽版本。将结果与两种替代技术给出的结果进行比较:(1)Hatzes等人(2010)提出的方法,仅使用那些进行2或3次观测的夜晚;(2)纯傅立叶分析。在所有情况下,如系统潮汐演变研究所示,离心率取为零;周期也保持固定在Queloz等人给出的值上。仅使用在时间间隔BJD 2,454,847 - 873中进行的观测,因为它们包括许多夜晚的多次观测;否则,不可能将旋转四次谐波(5.91 d = Prot/4)的影响与CoRoT-7 b的轨道周期(0.853585 d)的混叠分开。综合各种方法的结果,得出CoRoT-7 b的行星质量值为8.0 \pm 1.2 MEarth,CoRoT-7 c的行星质量值为13.6 \pm 1.4 MEarth。本文还估计了恒星径向速度随其活动的变化,用三种不同的方法得到的结果都比以前的结果大。根据现有的内部结构模型,他们表明CoRoT-7 b是一个密度更大的超级地球。堆积密度为11 \pm 3.5 g.cm-3。CoRoT-7 b可能是岩石,有一个大的铁核心。

英文摘要:

This investigation uses the excellent HARPS radial velocity measurements of CoRoT-7 to re-determine the planet masses and to explore techniques able to determine mass and elements of planets discovered around active stars when the relative variation of the radial velocity due to the star activity cannot be considered as just noise and can exceed the variation due to the planets. The main technique used here is a self-consistent version of the high-pass filter used by Queloz et al. (2009) in the first mass determination of CoRoT-7b and CoRoT-7c. The results are compared to those given by two alternative techniques: (1) The approach proposed by Hatzes et al. (2010) using only those nights in which 2 or 3 observations were done; (2) A pure Fourier analysis. In all cases, the eccentricities are taken equal to zero as indicated by the study of the tidal evolution of the system; the periods are also kept fixed at the values given by Queloz et al. Only the observations done in the time interval BJD 2,454,847 - 873 are used because they include many nights with multiple observations; otherwise it is not possible to separate the effects of the rotation fourth harmonic (5.91d = Prot/4) from the alias of the orbital period of CoRoT-7b (0.853585 d). The results of the various approaches are combined to give for the planet masses the values 8.0 \pm 1.2 MEarth for CoRoT-7b and 13.6 \pm 1.4 MEarth for CoRoT 7c. An estimation of the variation of the radial velocity of the star due to its activity is also given.The results obtained with 3 different approaches agree to give masses larger than those in previous determinations. From the existing internal structure models they indicate that CoRoT-7b is a much denser super-Earth. The bulk density is 11 \pm 3.5 g.cm-3 . CoRoT-7b may be rocky with a large iron core.

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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