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arXiv 1109.3203astro-ph.EP
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XX。CoRoT-20b:一个非常高密度,高离心率的过境巨行星

XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet

M. Deleuil, A. S. Bonomo, S. Ferraz-Mello, A. Erikson, F. Bouchy, M. Havel, S. Aigrain, J. -M. Almenara, R. Alonso, M. Auvergne, A. Baglin, P. Barge, P. Bordé, … 展开作者

M. Deleuil, A. S. Bonomo, S. Ferraz-Mello, A. Erikson, F. Bouchy, M. Havel, S. Aigrain, J. -M. Almenara, R. Alonso, M. Auvergne, A. Baglin, P. Barge, P. Bordé, H. Bruntt, J. Cabrera, S. Carpano, C. Cavarroc, Sz. Csizmadia, C. Damiani, H. J. Deeg, R. Dvorak, M. Fridlund, G. Hébrard, D. Gandolfi, M. Gillon, E. Guenther, T. Guillot, A. Hatzes, L. Jorda, A. Léger, H. Lammer, T. Mazeh, C. Moutou, M. Ollivier, A. Ofir, H. Parviainen, D. Queloz, H. Rauer, A. Rodríguez, D. Rouan, A. Santerne, J. Schneider, L. Tal-Or, B. Tingley, J. Weingrill, G. Wuchterl

摘要:

我们报告了CoRoT太空任务发现的一颗新的巨行星CoRoT-20 b。该行星的质量为4.24 +/- 0.23 MJ,半径为0.84 +/- 0.04 RJ。它的平均密度为8.87 +/- 1.10 g/cm^3,是迄今为止已知最紧凑的行星之一。行星的演化模型表明,如果嵌入中央核心,重元素的质量约为800 ME,需要对行星形成模型或行星演化和结构模型进行修订。然而,我们注意到,从更现实的模型中,预计会有更少量的重元素,在这些模型中,它们在整个包层中混合。这颗行星围绕一颗G型恒星运行,轨道周期为9.24天,离心率为0.56。这颗恒星的预计自转速度为vsini = 4.5 +/- 1.0 km/s,如果它的自转轴垂直于轨道平面,则自转周期为11.5 +/- 3.1天。在达尔文理论的框架下,忽略恒星的磁场破坏,我们计算了系统的潮汐演化,并表明CoRoT-20 b是目前为数不多的达尔文稳定的行星之一,正在朝着三重同步状态发展,轨道,行星和恒星的自旋周期相等。

英文摘要:

We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 +/- 0.23 MJ and a radius of 0.84 +/- 0.04 RJ. With a mean density of 8.87 +/- 1.10 g/cm^3, it is among the most compact planets known so far. Evolution models for the planet suggest a mass of heavy elements of the order of 800 ME if embedded in a central core, requiring a revision either of the planet formation models or of planet evolution and structure models. We note however that smaller amounts of heavy elements are expected from more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56. The star's projected rotational velocity is vsini = 4.5 +/- 1.0 km/s, corresponding to a spin period of 11.5 +/- 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving towards a triple synchronous state with equality of the orbital, planetary and stellar spin periods.

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