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arXiv 0705.0003astro-ph
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XO-2b:富金属共同自行双星中的热木星凌日

XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary

Christopher J. Burke, P. R. McCullough, Jeff A. Valenti, Christopher M. Johns-Krull, Kenneth A. Janes, J. N. Heasley, F. J. Summers, J. E. Stys, R. Bissinger, M… 展开作者

Christopher J. Burke, P. R. McCullough, Jeff A. Valenti, Christopher M. Johns-Krull, Kenneth A. Janes, J. N. Heasley, F. J. Summers, J. E. Stys, R. Bissinger, Michael L. Fleenor, Cindy N. Foote, Enrique Garcia-Melendo, Bruce L. Gary, P. J. Howell, F. Mallia, G. Masi, B. Taylor, T. Vanmunster

摘要:

我们报告了一颗V=11.2的早期K矮星XO-2(GSC 03413-00005),它拥有一颗Rp=0.98+0.03/-0.01 Rjup,Mp=0.57+/-0.06 Mjup的凌日系外行星XO-2b,轨道周期为2.615857+/-0.000005天。XO-2有高金属丰度,[Fe/H]=0.45+/-0.02,高自行,mu_tot=157 mas/yr,并有一个共同的自行伴星,距离为31”。这两颗恒星几乎是同卵双胞胎,光谱和视星等非常相似。由于高金属丰度,这些早期K矮星的质量和半径接近太阳,Ms=0.98+/-0.02 Msolar和Rs=0.97+0.02/-0.01 Rsolar。XO-2的高自行是由于其偏心轨道(银河系近心,Rper<4 kpc)被很好地限制在银河系盘面(Zmax~100 pc)内。此外,XO-2的相空间位置靠近武仙座动力流,这表明XO-2起源于富含金属的内部薄盘,随后动态散射到太阳附近。我们描述了一个有效的马尔可夫链蒙特卡罗算法计算贝叶斯后验概率的系统参数从过境光变曲线。

英文摘要:

We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has a common proper motion stellar companion with 31" separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, Ms=0.98+/-0.02 Msolar and Rs=0.97+0.02/-0.01 Rsolar. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4 kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner Thin Disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov Chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve.

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