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arXiv 1109.1561astro-ph.EP
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开普勒-19系统:一颗凌日2.2 R_地球行星和一颗通过Transit时间变化探测到的第二颗行星

The Kepler-19 System: A Transiting 2.2 R_Earth Planet and a Second Planet Detected via Transit Timing Variations

Sarah Ballard, Daniel Fabrycky, Francois Fressin, David Charbonneau, Jean-Michel Desert, Guillermo Torres, Geoffrey Marcy, Christopher J. Burke, Howard Isaacson… 展开作者

Sarah Ballard, Daniel Fabrycky, Francois Fressin, David Charbonneau, Jean-Michel Desert, Guillermo Torres, Geoffrey Marcy, Christopher J. Burke, Howard Isaacson, Christopher Henze, Jason H. Steffen, David R. Ciardi, Steven B. Howell, William D. Cochran, Michael Endl, Stephen T. Bryson, Jason F. Rowe, Matthew J. Holman, Jack J. Lissauer, Jon M. Jenkins, Martin Still, Eric B. Ford, Jessie L. Christiansen, Christopher K. Middour, Michael R. Haas, Jie Li, Jennifer R. Hall, Sean McCauliff, Natalie M. Batalha, David G. Koch, William J. Borucki

摘要:

我们提出了开普勒-19行星系的发现,我们首先确定了一个9.3天的周期性的过境信号在开普勒测光。从恒星的高分辨率光谱中,我们发现恒星有效温度Teff=5541 \pm 60 K,金属丰度[Fe/H]=-0.13 \pm 0.06,表面重力log(g)=4.59 \pm 0.10。我们结合Teff和[Fe/H]的估计值和由光度光变曲线得到的恒星密度的估计值,推导出恒星质量M_star = 0.936 \pm 0.040 M_Sun,恒星半径R_star = 0.850 \pm 0.018 R_Sun。我们排除了凌日的可能性,从一个天体物理的假阳性的结果,首先确定的恒星混合物的子集,再现光变曲线的精确形状。我们的结论是,行星的情况是超过三个数量级以上的可能性比混合。混合的情况是独立不利的消色差的过境:我们测量的过境深度与斯皮策在4.5 μm的547+113-110 ppm,与开普勒光学带通测量的深度567 \pm 6 ppm。我们确定行星Kepler-19 b的物理半径为R_p = 2.209 \pm 0.048 R_Earth。通过对该恒星径向速度的观测,我们发现行星质量的上限为20.3 M地球,对应的最大密度为10.4 g cm^-3。我们报告了一个显着的正弦偏差的过境时间从预测的线性星历,我们的结论是由于在系统中的一个额外的扰动体。我们不能唯一地确定扰动的轨道参数,因为各种动力学机制与过境定时信号的振幅、周期和形状相匹配,并满足宿主星的径向速度限制。然而,这些机制中的扰动周期<160天,质量<6 M_Jup,确认其行星性质为开普勒-19c。[摘要]

英文摘要:

We present the discovery of the Kepler-19 planetary system, which we first identified from a 9.3-day periodic transit signal in the Kepler photometry. From high-resolution spectroscopy of the star, we find a stellar effective temperature Teff=5541 \pm 60 K, a metallicity [Fe/H]=-0.13 \pm 0.06, and a surface gravity log(g)=4.59 \pm 0.10. We combine the estimate of Teff and [Fe/H] with an estimate of the stellar density derived from the photometric light curve to deduce a stellar mass of M_star = 0.936 \pm 0.040 M_Sun and a stellar radius of R_star = 0.850 \pm 0.018 R_Sun. We rule out the possibility that the transits result from an astrophysical false positive by first identifying the subset of stellar blends that reproduce the precise shape of the light curve. We conclude that the planetary scenario is more than three orders of magnitude more likely than a blend. The blend scenario is independently disfavored by the achromaticity of the transit: we measure a transit depth with Spitzer at 4.5 μm of 547+113-110 ppm, consistent with the depth measured in the Kepler optical bandpass of 567\pm6 ppm. We determine a physical radius of the planet Kepler-19b of R_p = 2.209 \pm 0.048 R_Earth. From radial-velocity observations of the star, we find an upper limit on the planet mass of 20.3 M_Earth, corresponding to a maximum density of 10.4 g cm^-3. We report a significant sinusoidal deviation of the transit times from a predicted linear ephemeris, which we conclude is due to an additional perturbing body in the system. We cannot uniquely determine the orbital parameters of the perturber, as various dynamical mechanisms match the amplitude, period, and shape of the transit timing signal and satisfy the host star's radial velocity limits. However, the perturber in these mechanisms has period <160 days and mass <6 M_Jup, confirming its planetary nature as Kepler-19c. [Abridged]

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