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arXiv 0905.4680astro-ph.EP
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系外行星系统TrES-3九个RISE光变曲线的transit定时分析

A transit timing analysis of nine RISE light curves of the exoplanet system TrES-3

N. P. Gibson, D. Pollacco, I. Skillen, E. K. Simpson, S. Barros, Y. C. Joshi, I. Todd, C. Benn, D. Christian, M. Hrudková, F. P. Keenan, I. A. Steele

摘要:

我们提出了九个新观察到的过境的TrES-3,作为过境计时计划的一部分,使用上升仪器的利物浦望远镜。用马尔可夫链Monte-Carlo方法计算了该系统的行星-恒星半径比和倾角,得到的结果分别为Rp/Rstar=0.1664^{+0.0011}-0.0018}和i = 81.73^{+0.13}-0.04},与前人的结果一致。中心渡越时间和不确定性也计算,使用残差排列算法作为对误差的独立检查。重新分析了8个先前发表的TrES-3光变曲线,以确定渡越时间和不确定性使用一致的技术。虽然发现凌日时间与线性星历表不一致,15个自由度的x ^2 = 35.07,但我们认为这是光变曲线系统学的结果,而不是真正的凌日时间变化。这是因为光变曲线显示出与恒定周期的最大偏差,或者具有相对较少的过境覆盖范围,或者具有明确的系统性。利用这些渡越时间计算了新的星历,其结果为T_c(0)= 2454632.62610 +- 0.00006 HJD,P = 1.3061864 +- 0.0000005天。过境时间,然后被用来放置作为一个潜在的扰动行星的周期比的函数的质量上限,表明我们的数据是足够敏感的内部和外部2:1共振探测亚地球质量的行星,假设额外的行星是在一个最初的圆形轨道。

英文摘要:

We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte-Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be Rp/Rstar=0.1664^{+0.0011}_{-0.0018} and i = 81.73^{+0.13}_{-0.04} respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving chi^2 = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a constant period either have relatively little out-of-transit coverage, or have clear systematics. A new ephemeris was calculated using the transit times, and was found to be T_c(0) = 2454632.62610 +- 0.00006 HJD and P = 1.3061864 +- 0.0000005 days. The transit times were then used to place upper mass limits as a function of the period ratio of a potential perturbing planet, showing that our data are sufficiently sensitive to have probed for sub-Earth mass planets in both interior and exterior 2:1 resonances, assuming the additional planet is in an initially circular orbit.

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