标题： APOSTLE 对 GJ 1214b 的观测：系统参数和恒星活动的证据 显示英文标题

标题： APOSTLE Observations of GJ 1214b: System Parameters and Evidence for Stellar Activity

摘要： 我们展示了GJ 1214b的三次凌日事件，这些事件是作为阿波罗点天文台系外行星凌日光曲线调查（APOSTLE）的一部分进行观测的。我们使用了APOSTLE的r波段光曲线，并结合之前收集的GJ 1214b的数据重新推导了系统参数。通过使用诸如凌日持续时间和入射/出射长度等参数，我们能够减少拟合凌日模型中参数之间的退化情况，这对于通常用于量化测量参数不确定性的马尔可夫链蒙特卡罗技术来说是一种理想条件。对这个多波长数据集的联合分析确认了先前估计的系统参数，包括行星轨道周期、行星与恒星半径比和恒星密度。我们拟合了GJ 1214的光度光谱能量分布以推导恒星光度，然后利用它来推导其绝对质量和半径。从这些推导出的恒星特性以及之前发表的径向速度数据，我们能够改进对行星GJ 1214b的绝对参数的估计。我们研究得出的凌日时间没有显示出强烈的凌日时间变化的证据。我们提出的一些光曲线显示出我们认为是由于恒星活动引起的特征。在第一晚，我们观察到GJ 1214的非掩食通量上升，呈现出与恒星耀斑常见的快速上升指数衰减形状。在第二晚，我们在凌日过程中观察到一次轻微的增亮，我们认为这可能是由于行星遮挡了恒星盘上的星斑所致。 显示英文摘要

摘要： We present three transits of GJ 1214b, observed as part of the Apache Point Observatory Survey of Transit Lightcurves of Exoplanets (APOSTLE). We used APOSTLE r-band lightcurves in conjunction with previously gathered data of GJ 1214b to re-derive system parameters. By using parameters such as transit duration and ingress/egress length we are able to reduce the degeneracies between parameters in the fitted transit model, which is a preferred condition for Markov Chain Monte Carlo techniques typically used to quantify uncertainties in measured parameters. The joint analysis of this multi-wavelength dataset confirms earlier estimates of system parameters including planetary orbital period, the planet-to-star radius ratio and stellar density. We fit the photometric spectralenergy distribution of GJ 1214 to derive stellar luminosity, which we then use to derive its absolute mass and radius. From these derived stellar properties and previously published radial velocity data we were able to refine estimates of the absolute parameters for the planet GJ 1214b. Transit times derived from our study show no evidence for strong transit timing variations. Some lightcurves we present show features that we believe are due to stellar activity. During the first night we observed a rise in the out-of-eclipse flux of GJ 1214 with a characteristic fast-rise exponential decay shape commonly associated with stellar flares. On the second night we observed a minor brightening during transit, which we believe might have been caused by the planet obscuring a star-spot on the stellar disk.