论文标题
苔丝已知系外行星的经验肢体式系数和过境参数
Empirical limb-darkening coefficients & transit parameters of known exoplanets from TESS
论文作者
论文摘要
尽管过渡系外行星调查卫星（\ textit {tess}）的主要目标是搜索新的过渡系外行星，但其数据也可用于进一步详细的已知系统研究。 \ textIt {tess} bandpass在研究恒星宿主的肢体变形效果上特别有趣，因为广泛使用的\ textsc {phoenix} {phoenix}和\ textsc {atlas} Stellar模型可预测不同的肢体模型。在这里，我们通过拟合\ textit {tess}观察到的176个已知外球星系统的过境光效率来研究这种效果，该系统使我们能够针对广泛使用的典型定律提取经验性的肢体销售系数（LDC），但也更新了epphemerides comprodements（包括Emprodements）。将我们的经验获得的LDC与理论预测进行比较，我们在使用列表\ textit {tess} ldcs时发现了重要的偏移。具体而言，使用\ textsc {phoenix}获得的$ u_2 $系数显示，根据用于得出它们的方法的最大差异，其偏移平均可以达到$ΔU_2\ after的偏移。但是，如果人们使用Howarth（2011）引入的垃圾邮件算法来计算LDCS，那么这些平均偏移中的大多数都会消失。但是，我们的结果表明，对于恒星比大约5000 K的恒星凉爽，没有足够好的方法来解释肢体变形的效果：我们观察到测量和预测的LDC之间对两个二次二次LDC $ΔU_1，ΔU_2，ΔU_2\ to to Cool Alter的二次LDC的偏差。我们建议在将肢体变形系数假定为完全已知时，特别是对于这些凉爽的恒星，分析\ textIt {tess} Transit Lightcurves时，请谨慎。
Although the main goal of the Transiting Exoplanet Survey Satellite (\textit{TESS}) is to search for new transiting exoplanets, its data can also be used to study in further detail already known systems. The \textit{TESS} bandpass is particularly interesting to study the limb-darkening effect of the stellar host which is imprinted in transit lightcurves, as the widely used \textsc{phoenix} and \textsc{atlas} stellar models predict different limb-darkening profiles. Here we study this effect by fitting the transit lightcurves of 176 known exoplanetary systems observed by \textit{TESS}, which allows us to extract empirical limb-darkening coefficients (LDCs) for the widely used quadratic law, but also updated transit parameters (including ephemerides refinements) as a byproduct. Comparing our empirically obtained LDCs with theoretical predictions, we find significant offsets when using tabulated \textit{TESS} LDCs. Specifically, the $u_2$ coefficients obtained using \textsc{phoenix} models show the largest discrepancies depending on the method used to derive them, with offsets that can reach up to $Δu_2 \approx 0.2$ on average. Most of those average offsets disappear, however, if one uses the SPAM algorithm introduced by Howarth (2011) to calculate the LDCs instead. Our results suggest, however, that for stars cooler than about 5000 K, no methodology is good enough to explain the limb-darkening effect: we observe a sharp deviation between measured and predicted LDCs on both quadratic LDCs of order $Δu_1, Δu_2 \approx 0.2$ for those cool stars. We recommend caution when assuming limb-darkening coefficients as perfectly known thus, in particular for these cooler stars when analyzing \textit{TESS} transit lightcurves.
