标题： 利用盖亚视差估计单一过境K2行星周期 显示英文标题

标题： Estimation of singly-transiting K2 planet periods with Gaia parallaxes

摘要： 当一颗行星仅被观测到发生一次凌星时，直接测量其周期是不可能的。然而，有可能限制单次凌星行星的周期，并且这是可取的，因为它们很可能代表了特定调查中观测到的行星群体中的寒冷和遥远的极端情况。因此，提高限制单次凌星行星周期的准确性对于增强调查的长周期行星产量至关重要。 在这里，我们将盖亚视差与恒星模型和宽波段测光结合，估算K2系外行星宿主恒星的密度，然后利用这些恒星密度信息来模拟单个行星凌星并推断后验周期分布。 我们通过与通过星震学推导的密度进行比较，证明我们推断出的密度是可靠的，并将我们的方法应用于27颗已知（直接测量）周期的验证行星（将其每次凌星都当作唯一的），以及12颗真正的单次凌星行星。 当我们将偏心率作为一个自由参数时，我们实现了相对于真实单次凌星的周期不确定度为$94^{+87}_{-58}\%$；而当我们固定$e=0$时，我们实现了周期不确定度$15^{+30}_{-6}\%$，这比以往研究中的典型周期不确定度提高了大约三倍。 显示英文摘要

摘要： When a planet is only observed to transit once, direct measurement of its period is impossible. It is possible, however, to constrain the periods of single transiters, and this is desirable as they are likely to represent the cold and far extremes of the planet population observed by any particular survey. Improving the accuracy with which the period of single transiters can be constrained is therefore critical to enhance the long-period planet yield of surveys. Here, we combine Gaia parallaxes with stellar models and broad-band photometry to estimate the stellar densities of K2 planet host stars, then use that stellar density information to model individual planet transits and infer the posterior period distribution. We show that the densities we infer are reliable by comparing with densities derived through asteroseismology, and apply our method to 27 validation planets of known (directly measured) period, treating each transit as if it were the only one, as well as to 12 true single transiters. When we treat eccentricity as a free parameter, we achieve a fractional period uncertainty over the true single transits of $94^{+87}_{-58}\%$, and when we fix $e=0$, we achieve fractional period uncertainty $15^{+30}_{-6}\%$, a roughly threefold improvement over typical period uncertainties of previous studies.