Light echoes of flares on active stars offer the opportunity for direct detection of circumstellar dust. We revisit the problem of identifying faint echoes in postflare light curves, focusing on debris disks from ongoing planet formation. Starting with simulations, we develop an algorithm for estimating the radial extent and total mass from disk echo profiles. We apply this algorithm to light curves from over 2100 stars observed by NASA’s Kepler mission, selected for multiple short-lived flares in either the long-cadence or short-cadence data sets. While flux uncertainties in light curves from individual stars preclude useful mass limits on circumstellar disks, catalog-averaged light curves yield constraints on disk mass that are comparable to estimates from known debris disks. The average mass in micron- to millimeter-sized dust around the Kepler stars cannot exceed 10% of an Earth mass in exo-Kuiper belts or 10%of a lunar mass in the terrestrial zone. We group stars according to IR excess, based on WISE W1–W3 color, as an indicator for the presence of circumstellar dust. The mass limits are greater for stars with strong IR excess, a hint that echoes are lurking not far beneath the noise in postflare light curves. With increased sensitivity, echo detection will let time-domain astronomy complement spectroscopic and direct-imaging studies in mapping how, when, and where planets form.

活动恒星上耀斑的光回波为直接探测星周尘埃提供了机会。我们重新审视了在耀斑后光曲线中识别微弱回声的问题，重点关注正在进行的行星形成过程中的碎片盘。从模拟开始，我们开发了一种算法，用于从磁盘回波剖面估计径向范围和总质量。我们将此算法应用于 NASA 开普勒任务观测到的 2100 多颗恒星的光变曲线，这些恒星是为长节奏或短节奏数据集中的多个短寿命耀斑选择的。虽然来自单个恒星的光变曲线的通量不确定性排除了对星周盘的有用质量限制，但目录平均光变曲线对盘质量的限制与已知碎片盘的估计值相当。开普勒恒星周围微米到毫米级尘埃的平均质量不能超过柯伊伯带外地球质量的 10% 或地球区域月球质量的 10%。我们根据 WISE W1-W3 颜色根据 IR 过量对恒星进行分组，作为星周尘埃存在的指标。具有强烈红外过剩的恒星的质量限制更大，这暗示回声潜伏在后耀斑光曲线噪声下不远的地方。随着灵敏度的提高，回波检测将使时域天文学补充光谱和直接成像研究，以绘制行星形成的方式、时间和地点。具有强烈红外过剩的恒星的质量限制更大，这暗示回声潜伏在后耀斑光曲线噪声下不远的地方。随着灵敏度的提高，回波检测将使时域天文学补充光谱和直接成像研究，以绘制行星形成的方式、时间和地点。具有强烈红外过剩的恒星的质量限制更大，这暗示回声潜伏在后耀斑光曲线噪声下不远的地方。随着灵敏度的提高，回波检测将使时域天文学补充光谱和直接成像研究，以绘制行星形成的方式、时间和地点。