The high occurrence rates of spiral arms and large central clearings in protoplanetary disks, if interpreted as signposts of giant planets, indicate that gas giants form commonly as companions to young stars ($ 10$\, Myr) have yielded few successes. This discrepancy could be explained if most giant planets form "cold start," i.e., by radiating away much of their formation energy as they assemble their mass, rendering them faint enough to elude detection at later times. In that case, giant planets should be bright at early times, during their accretion phase, and yet forming planets are detected only rarely through direct imaging techniques. Here we explore the possibility that the low detection rate of accreting planets is the result of episodic accretion through a circumplanetary disk. We also explore the possibility that the companion orbiting the Herbig Ae star HD~142527 may be a giant planet undergoing such an accretion outburst.

中文翻译：

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行星光度问题：“失踪的行星”和情节吸积的观测后果

原行星盘中旋臂和大型中央空地的高出现率，如果被解释为巨行星的路标，表明气态巨行星通常作为年轻恒星的伴星形成（$10$\，Myr）几乎没有取得成功。如果大多数巨行星形成“冷启动”，即通过在组装质量时辐射掉大部分形成能量，使它们变得足够暗以逃避以后的检测，则可以解释这种差异。在这种情况下，巨行星在吸积阶段的早期应该是明亮的，但是通过直接成像技术很少检测到正在形成的行星。在这里，我们探讨了吸积行星的低检测率可能是通过环行星盘进行的偶发吸积的结果。