Young transiting planets

目前尚不清楚质量巨大的气态巨行星是由直接引力坍塌(收缩)形成的，还是首先由尘埃凝结和固体核心缓慢增长(生长)形成的，然后吸积成大气层；或者这两种途径是否都可能。行星形成的时间尺度也尚不清楚，例如在Myr内快速(通过直接引力崩塌)或在数十至数百Myr内缓慢(通过尘埃凝聚)。我们计划测量年轻行星的半径和平均密度-只有通过凌日技术才能直接实现。在所有凌日行星中(www.exoPlanet.eu)，到目前为止，没有一颗行星的年龄小于几百英里。我们计划继续并完成我们寻找年轻凌日行星的计划：我们在年轻的星系团25 Ori中发现了一个非常有希望的候选者，我们现在想通过进一步的后续观测来确认它是最年轻的凌日行星。预期的结果将使我们能够为不同的形成情景(以及行星形成的时间尺度)提供约束，从而使我们能够更好地了解行星形成过程的一般情况。

It is still not clear whether massive gas giant planets form by direct gravitational collapse (contracting) or first by dust coagulation and slow growth of a solid core (growing), then accreting an atmosphere; or whether both paths are possible. The time-scale of planet formation is also not yet known, e.g. fast within Myr (by direct gravitational collapse) or slow in tens to hundreds of Myr (by dust coagulation).We plan to measure radii and mean densities of young planets - possible in a direct way only with the transit technique.Among all transiting planets know so far (www.exoplanet.eu), none is younger than a few hundred Myr.We plan to continue and finish our project to search for young transit planets:We found a very promising candidate in the young cluster 25 Ori, for which we now would like to finish confirmation as youngest transit planet by further follow-up observations. The expected results would enable us to give constraints for different formation scenarios (and the planet formation time-scale) and, thus, lead to a better understanding of planetary formation processes in general.