Planets around evolved binary systems

从3000多个观测到的白色矮星加主序星（WDMS）系统中，到目前为止，已知有200多个后共包络双星（PCEB）。这种后共包络双星（PCEB）不仅本身是令人兴奋的物体，而且还可能在它们周围拥有行星。到目前为止，大量的PCEB系统已经提供了行星存在的证据，尽管它们的动力学演化非常剧烈。目前，研究最多，因此也是最确定的例子是NN Ser，它的日食时间变化可以用一个行星系统来解释，该系统由两颗质量约为7和2 MJup的木星行星组成，分别在3和5 Au的距离上绕着它们的宿主双星运行。目前还不清楚这些行星是如何形成的。原则上，这些环绕PCEB的行星可以与双星一起形成，即作为第一代（FG）行星，或者可以在CE阶段之后形成，作为第二代（SG）行星。在这里，我们将研究这两个方案与三维流体动力学模拟，包括N体相互作用。

From the more than 3000 observed white dwarf plus main-sequence (WDMS) systems, by now more than 200 post common envelope binaries (PCEBs) are known. Such post-common-envelope binaries (PCEBs) are not only exciting objects by themselves but could also harbour planets around them. To date, a handfull of PCEB systems have provided evidence for the presence of planets, despite their violent dynamical evolution. Currently, the most studied and hence most certain case is NN Ser, whose eclipse-timing variations can be explained by the presence of a planetary system consisting of two massive Jovian planets with roughly 7 and 2 MJup, orbiting their hosting binary at distances of 3 and 5 AU, respectively. Yet it is unclear how those planets are formed. In principle, such planets orbiting PCEBs can either form together with the binary, i.e. as first generation (FG) planets, or can be formed after the CE phase, as second generation (SG) planets. Here we will study both scenarios with three dimensional hydrodynamical simulations including N-body interaction.