Planets around evolved binary systems

从观测到的3000多个白矮星加主序(WDMS)系统中，到目前为止，已知200多个后公共包络双星(PCEB)。这种后公共包络双星(PCEB)不仅本身就是令人兴奋的物体，而且还可能在它们周围藏匿着行星。迄今为止，一些PCEB系统已经为行星的存在提供了证据，尽管它们进行了猛烈的动力学演化。目前，研究最多也是最确定的情况是NN Ser，它的日食时序变化可以通过一个行星系统的存在来解释，该行星系统由两颗质量较大的木星组成，大约有7和2 MJup，分别以3 AU和5 AU的距离围绕它们的宿主双星运行。然而，目前还不清楚这些行星是如何形成的。原则上，这些围绕PCEB运行的行星可以与双星一起形成，即作为第一代(FG)行星，也可以在CE阶段之后形成，作为第二代(SG)行星。在这里，我们将用三维流体动力学模拟来研究这两种情况，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.