Direct detection of Jovian planets around young solar analogs and their atmospheres

目前尚不清楚我们的太阳系与其他行星系统相比有多频繁和典型。径向速度搜索主要是对早期类太阳的G型恒星进行的，但几乎只有正常的主序恒星被观测到，并且只有接近的大质量行星(最多几个AU，超过几个地球质量)可以通过径向速度搜索来探测到。在这个新的项目中，我们计划搜索年轻恒星(最多10 Myr)周围的大质量行星(大约一半木星质量或更多)，一旦它们进入主序，它们将成为类似太阳的恒星。通过自适应光学和大型望远镜的直接成像，我们可以发现所有质量约为10AU的行星。一旦候选行星被证实是共同运动和围绕恒星运行的，我们将在红外中获取它们的大气光谱。然后，我们将把这些光谱与模型大气进行比较，例如最近的漂移-凤凰网(Witte，Hling&Hausschilt)，以确定金属丰度、重力、温度、半径等物理参数，从而确定质量。除了搜索和观测年轻恒星周围的行星外，我们还计划改进模型大气。质量估算最关键的参数是重力。因此，必须改进模式大气，以便从整体(准)连续体形状和单独的重力敏感线精确确定重力成为可能。要做到这一点，必须考虑到更好的(剖面)线数据，再加上尘埃云的形成。此外，模型网格中覆盖的参数空间必须扩大(包括质量较小的行星，因此温度较低的行星)，并且必须以更高的参数分辨率计算网格，以便在系统误差内确定最佳参数。我们可以使用年轻的类日恒星周围的年轻大质量行星的样本来研究我们的太阳系有多典型，并限制其形成情景。该项目是观察者和理论家之间的密切合作，也应该在太阳系外行星和太阳系行星之间建立密切联系。

It is not yet clear how frequent and typical our solar system is compared to other planetary systems. Radial velocity searches have been carried out mostly for solar-like early G-type stars, but almost only normal main sequence stars were observed and only close-in massive planets (up to few AU, more than a few Earth masses) can be detected by radial velocity searches.In this new project, we plan to search for massive planets (about half a Jupiter mass and more) around young stars (up to 10 Myrs), which will become solar analog stars once they are on the main sequence. By direct imaging with Adaptive Optics and large telescopes, we can find all massive planets upside of about ~ 10 AU.Once planet candidates are confirmed to be co-moving and orbiting the star, we will take spectra of their atmospheres in the infrared. We will then compare those spectra with model atmospheres such as most recent DRIFT-PHOENIX grid (Witte, Helling & Hauschildt) in order to determine physical parameters such as metallicity, gravity, temperature, radius and, hence, mass.In addition to the search and observation of planets around young stars, we also plan to improve the model atmospheres. The most critical parameter for mass estimation is the gravity. Hence, the model atmospheres have to be improved, so that the precise determination of gravities from both the overall (quasi-) continuum shape and the individual gravity-sensitive lines becomes feasible. For doing so, much better (profile) line data have to be taken into account, coupled to the formation of dust clouds. Also, the parameter space covered in the model grids has to be enlarged (to include less massive and thus cooler planets) and the grid has to be computed with higher parameter resolution for an optimum parameter determination inside the systematic errors.We can use the sample of young massive planets around young solar analog stars to investigate how typical our solar system is and to constrain its formation scenario. This project is a close collaboration between observers and theorists and should also establish a close link between extra-solar planets and solar system planets.