太阳系外行星的多波段测光及其大气性质的研究

The study of the atmospheres of extra-solar planets, including their chemical composition and thermal structure, is one of the the hottest area, and is of great astrophysical importance. However, there are only few exoplanets with their atmospheres studied, most of which were done with space facilities like Hubble Space Telescope (HST) and Spitzer Space Telescope (SST). Therefore, we began a program to study exoplanetary atmospheres using multi-band photometry, with the 7 band optical imager GROND mounted at ESO/MPG 2.2m telescope, and the near-infrared camera WirCAM on CFHT. We have observed in total three planetary systems during their secondary eclipses. With detailed and careful data analysis, we expect to measure the secondary eclipse depth in various bands, to determine the thermal emission and temperature of the planets, and their characteristics like the abundances of CH4, CO2 and H20, and the presences of the thermal inversion layer and haze. We try the first attempt to study the atmospheres of exoplanets with ground-based small telescope, if succeed, should open a new aspect of the observations of exoplanets, and enhance the research of exoplanets in China. The diversity of the planetary systems may help to reveal the physical connection between planetary atmospheres and the planets and their host stars.

在太阳系外行星研究中，行星大气的研究，包括大气化学组成、温度结构等是当前最活跃也最有天体物理学意义的课题之一。受观测条件的限制，目前有仅有不到10颗系外行星其大气被研究过，且绝大部分都是利用空间望远镜HST或者Spitzer来完成。我们开展了利用地面小型望远镜多波段测光方法来研究系外行星大气的项目。我们申请欧南台/马普所2.2米望远镜的7波段成像仪GROND观测了2个系外行星系统，随后用CFHT的WirCAM近红外相机观测了1个系外行星系统。我们期待通过数据分析，测定行星在不同波段的次食深度，从而确定其热辐射率和热温度。利用现有大气模型构建理论光谱，与观测对比能确定类木热行星的大气温度结构和化学丰度，包括甲烷，二氧化碳甚至水分子的丰度及逆温层的存在等等。这是国际上是首次利用地面小型望远镜开展行星大气研究的工作。如果本项目获得成功，将产出有显示度的科研成果，并将促进国内外系外行星的发展。

基于我们利用CFHT3.5米望远镜的宽视场近红外相机WIRCam、马普所/欧南台2.2米望远镜等设备获得的高质量数据，我们完成了一系列系外行星的大气性质的研究工作。首先探测到了WASP-43b的宽带透射食深和热辐射食深，结合大气模型和其它数据，分析了它们的大气的物理和化学性质。我们还在2011年月食的时候，利用国台兴隆观测站2.16米望远镜获得了高分辨率、高信噪比的光谱，结合的确大气模型，测量了一系列的重要的分子的柱密度，为将来研究太阳系外类第行星大气提供了重要依据。我们还测量了类海王星行Kepler20c的主食在Ks波段的食深，将与其在光学波段Kp和中红外波段3.5微米的食深对比，从而进一步研究其性质。在项目执行的3年中，发表相关SCI论文4篇，会议文集1篇。