标题： 哈勃空间望远镜上宽视场相机对超级地球GJ1214b的平坦传输光谱 显示英文标题

标题： The Flat Transmission Spectrum of the Super-Earth GJ1214b from Wide Field Camera 3 on the Hubble Space Telescope

摘要： 利用其红矮星宿主的观测优势，我们展示了HST/WFC3光栅对超级地球系外行星GJ1214b的传输光谱的测量结果。 这些是首次发表的WFC3对凌日系外行星大气的观测结果。 在纠正了类似斜坡的仪器系统误差后，我们在这些观测中实现了接近光子限制的精度，发现GJ1214b的传输光谱在1.1到1.7微米之间是平坦的。 与8.2倍标准差的无云太阳成分大气不一致，测量的色散凌日深度最可能意味着GJ1214b的外层包层具有较大的平均分子量。 致密的大气排除了通过围绕行星的非常低密度气体层来解释其大半径的总体成分。 高空云层可以另一种方式解释平坦的传输光谱，但它们需要在10毫巴或更高处光学厚度较大，或者由尺寸接近1微米的颗粒组成。 显示英文摘要

摘要： Capitalizing on the observational advantage offered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7 microns. Inconsistent with a cloud-free solar composition atmosphere at 8.2 sigma, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 micron in diameter.