HUBBLE SPACE TELESCOPE OBSERVATIONS OF THE NUV TRANSIT OF WASP-12b
HUBBLE SPACE TELESCOPE OBSERVATIONS OF THE NUV TRANSIT OF WASP-12b
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WASP-12b NUV 凌日的哈勃太空望远镜观测
DOI：
10.1088/0004-637x/803/1/9
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
D. Bisikalo
中科院分区：
文献类型：
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作者：
Jonathan D. Nichols;Graham A. Wynn;M. R. Goad;Richard D. Alexander;S. Casewell;S. W. H. Cowley;M. Burleigh;John Clarke;D. Bisikalo
我们提出了四个紧密间隔的近紫外线（NUV）的热类星体的系外行星WASP-12 b使用哈勃太空望远镜（HST）/宇宙起源光谱仪（COS）的新的观测，显着增加所观察到的NUV光变曲线相对于以前的观测的相位分辨率，同时最大限度地减少系统的时间变化。我们观察到显着过量NUV吸收过境期间，平均归一化过境通量的F规范<$0.97？>，也就是，什么？>比光学渡越能级φ 0.986？对于均匀的恒星盘（确切的置信水平取决于所使用的归一化方法）。我们进一步观察到一个不对称的过境形状，这样的后结合通量是整体？>比汇合前值高2-3σ，并以汇合前和运输外水平之间计数率的快速变化为特征。我们没有发现早期进入NUV过境的证据所建议的早期HST观测。然而，我们表明，NUV计数率观察之前的光学过境是高度可变的，但总体上？>低于后过境值2.2-3.0σ，深度与光学过境相当，可能形成一个NUV吸收的可变区域，至少从相位φ <0.83？>受数据覆盖面的限制。
We present new observations of four closely spaced near-ultraviolet (NUV) transits of the hot Jupiter-like exoplanet WASP-12b using Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS), significantly increasing the phase resolution of the observed NUV light curve relative to previous observations, while minimizing the temporal variation of the system. We observe significant excess NUV absorption during the transit, with mean normalized in-transit fluxes of F norm ≃ 0.97 ?> , i.e., ≃ ?> 2–5σ deeper than the optical transit level of ≃ 0.986 ?> for a uniform stellar disk (the exact confidence level depending on the normalization method used). We further observe an asymmetric transit shape, such that the post-conjunction fluxes are overall ≃ ?> 2–3σ higher than pre-conjunction values, and characterized by rapid variations in count rate between the pre-conjunction and out-of-transit levels. We do not find evidence for an early ingress to the NUV transit as suggested by earlier HST observations. However, we show that the NUV count rate observed prior to the optical transit is highly variable, but overall ≃ ?> 2.2–3.0σ below the post-transit values and comparable in depth to the optical transit, possibly forming a variable region of NUV absorption from at least phase φ ≃ 0.83 ?> , limited by the data coverage.