The origin of the excess transit absorption in the HD 189733 system: planet or star?
The origin of the excess transit absorption in the HD 189733 system: planet or star?
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DOI：
10.1093/mnras/stw1713
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发表时间：
2016-07
影响因子：
4.8
通讯作者：
J. Barnes;C. Haswell;D. Staab;G. Anglada-Escudé
中科院分区：
文献类型：
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作者：
J. Barnes;C. Haswell;D. Staab;G. Anglada-Escudé
我们在CAII香港过境1)和0.0214±0.0022(9.8σ；过境2)的发射核心中检测到了过量吸收。类似地，我们在带宽为α=0.7A的通带中检测到过量的H-Δλ吸收，其Td=0.0084±0.0016(5.2σ)和0.0121±0.0012(9.9σ)。因此，对于这两条线路来说，交通2号线的深度都要大得多。将Na-I-D线的三条凌日相结合，得到超额吸收Td=0.0041±0.0006(6.5σ)。通过考虑每条谱线的时间序列观测，我们发现在恒星参考系中恢复过剩的表观吸收是最好的。这些发现使我们假设，在微分光曲线中产生超额渡越吸收的主要原因是归一化连续谱带在光球层中形成，而线芯包含色球成分。我们不能排除部分过量吸收信号来自行星大气，但我们提出的证据对最近在这些数据中探测到行星大气中的风运动的说法提出了质疑。
We have detected excess absorption in the emission cores of Ca II HK Transit 1) and 0.0214 ± 0.0022 (9.8σ; Transit 2). Similarly, we detect excess Hα absorption in a passband of width Δλ = 0.7 A, with td = 0.0084 ± 0.0016 (5.2σ) and 0.0121 ± 0.0012 (9.9σ). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of td = 0.0041 ± 0.0006 (6.5σ). By considering the time series observations of each line, we find that the excess apparent absorption is best recovered in the stellar reference frame. These findings lead us to postulate that the main contribution to the excess transit absorption in the differential light curves arises because the normalizing continuum bands form in the photosphere, whereas the line cores contain a chromospheric component. We cannot rule out that part of the excess absorption signature arises from the planetary atmosphere, but we present evidence which casts doubt on recent claims to have detected wind motions in the planet's atmosphere in these data.