Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system
Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system
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DOI：
10.1051/0004-6361/202038703
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发表时间：
2020-07
影响因子：
6.5
通讯作者：
R. Luque;N. Casasayas-Barris;H. Parviainen;Guo Chen;E. Pallé;J. Livingston;V. Béjar;N. Crouzet-N.-Crou
中科院分区：
文献类型：
--
作者：
R. Luque;N. Casasayas-Barris;H. Parviainen;Guo Chen;E. Pallé;J. Livingston;V. Béjar;N. Crouzet-N.-Crou
我们提出了新的过境观测热木星WASP-74 B（$T_\mathrm{eq} \sim $1860 K）使用高分辨率光谱仪HARPS-N和多色同时成像仪MuSCAT 2。我们改进了行星和它的宿主星星的轨道特性，并首次测量了它的轨道。测量到的恒星自转轴和行星轨道轴之间的天空投影角与主星星赤道的轨道一致（$\lambda = 0.77\pm0.99 \mathrm{deg}$）。我们无法检测到H$\alpha$的任何吸收特征，或任何其他原子光谱特征，在其高分辨率的透射光谱由于低S/N线核心。尽管先前的声明中关于存在强的光学吸收剂，如TiO和VO气体在大气中的WASP-74 B，新的地面测光结合重新分析以前报道的观察文献显示，在低分辨率透射光谱的斜率比预期的更陡峭，从瑞利散射单独。
We present new transit observations of the hot Jupiter WASP-74 b ($T_\mathrm{eq} \sim$ 1860 K) using the high-resolution spectrograph HARPS-N and the multi-colour simultaneous imager MuSCAT2. We refine the orbital properties of the planet and its host star, and measure its obliquity for the first time. The measured sky-projected angle between the stellar spin-axis and the planet's orbital axis is compatible with an orbit well-aligned with the equator of the host star ($\lambda = 0.77\pm0.99 \mathrm{deg}$). We are not able to detect any absorption feature of H$\alpha$, or any other atomic spectral features, in its high-resolution transmission spectra due to low S/N at the line cores. Despite previous claims regarding the presence of strong optical absorbers such TiO and VO gases in the atmosphere of WASP-74 b, the new ground-based photometry combined with a reanalysis of previously reported observations from the literature shows a slope in the low-resolution transmission spectrum steeper than expected from Rayleigh scattering alone.