SPIRou的早期科学：行星宿主恒星HD 189733的近红外径向速度和分光偏振测量
Early science with SPIRou: near-infrared radial velocity and spectropolarimetry of the planet-hosting star HD 189733
摘要：
SPIRou是最近安装在夏威夷Maunakea的加拿大-法国-夏威夷望远镜上的最新分光偏振计和高精度速度计。它工作在近红外，同时以高光谱分辨率覆盖0.98-2.35 μm区域。SPIRou是优化的系外行星搜索和表征的径向速度技术，并在恒星线和随后的磁场研究的偏振测量。凌日热木星HD 189733 b的宿主在早期的科学运行中被观测到。我们提出了第一个近红外光谱偏振观测的行星托管恒星以及恒星径向速度测量的SPIRou整个行星轨道和两个过境序列。对行星轨道和Rossiter-McLaughlin异常进行了研究和模拟。的轨道参数和结晶度都是兼容的光学中发现的值。在这些条件下，所获得的径向速度精度与K2星的光子噪声估计的大约两倍兼容。轨道周围的额外散射约为8米/秒，与以前的结果一致，表明活动引起的散射是主导因素。我们分析了偏振信号，塞曼展宽，色球活动示踪剂，如1083 nm氦和1282 nm Pa \b{eta}线调查恒星活动。根据FeI谱线的塞曼展宽对平均无符号磁通量的初步估计给出了290 ± 58 G的磁通量，大尺度纵向场显示出几个高斯的典型值。这些观测结果说明了SPIRou在系外行星特征描述以及磁性和恒星活动研究方面的潜力。
英文摘要：
SPIRou is the newest spectropolarimeter and high-precision velocimeter that has recently been installed at the Canada-France-Hawaii Telescope on Maunakea, Hawaii. It operates in the near-infrared and simultaneously covers the 0.98-2.35 μm domain at high spectral resolution. SPIRou is optimized for exoplanet search and characterization with the radial-velocity technique, and for polarization measurements in stellar lines and subsequent magnetic field studies. The host of the transiting hot Jupiter HD 189733 b has been observed during early science runs. We present the first near-infrared spectropolarimetric observations of the planet-hosting star as well as the stellar radial velocities as measured by SPIRou throughout the planetary orbit and two transit sequences. The planetary orbit and Rossiter-McLaughlin anomaly are both investigated and modeled. The orbital parameters and obliquity are all compatible with the values found in the optical. The obtained radial-velocity precision is compatible with about twice the photon-noise estimates for a K2 star under these conditions. The additional scatter around the orbit, of about 8 m/s, agrees with previous results that showed that the activity-induced scatter is the dominant factor. We analyzed the polarimetric signal, Zeeman broadening, and chromospheric activity tracers such as the 1083nm HeI and the 1282nm Pa\b{eta} lines to investigate stellar activity. First estimates of the average unsigned magnetic flux from the Zeeman broadening of the FeI lines give a magnetic flux of 290+-58 G, and the large-scale longitudinal field shows typical values of a few Gauss. These observations illustrate the potential of SPIRou for exoplanet characterization and magnetic and stellar activity studies.
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