High precision radial velocity measurements in the infrared A first assessment of the RV stability of CRIRES
High precision radial velocity measurements in the infrared A first assessment of the RV stability of CRIRES
复制标题
红外高精度径向速度测量 CRIRES RV 稳定性的首次评估
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
H. Kaeufl
中科院分区：
文献类型：
--
作者：
A. Seifahrt;H. Kaeufl
近红外领域对高精度径向速度 (RV) 测量的需求很高，特别是在系外行星搜索活动将兴趣转向晚型恒星以探测质量越来越低的行星或瞄准嵌入的前主序天体的背景下。 ESO 在 VLT 上委托安装了一台新的光谱仪 – CRIRES – 专为高分辨率近红外光谱而设计，具有相对较宽的波长覆盖范围，并且可以使用气室提供稳定的 RV 零点。在这里，我们研究了 CRIRES 固有的短期 RV 稳定性，包括气室校准数据和使用源光谱中印记的地球大气吸收线作为本地 RV 静止框架的空中测量。此外，我们还首次研究了 4100 nm 处大地线的内在稳定性，以了解源自对流层低层的特征。我们对 MS Vel（一颗以 4100 nm 处两个 SiO 第一泛音带头为中心的 M2II 亮巨星）近 5 小时的连续观测进行的分析表明，CRIRES 的内在短期稳定性非常高，在 4.5 小时后仅显示出高达 60 m/s 的缓慢且完全可补偿的漂移。大地线的径向速度是恒定的，低至约。 ±10 m/ s（或一个像素的 7/1000）。利用相同的大地线作为静止坐标系来测量科学目标的径向速度，我们获得了恒定的 RV，精度约为。 MS Vel 为 ±20 m/s，正如 M 巨人所预期的那样。
High precision radial velocity (RV) measurements in the near infrared are in high demand, especially in the context of exoplanet search campaigns shifting their interest to late type stars in order to detect planets with ever lower mass or targeting embedded pre-main-sequence objects. ESO commissioned a new spectrograph at the VLT – CRIRES – designed for high resolution near-infrared spectroscopy with a comparably broad wavelength coverage and the possibility of using gascells to provide a stable RV zero-point. Here, we investigate the intrinsic short-term RV stability of CRIRES, both with gascell calibration data and on-sky measurements using the absorption lines of the Earth’s atmosphere imprinted in the source spectrum as a local RV rest frame. Moreover, we also investigate for the first time the intrinsic stability of telluric lines at 4100 nm for features originating in the lower troposphere. Our analysis of nearly 5 h of consecutive observations of MS Vel, a M2II bright giant centred on two SiO first overtone band-heads at 4100 nm, demonstrates that the intrinsic short-term stability of CRIRES is very high, showing only a slow and fully compensateable drift of up to 60 m/s after 4.5 h. The radial velocity of the telluric lines is constant down to a level of approx. ±10 m/ s( or 7/1000 of one pixel). Utilising the same telluric lines as a rest frame for our radial velocity measurements of the science target, we obtain a constant RV with a precision of approx. ±20 m/s for MS Vel, as expected for a M-giant.