Gaia Data Release 2
Gaia Data Release 2
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DOI：
10.1051/0004-6361/201832836
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发表时间：
2018-04
影响因子：
6.5
通讯作者：
P. Sartoretti;D. Katz;M. Cropper;P. Panuzzo;G. Seabroke;Y. Viala;K. Benson;R. Blomme;G.
中科院分区：
文献类型：
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作者：
P. Sartoretti;D. Katz;M. Cropper;P. Panuzzo;G. Seabroke;Y. Viala;K. Benson;R. Blomme;G.
上下文。盖亚数据发布2号（DR2）包含了第一次发布的径向速度，补充了大约700万颗相对明亮的晚型恒星样本的运动学数据。目标。本文详细描述了盖亚光谱数据处理管道，以及DR2中提出的径向速度的推导方法。方法。管道必须完成四项主要任务：(i)清理和减少径向速度光谱仪（RVS）观测到的光谱；（ii）校准RVS仪器，包括波长、杂散光、线扩展函数、偏置不均匀性和光度零点；（iii）提取径向速度；（iv）验证结果的准确性和精密度。恒星的径向速度是通过RVS光谱与合适的合成模板光谱的拟合得到的。光谱管道的另一项任务是提供选择这种模板光谱所需的恒星大气参数的一阶估计。我们描述了管道的特征，并提出了详细的校准算法和软件解决方案，我们用来产生在DR2中发表的径向速度。结果。光谱处理管道得到了窄带近红外星等GRVS≤12（即比V ~ 13亮）的盖亚星的中位径向速度。被识别为双线光谱双星的恒星被从管道中移除，而变星、单线和未被检测到的双线光谱双星被视为单星。同样发表在《盖亚DR2》上的对同一颗恒星的不同观测中径向速度的散射，提供了径向速度变化的信息。对于最热（Teff≥7000 K）和最冷（Teff≤3500 K）的恒星，恒星参数估计的准确性和精度不足以选择合适的模板。这些恒星的径向速度是从DR2中去除的。该管道还提供了所获得性能的一阶估计。径向速度测量总体精度约为~200 ~ 300 m s−1，总体精度约为~1 km s−1；最亮的恒星达到~200 m s−1。
Context. The Gaia Data Release 2 (DR2) contains the first release of radial velocities complementing the kinematic data of a sample of about 7 million relatively bright, late-type stars. Aims. This paper provides a detailed description of the Gaia spectroscopic data processing pipeline, and of the approach adopted to derive the radial velocities presented in DR2. Methods. The pipeline must perform four main tasks: (i) clean and reduce the spectra observed with the Radial Velocity Spectrometer (RVS); (ii) calibrate the RVS instrument, including wavelength, straylight, line-spread function, bias non-uniformity, and photometric zeropoint; (iii) extract the radial velocities; and (iv) verify the accuracy and precision of the results. The radial velocity of a star is obtained through a fit of the RVS spectrum relative to an appropriate synthetic template spectrum. An additional task of the spectroscopic pipeline was to provide first-order estimates of the stellar atmospheric parameters required to select such template spectra. We describe the pipeline features and present the detailed calibration algorithms and software solutions we used to produce the radial velocities published in DR2. Results. The spectroscopic processing pipeline produced median radial velocities for Gaia stars with narrow-band near-IR magnitude GRVS ≤ 12 (i.e. brighter than V ~ 13). Stars identified as double-lined spectroscopic binaries were removed from the pipeline, while variable stars, single-lined, and non-detected double-lined spectroscopic binaries were treated as single stars. The scatter in radial velocity among different observations of a same star, also published in Gaia DR2, provides information about radial velocity variability. For the hottest (Teff ≥ 7000 K) and coolest (Teff ≤ 3500 K) stars, the accuracy and precision of the stellar parameter estimates are not sufficient to allow selection of appropriate templates. The radial velocities obtained for these stars were removed from DR2. The pipeline also provides a first-order estimate of the performance obtained. The overall accuracy of radial velocity measurements is around ~200–300 m s−1, and the overall precision is ~1 km s−1; it reaches ~200 m s−1 for the brightest stars.