We have developed a sensitive, novel laser heterodyne radiometer using a fiber-coupled distributed feedback laser as the local oscillator to measure Fe(I) Fraunhofer lines Doppler-shifted by the rotational motion of the Sun. The radiometer repetitively measures the Doppler shift of an Fe(I) Fraunhofer line at a vacuum wavelength of 1559.252 nm induced by the Sun’s rotation on its eastern and western limbs. The measured shift is slightly smaller than expected as a result of the simple solar tracking system and collection optics used for demonstration. We show through calculation that a multichannel instrument of identical design in conjunction with a Keck-class telescope can be used to search for exoplanets in nearby star systems using the star-wobble radial velocity method with $1 - \frac{{\rm meter}}{{\rm sec}}$ velocity resolution.

中文翻译：

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被动光学外差光谱法测量由太阳的旋转速度引起的Fe（I）线的多普勒频移

我们已经开发了一种灵敏的新型激光外差辐射计，它使用光纤耦合的分布式反馈激光器作为本机振荡器来测量因太阳旋转运动而发生多普勒频移的Fe（I）Fraunhofer线。辐射计重复测量在1595.252 nm真空波长处的Fe（I）Fraunhofer线的多普勒频移，该真空波长是由太阳在其东西两边的旋转引起的。由于采用了简单的太阳能跟踪系统和用于演示的收集光学系统，因此测得的位移略小于预期值。通过计算表明，可以使用具有相同设计的多通道仪器和Keck级望远镜，使用星摆径向速度方法（$ 1-\ frac {{\ rm meter}}，在附近的恒星系统中搜索系外行星。{{\ rm sec}} $ 速度分辨率。