Magnetic fields are a critical component of interior and atmospheric models of low-mass stars. Additionally, stellar activity associated with magnetic fields may make exoplanets around K and M stars uninhabitable. Here we describe the measurement of the magnetic fields of K and M dwarfs from high-resolution spectra, and discuss the impact of projected rotational velocity (v sin i) on these measurements. We determine the magnetic fields by measuring the Zeeman effect on Na, Ti, and Ca spectral lines. Observed spectra in our analysis come from the Immersion GRating INfrared Spectrometer (IGRINS), while synthetic spectra were created using the MoogStokes software along with MARCS atmosphere models. We found that measuring Zeeman splitting in R∼45,000 spectra is limited primarily by the projected rotational velocity of the star, but also by spectral resolution, line strength, and spectral signal-to-noise.

磁场是低质量恒星内部和大气模型的重要组成部分。此外，与磁场相关的恒星活动可能会使K和M星周围的系外行星无法居住。在这里，我们从高分辨率光谱描述了K和M矮星磁场的测量，并讨论了投影转速（v  sin  i）对这些测量的影响。我们通过测量在Na，Ti和Ca谱线上的塞曼效应来确定磁场。我们的分析中观察到的光谱来自沉浸式光栅红外光谱仪（IGRINS），而合成光谱则是使用MoogStokes软件和MARCS大气模型创建的。我们发现在R中测量塞曼分裂约45,000个光谱主要受恒星预计的旋转速度限制，但也受光谱分辨率，线强度和光谱信噪比限制。