  A new generation of dedicated Doppler spectrographs will attempt to detect
low-mass exoplanets around mid-late M stars at near infrared (NIR) wavelengths,
where those stars are brightest and have the most Doppler information content.
A central requirement for the success of these instruments is to properly
measure the component of radial velocity (RV) variability contributed by
stellar magnetic activity and to account for it in exoplanet models of RV data.
The wavelength coverage for many of these new instruments will not include the
Ca II H&K or H-alpha lines, the most frequently used absorption-line tracers of
magnetic activity. Thus, it is necessary to define and characterize NIR
activity indicators for mid-late M stars in order to provide simultaneous
activity metrics for NIR RV data. We have used the high-cadence UVES
observations of the M5.5 dwarf Proxima Centauri from Fuhrmeister et al. (2011)
to compare the activity sensitivity of 8 NIR atomic lines to that of H-alpha.
We find that equivalent width-type measurements of the NIR K I doublet and the
Ca II NIR triplet are excellent proxies for the canonical optical tracers. The
Ca II triplet will be acquired by most of the new and upcoming NIR Doppler
spectrographs, offering a common, reliable indicator of activity.
