We present a blind comparison of two methods to measure the mean surface magnetic field strength of the classical T Tauri star CI Tau based on Zeeman broadening of sensitive spectral lines .
Our approach takes advantage of the greater Zeeman broadening at near-infrared compared to optical wavelengths .
We analyze a high signal-to-noise , high spectral resolution spectrum from 1.5–2.5 \mu m observed with IGRINS ( Immersion GRating INfrared Spectrometer ) on the Discovery Channel Telescope .
Both stellar parameterization with MoogStokes ( which assumes an uniform magnetic field ) and modeling with SYNTHMAG ( which includes a distribution of magnetic field strengths ) yield consistent measurements for the mean magnetic field strength of CI Tau is B of \sim 2.2 kG .
This value is typical compared with measurements for other young T Tauri stars and provides an important contribution to the existing sample given it is the only known developed planetary system hosted by a young classical T Tauri star .
Moreover , we potentially identify an interesting and suggestive trend when plotting the effective temperature and the mean magnetic field strength of T Tauri stars .
While a larger sample is needed for confirmation , this trend appears only for a subset of the sample , which may have implications regarding the magnetic field generation .