We present a multi-epoch spectroscopic study of LkCa 4, a heavily spotted
non-accreting T Tauri star. Using SpeX at NASA's Infrared Telescope Facility
(IRTF), 12 spectra were collected over five consecutive nights, spanning
≈ 1.5 stellar rotations. Using the IRTF SpeX Spectral Library, we
constructed empirical composite models of spotted stars by combining a warmer
(photosphere) standard star spectrum with a cooler (spot) standard weighted by
the spot filling factor, fspot. The best-fit models spanned two
photospheric component temperatures, Tphot = 4100 K (K7V) and 4400 K
(K5V), and one spot component temperature, Tspot = 3060 K (M5V) with an
AV of 0.3. We find values of fspot to vary between 0.77 and 0.94 with
an average uncertainty of ∼0.04. The variability of fspot is periodic
and correlates with its 3.374 day rotational period. Using a mean value for
fspotmean to represent the total spot coverage, we calculated spot
corrected values for Teff and L⋆. Placing these values alongside
evolutionary models developed for heavily spotted young stars, we infer mass
and age ranges of 0.45-0.6 M⊙ and 0.50-1.25 Myr, respectively. These
inferred values represent a twofold increase in the mass and a twofold decrease
in the age as compared to standard evolutionary models. Such a result
highlights the need for constraining the contributions of cool and warm regions
of young stellar atmospheres when estimating Teff and L⋆ to infer
masses and ages as well as the necessity for models to account for the effects
of these regions on the early evolution of low-mass stars.Comment: 21 pages, 9 Figures; Accepted for publication in Ap