Abstract
Abstract
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, f
spot. The best-fit models spanned two photospheric component temperatures, T
phot = 4100 K (K7V) and 4400 K (K5V), and one spot component temperature, T
spot = 3060 K (M5V) with an A
V
of 0.3. We find values of f
spot to vary between 0.77 and 0.94 with an average uncertainty of ∼0.04. The variability of f
spot is periodic and correlates with its 3.374 day rotational period. Using a mean value for f
mean
spot to represent the total spot coverage, we calculated spot corrected values for T
eff 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 T
eff 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.
Funder
National Science Foundation
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
1 articles.
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