Document Type

Article

Publication Date

3-1-2023

Publication Title

Astrophysical Journal

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 meanspot 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.

Volume

946

Issue

1

DOI

10.3847/1538-4357/acbb61

ISSN

0004637X

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Rights

© 2023. The Author(s)

Comments

Archived as published.

Download

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.