Astrophys. J., 852, 56-56 (2018/January-1)
Star-disk interactions in multiband photometric monitoring of the classical T Tauri star GI Tau.
GUO Z., HERCZEG G.J., JOSE J., FU J., CHIANG P.-S., GRANKIN K., MICHEL R., YADAV R.K., LIU J., CHEN W.-P., LI G., XUE H., NIU H., SUBRAMANIAM A., SHARMA S., PRASERT N., FLORES-FAJARDO N., CASTRO A. and ALTAMIRANO L.
Abstract (from CDS):
The variability of young stellar objects is mostly driven by star-disk interactions. In long-term photometric monitoring of the accreting T Tauri star GI Tau, we detect extinction events with typical depths of ΔV∼2.5 mag that last for days to months and often appear to occur stochastically. In 2014-2015, extinctions that repeated with a quasi-period of 21 days over several months are the first empirical evidence of slow warps predicted by magnetohydrodynamic simulations to form at a few stellar radii away from the central star. The reddening is consistent with RV=3.85±0.5 and, along with an absence of diffuse interstellar bands, indicates that some dust processing has occurred in the disk. The 2015-2016 multiband light curve includes variations in spot coverage, extinction, and accretion, each of which results in different traces in color-magnitude diagrams. This light curve is initially dominated by a month-long extinction event and a return to the unocculted brightness. The subsequent light curve then features spot modulation with a 7.03 day period, punctuated by brief, randomly spaced extinction events. The accretion rate measured from U-band photometry ranges from 1.3×10–8 to 1.1×10–10M☉ yr–1 (excluding the highest and lowest 5% of high- and low- accretion rate outliers), with an average of 4.7 ×10–9M☉ yr–1. A total of 50% of the mass is accreted during bursts of 12.8×10–9M☉ yr–1, which indicates limitations on analyses of disk evolution using single-epoch accretion rates.
© 2018. The American Astronomical Society.
stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be - stars: variables: T Tauri, Herbig Ae/Be
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