Star-Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Zhen Guo, Gregory J. Herczeg, Jessy Jose, Jianning Fu, Po Shih Chiang, Konstantin Grankin, Raul Michel, Ram Kesh Yadav, Jinzhong Liu, Wen Ping Chen, Gang Li, Huifang Xue, Hubiao Niu, Annapurni Subramaniam, Saurabh Sharma, Nikom Prasert, Nahiely Flores-Fajardo, Angel Castro, Liliana Altamirano

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15 Scopus citations

Abstract

The variability of young stellar objects is mostly driven by star-disk interactions. In long-term photometricmonitoring of the accreting T Tauri star GI Tau, we detect extinction events with typical depths of DV ~ 2.5 magthat last for days to months and often appear to occur stochastically. In 2014-2015, extinctions that repeated with aquasi-period of 21 days over several months are the first empirical evidence of slow warps predicted bymagnetohydrodynamic simulations to form at a few stellar radii away from the central star. The reddening isconsistent with RV = 3.85 ± 0.5 and, along with an absence of diffuse interstellar bands, indicates that some dustprocessing 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 isinitially dominated by a month-long extinction event and a return to the unocculted brightness. The subsequentlight curve then features spot modulation with a 7.03 day period, punctuated by brief, randomly spaced extinctionevents. The accretion rate measured from U-band photometry ranges from 1.3×10-8 to 1.1×10-10 Me yr-1(excluding the highest and lowest 5% of high- and low- accretion rate outliers), with an average of 4.7×10-9 Me yr-1. A total of 50% of the mass is accreted during bursts of >12.8×10-9 Me yr-1, which indicateslimitations on analyses of disk evolution using single-epoch accretion rates.

Original languageEnglish
Article number56
JournalAstrophysical Journal
Volume852
Issue number1
DOIs
StatePublished - 1 Jan 2018

Keywords

  • Herbig Ae/Be
  • stars: pre-main sequence
  • stars: variables: T Tauri

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