TITLE:
Optical Spectroscopic Monitoring Observations of a T Tauri Star V409 Tau
AUTHORS:
Hinako Akimoto, Yoichi Itoh
KEYWORDS:
Star Formation, Pre-Main Sequence Stars, T Tauri Stars
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.9 No.3,
September
19,
2019
ABSTRACT: We report the results of optical spectroscopic monitoring observations of a T Tauri star, V409 Tau. A previous photometric study indicated that this star experienced dimming events due to the obscuration of light from the central star with a distorted circumstellar disk. We conducted medium-resolution (R ~10,000) spectroscopic observations with 2-m Nayuta telescope at Nishi-Harima Astronomical Observatory. Spectra were obtained in 18 nights between November 2015 and March 2016. Several absorption lines such as Ca I and Li, and the Hα emission line were confirmed in the spectra. The Ic-band magnitudes of V409 Tau changed by approximately 1 magnitude during the observation epoch. The equivalent widths of the five absorption lines are roughly constant despite changes in the Ic-band magnitudes. We conclude that the light variation of the star is caused by the obscuration of light from the central star with a distorted circumstellar disk, based on the relationship between the equivalent widths of the absorption lines and the Ic-band magnitudes. The blue component of the Hα emission line was dominant during the observation epoch, and an inverse P Cygni profile was observed in eight of the spectra. The time-variable inverse P Cygni profile of the Hα emission line indicates unsteady mass accretion from the circumstellar disk to the central star.