Oral Presentation

Revealing the Evolution Timescale of Protoplanetary Disks with High-resolution Spectroscopy

Author(s): Yuhei Takagi (Subaru Telescope), Yoichi Itoh (University of Hyogo), Yumiko Oasa (Saitama University)

Presenter: Yuhei Takagi (Subaru Telescope)

We present the results of investigations of evolution timescale of protoplanetary disks in nearby star-forming regions. This study is based on an age determination method of pre-main sequence stars with high-resolution optical and near-infrared spectroscopy. We determined the ages of pre-main sequence stars with 0.5 - 1.5 solar mass, observed with Subaru Telescope / HDS and IRCS. We used equivalent width ratios of nearby absorption lines as surface gravity indicators. Since the filling-in effect due to the continuum excess is nearly uniform over a limited wavelength range, the equivalent width ratio directly reflects the parameters of the stellar atmosphere. Ages of the pre-main sequence stars were estimated by comparing the derived surface gravities to the evolutionary models. From a comparison of determined ages and near-infrared color excesses arising from the disk, the inner disk lifetime of young stars in Taurus and Ophiuchus are estimated to be 2.4 Myr and 1.2 Myr (Takagi et al. 2014, 2015), respectively. This result indicates that the disk evolution timescale depends on the environment of the star-forming region.