Author(s)

Kensuke Hosoya​^1*, Yoichi Itoh¹, Yumiko Oasa², Ranjan Gupta³, Asoke Kumar Sen⁴

¹Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, Kobe, Japan.
²Faculty of Education, Saitama University, Saitama, Japan.
³Inter University Center for Astronomy and Astrophysics (IUCAA), Pune, India.
⁴Department of Physics, Assam University, Silchar, India.

The results of a spectroscopic survey of Hα emission line stars associated with fourteen bright rimmed clouds are presented. Slit-less optical spectroscopy was carried out with the Inter University Centre for Astronomy and Astrophysics (IUCAA) 2 m telescope and IUCAA Faint Object Spectrograph and Camera (IFOSC). Hα emission line was detected from 173 objects. Among them 85 objects have a strong Hα emission line with its equivalent width larger than 10 ?. Those are classical T Tauri stars. 52 objects have a weak Hα emission line with its equivalent width less than 10 ? and do not show intrinsic near-infrared excess. Those are weak-line T Tauri stars. On the other hand, 36 objects have a weak Hα emission line (<10 ?), although they show intrinsic near-infrared excess. Such objects are not common in low-mass star forming regions. Those are misfits of the general concept on formation process of a low-mass star, in which it evolves from a classical T Tauri star to a weak-line T Tauri star. Those might be weak-line T Tauri stars with a flared disk in which gas is heated by ultraviolet radiation from a nearby early-type star. Alternatively, we propose pre-transitional disk objects as their evolutional stage.

Star Formation, Pre-Main Sequence Stars, T Tauri Stars

Hosoya​, K. , Itoh, Y. , Oasa, Y. , Gupta, R. and Sen, A. (2019) Spectroscopic Survey of Hα Emission Line Stars Associated with Bright Rimmed Clouds. International Journal of Astronomy and Astrophysics, 9, 154-171. doi: 10.4236/ijaa.2019.92012.