Spectroscopic Survey of H{\alpha} Emission Line Stars Associated with Bright Rimmed Clouds

TL;DR

This spectroscopic survey identified and classified H alpha emission line stars in bright rimmed clouds, revealing diverse T Tauri star types and suggesting complex star formation and disk evolution processes influenced by nearby stars.

Contribution

First comprehensive spectroscopic survey of H alpha emission stars in bright rimmed clouds, providing insights into star formation stages and disk evolution.

Findings

173 H alpha emission stars detected

Presence of classical and weak-line T Tauri stars

Identification of potential pre-transitional disk objects

Abstract

The results of a spectroscopic survey of H alpha 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) 2m telescope and IUCAA Faint Object Spectrograph and Camera (IFOSC). H alpha emission line was detected from 173 objects. Among them 85 objects have a strong H alpha emission line with its equivalent width larger than 10 A. Those are classical T Tauri stars. 52 objects have a weak H alpha emission line with its equivalent width less than 10 A and do not show intrinsic near-infrared excess. Those are weak-line T Tauri stars. On the other hand, 36 objects have a weak H alpha emission line (<10 A), 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.