Kinematic Study of Molecular Gas in Cometary Globule -- LBN 437

TL;DR

This paper investigates the gas movements in the cometary globule LBN 437, revealing signs of infall and early star formation stages through molecular line observations, contributing to understanding star formation in UV-irradiated environments.

Contribution

It provides the first detailed kinematic analysis of LBN 437 using CO molecular lines, highlighting infall motions and early star formation indicators.

Findings

Detection of infalling gas in the globule's head

Mean infall velocity of 0.25 km/s

Mass infall rate of 0.508 Msun/yr

Abstract

Bright-rimmed, cometary-shaped star-forming globules, associated with HII regions, are remnants of compressed molecular shells exposed to ultraviolet radiation from central OB-type stars. The interplay between dense molecular gas and ionizing radiation, analysed through gas kinematics, provides significant insights into the nature and dynamic evolution of these globules. This study presents the results of a kinematic analysis of the cometary globule, Lynds Bright Nebula (LBN) 437, focusing on the first rotational transition of 12CO and C18O molecular lines observed using the Taeduk Radio Astronomy Observatory (TRAO). The averaged 12CO spectrum shows a slightly skewed profile, suggesting the possibility of a contracting cloud. The molecular gas kinematics reveals signatures of infalling gas in the cometary head of LBN 437, indicating the initial stages of star formation. The mean infall velocity and mass infall rate towards the cometary head of LBN 437 are 0.25 km s^-1 and 5.08 * 10^-1 Msun yr^-1 respectively, which align well with the previous studies on intermediate or high-mass star formation.