An Expanding HI Photodissociated Region Associated with the Compact HII Region G213.880-11.837 in the GGD 14 Complex

TL;DR

This study uses high-resolution HI 21cm line observations to analyze the expanding photodissociated region of a compact HII region, revealing a champagne flow and expanding neutral gas in the GGD 14 complex.

Contribution

It provides detailed kinematic and morphological analysis of the HI region associated with G213.880-11.837, demonstrating an expanding flow and champagne flow in a rare cometary HII/HI region.

Findings

Neutral gas is part of an expanding flow.

HI emission extends toward the SE with velocities up to 14 km/s.

The region exhibits a champagne flow with an ambient velocity of 11.5 km/s.

Abstract

We present high angular and spectral resolution HI 21~cm line observations toward the cometary-shaped compact HII region G213.880-11.837 in the GGD~14 complex.The kinematics and morphology of the photodissociated region, traced by the HI line emission, reveal that the neutral gas is part of an expanding flow. The kinematics of the HI gas along the major axis of G213.880-11.837 shows that the emission is very extended toward the SE direction, reaching LSR radial velocities in the tail of about 14 km/s. The ambient LSR radial velocity of the molecular gas is 11.5 km/s, which suggests a champagne flow of the HI gas. This is the second (after G111.61+0.37) cometary HII/HI region known.