Kinematics of the Galactic Bubble RCW 120

TL;DR

This study investigates the kinematics and density structure of the Galactic bubble RCW 120 through spectroscopic observations and 3D simulations, revealing localized expansion, density gradients, and matching ambient density estimates.

Contribution

It provides the first detailed kinematic analysis of RCW 120 combined with 3D numerical modeling to understand its shell dynamics and morphology.

Findings

Expansion detected only in the northeast region (20-30 km/s)

Electron density around 4000 cm^{-3} in the southwest region

Numerical models predict ambient density between 3000-5000 cm^{-3}

Abstract

We studied the kinematics of the Galactic bubble RCW 120 in the [SII]\lambda\lambda$6717,6731\AA lines. We measured a LSR radial velocity ranging from ~-74 to ~-6km/s. We found evidence of expansion only in the northeast region of the nebula (from 20 to 30 km/s). We found a high electron density around 4000 cm^{-3} in the south-west region and we also found two arches-like structure indicating a density gradient. We present 3D numerical simulations of RCW 120 using Walicxe-3D code in order to explore optical shell dynamics and its morphology. Our numerical results predict an average numerical electron density of the ambient medium (in the southern region of the object) is between 3000 to 5000 cm^{-3} in agreement with our values obtained from the observations. From our models, we do not expect X-ray emission coming from the external shell, due to the low expansion velocity value.}