N131: A dust bubble born from the disruption of a gas filament

TL;DR

This study investigates the formation and fragmentation of the infrared dust bubble N131, revealing its origin from a disrupted gas filament influenced by stellar winds and HII region expansion, supported by multi-wavelength observations.

Contribution

It presents a detailed multi-wavelength analysis of N131, proposing a new formation scenario involving filament disruption, stellar winds, and self-gravity, which advances understanding of bubble formation mechanisms.

Findings

N131 features a ringlike shell with compact fragments and filamentary structures.

A secondary bubble N131-A is detected with an ionizing flux from an O9.5 star.

The bubble's formation is linked to gas filament disruption by stellar feedback.

Abstract

OB type stars have strong ionizing radiation, and drive energetic winds. The ultraviolet (UV) radiation from ionizing stars may heat dust and ionize gas to sweep up an expanding bubble shell. This shell may be the result of feedback leading to a new generation of stars. N131 is an infrared dust bubble residing in a molecular filament. We study the formation and fragmentation of this bubble with multi-wavelength dust and gas observations. Towards the bubble N131, we analyzed archival multi-wavelength observations including 3.6, 4.5, 5.8, 8.0, 24, 70, 160, 250, 350, 500 $\mu$m, 1.1 mm, and 21 cm. In addition, we performed new observations of CO (2-1), CO (1-0), and $^{13}$CO (1-0) with the IRAM 30-m telescope. Multi-wavelength dust and gas observations reveal a ringlike shell with compact fragments, two filamentary structures, and a secondary bubble N131-A. The bubble N131 is a rare object with a large hole at 24 $\mu$m and 21 cm in the direction of its center. The dust and gas clumps are compact and might have been compressed at the inner edge of the ringlike shell, while they are extended and might be pre-existing at the outer edge. The column density, excitation temperature, and velocity show a potentially hierarchical distribution from the inner to outer edge of the ringlike shell. We also detected the front and back sides of the secondary bubble N131-A in the direction of its center. The derived Lyman-continuum ionizing photon flux within N131-A is equivalent to an O9.5 star. Based on the above, we suggest that the bubble N131 might be triggered by the strong stellar winds from a group of massive stars inside the bubble. We propose a scenario in which the bubble N131 forms from the disruption of a gas filament by expansion of HII region, strong stellar winds, and fragments under self-gravity.