Interaction between the Supernova Remnant HB 3 and the Nearby Star-Forming Region W3

TL;DR

This study reveals the interaction between supernova remnant HB 3 and the W3 star-forming region through millimeter CO observations, showing molecular gas distribution, shock features, and associated young stellar objects, confirming their physical association at 1.95 kpc.

Contribution

First detailed millimeter CO analysis confirming the physical interaction between SNR HB 3 and W3 complex, including molecular gas distribution and star formation correlation.

Findings

Molecular gas around -45 km/s is distributed along the SNR shell.

Shock features indicate interaction between the remnant and molecular cloud.

Young stellar objects are spatially correlated with shocked molecular regions.

Abstract

We performed millimeter observations in CO lines toward the supernova remnant (SNR) HB 3. Substantial molecular gas around -45 km s^-1 is detected in the conjunction region between the SNR HB 3 and the nearby W3 complex. This molecular gas is distributed along the radio continuum shell of the remnant. Furthermore, the shocked molecular gas indicated by line wing broadening features is also distributed along the radio shell and inside it. By both morphological correspondence and dynamical evidence, we confirm that the SNR HB 3 is interacting with the -45 km s^-1 molecular cloud (MC), in essence, with the nearby H II region/MC complex W3. The red-shifted line wing broadening features indicate that the remnant is located at the nearside of the MC. With this association, we could place the remnant at the same distance as the W3/W4 complex, which is 1.95 +- 0.04 kpc. The spatial distribution of aggregated young stellar object candidates (YSOc) shows a correlation to the shocked molecular strip associated with the remnant. We also find a binary clump of CO at (l = 132.94 deg, b = 1.12 deg) around -51.5 km s^-1 inside the projected extent of the remnant, and it is associated with significant mid-infrared (mid-IR) emission. The binary system also has a tail structure resembling the tidal tails of interacting galaxies. According to the analysis of CO emission lines, the larger clump in this binary system is about stable, and the smaller clump is significantly disturbed.