Maser maps and magnetic field of OH 300.969+1.147

TL;DR

This study maps the magnetic field and maser distribution in the OH 300.969+1.147 region, revealing detailed magnetic field estimates and maser spot characteristics using high-resolution radio observations.

Contribution

It provides high-resolution maps of maser spots and magnetic fields in OH 300.969+1.147, including Zeeman pair analysis, offering new insights into magnetic environments in evolved star-forming regions.

Findings

59 maser spots mapped over 2 arcseconds

Magnetic field estimates range from -1.1 to -4.7 mG

Consistent magnetic field direction across the site

Abstract

The southern maser site OH 300.969+1.147 has been studied using the Long Baseline Array of the Australia Telescope National Facility. The 1665- and 1667-MHz hydroxyl ground-state transitions were observed simultaneously. A series of maps with tenth-arcsec spatial resolution, at velocity spacing 0.09 km/s, and in both senses of circular polarization, reveal 59 small diameter maser spots. The spots are scattered over 2-arcsec, coincident with a strong ultracompact HII region, at a distance of 4.3 kpc. 17 Zeeman pairs of oppositely polarized spots were found, all yielding magnetic field estimates towards us (negative), ranging from -1.1 to -4.7 mG, with a median value of -3.5 mG. Excited state masers of OH at 6035 MHz and 6030 MHz at this site also display Zeeman pairs revealing a magnetic field of -5.0 mG. Weak methanol maser emission is intermingled with the OH masers, but there is no detectable closely related water maser. The consistent magnetic field direction found within this site is a striking feature of several other maser sites associated with strong HII regions studied in comparable detail. We interpret the site as a mature region nearing the end of the brief evolutionary stage that can support maser emission.