EVLA Observations of OH Masers in ON 1

TL;DR

This paper presents EVLA observations of 6035 MHz OH masers in ON 1, revealing magnetic field strengths, maser distributions, and polarization characteristics, contributing to understanding the magnetic environment and shock structures in this star-forming region.

Contribution

First EVLA observations of 6035 MHz OH masers in ON 1, providing detailed spatial, magnetic, and polarization data that enhance understanding of maser environments.

Findings

Detected 19 maser features, including six Zeeman pairs.

Magnetic field strength of approximately -10 mG at blueshifted masers.

Distribution suggests shock structures similar to W3(OH).

Abstract

This Letter reports on initial Expanded Very Large Array (EVLA) observations of the 6035 MHz masers in ON 1. The EVLA data are of good quality, lending confidence in the new receiver system. Nineteen maser features, including six Zeeman pairs, are detected. The overall distribution of 6035 MHz OH masers is similar to that of the 1665 MHz OH masers. The spatial resolution is sufficient to unambiguously determine that the magnetic field is strong (~ -10 mG) at the location of the blueshifted masers in the north, consistent with Zeeman splitting detected in 13441 MHz OH masers in the same velocity range. Left and right circularly polarized ground-state features dominate in different regions in the north of the source, which may be due to a combination of magnetic field and velocity gradients. The combined distribution of all OH masers toward the south is suggestive of a shock structure of the sort previously seen in W3(OH).