New ex-OH maser detections in the northern celestial hemisphere

TL;DR

This study reports the detection of three excited hydroxyl maser lines in northern star-forming regions, confirming some previous detections, suggesting variability, and estimating magnetic field strengths using high-resolution radio observations.

Contribution

It provides new ex-OH maser detections in the northern hemisphere and estimates magnetic fields, filling a geographic gap in maser surveys and advancing understanding of star-forming regions.

Findings

Detected three ex-OH maser lines at 6035 MHz in northern regions.

Confirmed recent detections of two ex-OH masers and suggested variability in one.

Estimated magnetic field strengths in masering regions using polarization data.

Abstract

Aims.Molecular masers, including methanol and hydroxyl masers, and in particular the ones in excited rotational states (ex-OHmasers), are one of the most informative tools for studying star-forming regions. So, the discovery, of new maser sources in theseregions is of great importance. Many studies and surveys of ex-OH maser sources have been carried out in the southern celestialhemisphere, but only a few have been done in the northern hemisphere. The specific aim of this work is to close this gap.Methods.The star-forming regions in the northern hemisphere with known active methanol masers were observed to search for newex-OH maser sources with the 32 m and 16 m radio telescopes of the Ventspils International Radio Astronomy Centre (VIRAC).Results.Three OH maser lines in the excited state at the 6035 MHz in three northern hemisphere star-forming regions are detected.The maser 189.030+0.783 was previously known, but we suggest this maser is a possible variable. We confirm recent detections ofthe ex-OH masers 85.41+0.00 and 90.92+1.49 by other authors. The magnetic field strength in the masering regions is estimated byusing right circular polarization (RCP) and left circular polarization (LCP) pair splitting. The high-velocity resolution provides uswith an estimation of a comparatively small magnetic field strength for the 189.030+0.783 and 90.92+1.49 star-forming regions