Polarization Observations of a Sample of Excited OH Masers
- 1University of South Africa
- 2North-West University
Abstract
Spectra of 4.7 and 6.0 GHz excited OH masers from 21 pointings towards known star-forming regions are reported. The C -band observations, using the Green Bank Telescope in full Stokes mode, have measured how polarization properties vary across the maser profiles in each spectrum and vary between different epochs of observation. Seven sources had no detections of masers at any of the OH transitions. Nine sources were observed to have 4.766 GHz masers, which include two new detections in G188.946+0.886 and G196.454–1.677. No new linear or circular polarization was found in any of these masers. Seven and two sources had 6.035 and 6.031 GHz masers, respectively. All 6.035 GHz masers had some level of circular polarization, and three also had linear polarization. Both linear and circular polarization were found in the 6.031 GHz masers in G133.947+1.064 and weak, 100% left circular polarization in G141.918+1.902. Magnetic fields have been calculated from measured Zeeman splittings. The strength and orientation of the fields agree with most previous measurements, although there are some indications that the magnetic fields could be changing. Thermal emission or absorption is seen in several of the 4.7 and 6.0 GHz transitions, many of which have not been reported before.
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BibTeX
@article{smits2026polarization,
title = {{Polarization Observations of a Sample of Excited OH Masers}},
author = {Derck P. Smits and Paul Fallon},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea3ed},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea3ed},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Polarization Observations of a Sample of Excited OH Masers
AU - Derck P. Smits
AU - Paul Fallon
PY - 2026
DA - 2026/10/06
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea3ed
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea3ed
AB - Spectra of 4.7 and 6.0 GHz excited OH masers from 21 pointings towards known star-forming regions are reported. The C -band observations, using the Green Bank Telescope in full Stokes mode, have measured how polarization properties vary across the maser profiles in each spectrum and vary between different epochs of observation. Seven sources had no detections of masers at any of the OH transitions. Nine sources were observed to have 4.766 GHz masers, which include two new detections in G188.946+0.886 and G196.454–1.677. No new linear or circular polarization was found in any of these masers. Seven and two sources had 6.035 and 6.031 GHz masers, respectively. All 6.035 GHz masers had some level of circular polarization, and three also had linear polarization. Both linear and circular polarization were found in the 6.031 GHz masers in G133.947+1.064 and weak, 100% left circular polarization in G141.918+1.902. Magnetic fields have been calculated from measured Zeeman splittings. The strength and orientation of the fields agree with most previous measurements, although there are some indications that the magnetic fields could be changing. Thermal emission or absorption is seen in several of the 4.7 and 6.0 GHz transitions, many of which have not been reported before.
SN - 0004-637X
SN - 1538-4357
ER -