New Zeeman Effect Measurements of Thermal OH Sources S106, Orion B, B1, and L134 at 1665 and 1667 MHz

Abstract

view Abstract Citations (4) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS New Zeeman Effect Measurements of Thermal OH Sources S106, Orion B, B1, and L134 at 1665 and 1667 MHz Verschuur, Gerrit L. Abstract Zeeman effect observations of four thermal OH sources, S106, Bl, Orion B (NGC 2024), and L134, were carried out at 1665 and 1667 MHz with the 140 ft radio telescope of the NRAO. The goal was to determine whether previous observations of the same sources by other workers using the same telescope were possibly influenced by systematic effects similar to those which have beset observations of the Zeeman effect in interstellar H I emission profiles. The 18 cm feed used here has polarized beam structure nearly 100 times lower than was apparently the case for the feed used by the other workers. Analysis of the new observations indicates that the presence of nonthermal components in the putative thermal profiles appears capable of confusing the results. Unless the existence of such components is ruled out, interpretation of the single-dish radio telescope Zeeman effect may be ambiguous, even if the observations are performed with a feed with very low polarized beam structure. Publication: The Astronomical Journal Pub Date: December 1996 DOI: 10.1086/118216 Bibcode: 1996AJ....112.2718V Keywords: ISM: MAGNETIC FIELDS; ISM: KINEMATICS AND DYNAMICS; RADIO LINES: ISM full text sources ADS | data products SIMBAD (6)