New OH Zeeman measurements of magnetic field strengths in molecular clouds
نویسندگان
چکیده
We present the results of a new survey of 23 molecular clouds for the Zeeman effect in OH undertaken with the ATNF Parkes 64-m radio telescope and the NRAO Green Bank 43-m radio telescope. The Zeeman effect was clearly detected in the cloud associated with the H II region RCW 38, with a field strength of 38± 3 μG, and possibly detected in a cloud associated with the H II region RCW 57, with a field strength of −203± 24 μG. The remaining 21 measurements give formal upper limits to the magnetic field strength, with typical 1σ sensitivities < 20 μG. Present Address: Deputy Vice-Chancellor, James Cook University, Townsville, QLD 4811, Australia
منابع مشابه
The Super-alfvénic Model of Molecular Clouds: Predictions for Zeeman Splitting Measurements
We present synthetic OH Zeeman splitting measurements of a super-Alfvénic model of molecular clouds. We select dense cores from synthetic 13CO maps computed from the largest simulation to date of supersonic and super-Alfvénic turbulence. The synthetic Zeeman splitting measurements in the cores yield a relation between the magnetic field strength, B, and the column density, N, in good agreement ...
متن کاملA new probe of magnetic fields during high-mass star formation Zeeman splitting of 6.7 GHz methanol masers
Context. The role of magnetic fields during high-mass star formation is a matter of fierce debate, yet only a few direct probes of magnetic field strengths are available. Aims. The magnetic field is detected in a number of massive star-forming regions through polarization observations of 6.7 GHz methanol masers. Although these masers are the most abundant of the maser species occurring during h...
متن کاملA Model for Oh(1720 Mhz) Masers Associated with Supernova Remnants, and an Application to Sgr a East
OH(1720 MHz) masers unaccompanied by 1665/7 MHz line masers have recently been proposed as indicators of the interaction of supernova remnants (SNRs) and molecular clouds. We present a model for the masing region in which water produced in a C-type shock wave driven into the molecular cloud is dissociated as a result of the X-ray flux from the SNR. We note that the magnetic field strengths infe...
متن کاملExtragalactic Zeeman Detections in Oh Megamasers
We have measured the Zeeman splitting of OH megamaser emission at 1667 MHz from five (ultra)luminous infrared galaxies ([U]LIRGs) using the 305 m Arecibo telescope and the 100 m Green Bank Telescope. Five of eight targeted galaxies show significant Zeeman-splitting detections, with 14 individual masing components detected and line-of-sight magnetic field strengths ranging from ≃ 0.5 − 18 mG. Th...
متن کاملOn the Measurement of the Magnitude and Orientation of the Magnetic Field in Molecular Clouds
We demonstrate that the combination of Zeeman, polarimetry, and ion-to-neutral molecular line width ratio measurements permits the determination of the magnitude and orientation of the magnetic field in the weakly ionized parts of molecular clouds. Zeeman measurements provide the strength of the magnetic field along the line of sight, polarimetry measurements give the field orientation in the p...
متن کامل