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GBT Measurements of the Zeeman Effect in the Eridanus/Orion Region. Tim Robishaw Carl Heiles. UC Berkeley. The Orion Molecular Cloud Complex. Heiles 1997. Hat Creek 85 ft 9 years of Zeeman data. Distance ~535 pc Bower, Sandstrom, Goldston. in prep. Starlight Polarization
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GBT Measurements of the Zeeman Effect in the Eridanus/Orion Region Tim Robishaw Carl Heiles UC Berkeley
The Orion Molecular Cloud Complex Heiles 1997 Hat Creek 85 ft 9 years of Zeeman data Distance ~535 pc Bower, Sandstrom, Goldston in prep.
Starlight Polarization Orientations Breger 1976, Vrba et al. 1988
Starlight Polarization Orientations Breger 1976, Vrba et al. 1988
The GBT Is a Zeeman Machine! Off-Axis Design Minimizes Blockage Minimizes Sidelobes!!
Verschuur’s Indictment 1993 BAAS 182 1993 BAAS 183 1995 ApJ 451: 624 1995 ApJ 451: 645
Verschuur’s Indictment 3 hours
Hat Creek 85 foot The GBT 3 hours
Summary • The GBT can be used as a Zeeman detector • Apparent HI self-absorption samples the molecular component of the filament • LOS B field measured in emission changes sign across axis of filament • Detections consistent with previous HI emission measurements: they were reliable! • Field reverses within central half-degree of filament (~ 4.5 pc) • Highest resolution data for modeling of helical magnetic field structure