Abstract
We discuss the significance of previously published OH Zeeman effect measurements of the magnetic field in the p Oph cloud (L1688) and also a new OH Zeeman effect measurement for the dark cloud core TMC-1C, the latter obtained with the Arecibo telescope. Results for both of these clouds, like previously published OH Zeeman results for other dark clouds, show that the line-of-sight field strength |B∥|≤ 10 μG. The p Oph cloud is significantly higher in column density than other clouds studied, and recent H I Zeeman effect observations have revealed B∥ ≈ +10 μG in the H I self-absorption region in front of the cloud. The low values of B∥ derived from the OH Zeeman effect may indicate that OH poorly samples the dense gas in the ρ Oph cloud, or else that the cloud is in a state of supercritical collapse. The TMC-1C cloud core may have formed via ambipolar diffusion in a manner similar to recent modeling of dark cloud Barnard 1.
Original language | English |
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Pages (from-to) | 302-307 |
Number of pages | 6 |
Journal | Astrophysical Journal |
Volume | 471 |
Issue number | 1 PART I |
DOIs | |
State | Published - 1996 |
Keywords
- ISM: Clouds
- ISM: Individual (rho ophiuchi, taurus)
- ISM: Magnetic fields ISM: Molecules
- Polarization
- Stars: Formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science