Large-scale magnetic fields in Bok globules
Context. The role of magnetic fields in the star formation process is a contentious matter of debate. In particular, no clear observational proof exists of a general influence by magnetic fields during the initial collapse of molecular clouds.
Aims: Our aim is to examine magnetic fields and their influence on a wide range of spatial scales in low-mass star-forming regions.
Methods: We trace the large-scale magnetic field structure on scales of 103-105 AU in the local environment of Bok globules through optical and near-infrared polarimetry and combine these measurements with existing submillimeter measurements, thereby characterizing the small-scale magnetic field structure on scales of 102-103 AU.
Results: For the first time, we present polarimetric observations in the optical and near-infrared of the three Bok globules B335, CB68, and CB54, combined with archival observations in the submillimeter and the optical. We find a significant polarization signal (P ≳ 2%,P/σP > 3) in the optical and near-infrared for all three globules. Additionally, we detect a connection between the structure on scales of 102-103 AU to 103-104 AU for both B335 and CB68. Furthermore, for CB54, we trace ordered polarization vectors on scales of ~105 AU. We determine a magnetic field orientation that is aligned with the CO outflow in the case of CB54, but nearly perpendicular to the CO outflow for CB68. For B335 we find a change in the magnetic field oriented toward the outflow direction, from the inner core to the outer regions.
Conclusions: We find strongly aligned polarization vectors that indicate dominant magnetic fields on a wide range of spatial scales.
Astronomy and Astrophysics
- Pub Date:
- May 2014
- magnetic fields;
- stars: formation;
- stars: low-mass;
- ISM: clouds;
- instrumentation: polarimeters;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- 9 pages, 7 figures, accepted by A&