Magnetic field geometry of the large globule CB 34

TL;DR

This study combines optical and submillimeter polarimetric observations to analyze the magnetic field structure of the Bok globule CB34 across different scales, revealing the magnetic field's orientation and strength relative to star-forming cores and outflows.

Contribution

It provides a multi-scale analysis of magnetic fields in CB34, linking optical and submillimeter data to understand magnetic influence on core structure and outflow alignment.

Findings

Magnetic field constrained to a radius of 10^5 AU around the core.

Core C2's magnetic field is nearly perpendicular to its outflow.

Magnetic field strengths are approximately 34 μG and 70 μG for cores C1 and C2.

Abstract

We report the results of optical polarimetric observations of a Bok globule CB34 to study magnetic field structure on large scales ($10^5-10^6$ AU), which is combined with archival sub-mm observations to characterize the magnetic field structure of CB34 on small scales ($10^4 - 10^5$ AU). The optical polarization measurements indicate that the magnetic field in the globule is constrained to a maximum radius of $10^5$AU around the core, out to densities not smaller than $10^4$cm$^{-3}$. Our study is mainly concentrated on two submillimeter cores C1 and C2 of CB34. The direction of magnetic field of core C2 is found to be nearly perpendicular to the CO outflow direction of the globule. The magnetic field of core C1 is almost aligned with the minor axis of the core which is typical for magnetically dominated star formation models. The mean value of offset between the minor axis of core C2 and the outflow direction is found to be $14^\circ$ which suggests that the direction of the outflow is almost aligned with the minor axis of core C2. The magnetic field strength in the plane-of-sky for cores C1 and C2 is estimated to be $\approx 34\mu$G and $\approx 70\mu$G.