Polarization of seven MBM clouds at high galactic latitude

TL;DR

This study presents polarization measurements of stars near the MBM 33-39 cloud complex, revealing magnetic field alignment with the galactic field, estimating the cloud distance at 120 pc, and suggesting dust grain sizes similar to the Milky Way's interstellar medium.

Contribution

First detailed polarization analysis of MBM 33-39 clouds, determining their distance, magnetic field structure, and dust grain properties, and proposing a formation scenario.

Findings

Magnetic field lines align with the galactic magnetic field.

Cloud distance estimated at 120±10 pc.

Dust grain sizes are comparable to those in the Milky Way.

Abstract

We made R-band polarization measurements of 234 stars towards the direction of MBM 33-39 cloud complex. The distance of MBM 33-39 complex was determined as $120\pm10$ pc using polarization results and near-infrared photometry from the 2MASS survey. The magnetic field geometry of the individual cloud inferred from our polarimetric results reveals that the field lines are in general consistent with the global magnetic field geometry of the region obtained from the previous studies. This implies that the clouds in the complex are permeated by the interstellar magnetic field. Multi-wavelength polarization measurements of a few stars projected on the complex suggest that the size of the dust grains in these clouds is similar to those found in the normal interstellar medium of the Milky Way. We studied a possible formation scenario of MBM 33-39 complex by combining the polarization results from our study and from the literature and by identifying the distribution of ionized, atomic and molecular (dust) components of material in the region.