Broad-band Optical Polarimetric Studies toward the Galactic young star cluster Be 59

TL;DR

This study uses optical polarimetry to analyze dust layers and magnetic fields in the young star cluster Be 59, revealing multiple dust layers, an anomalous reddening law, and variations in polarization with distance.

Contribution

It provides detailed multiwavelength polarimetric data and insights into dust properties and magnetic field structure in Be 59, improving cluster member identification and understanding of dust grain characteristics.

Findings

Three dust layers at ~300, ~500, and ~700 pc identified.

Anomalous reddening law indicating larger dust grains.

Polarization and E(B - V) increase with distance from cluster center.

Abstract

We present multiwavelength optical linear polarimetric observations of 69 stars toward the young open cluster Be 59. The observations reveal the presence of three dust layers located at the distances of \sim300, \sim500 and \sim700 pc. The dust layers produce a total polarization Pv \sim 5.5 per cent. The mean values of polarization and polarization angles due to the dust layers are found to increase systematically with distance. We show that polarimetry in combination with the (U - B) - (B - V) colour-colour diagram yields a better identification of cluster members. The polarization measurements suggest that the polarization due the intra-cluster medium is \sim 2.2 per cent. An anomalous reddening law exists for the cluster region, indicating a relatively larger grain size than that in the diffuse ISM. The spatial variation of the polarization and E(B - V) is found to increase with radial distance from the cluster center, whereas the {\theta}v and {\lambda}max are found to decrease with increasing radial distance from the cluster center. About 40 per cent of cluster members show the signatures of either intrinsic polarization or rotation in their polarization angles. There is an indication that the star light of the cluster members might have been depolarized because of non-uniform alignment of dust grains in the foreground dust layers and in the intra-cluster medium.