Magnetic Field Structure of the HH 1-2 Region: Near-Infrared Polarimetry of Point-Like Sources

TL;DR

This study used near-infrared polarimetry to map the magnetic field in the HH 1-2 region, revealing a regular magnetic field structure with a strength of about 130 microG, but no influence on protostellar outflow orientations.

Contribution

It provides the first detailed magnetic field map of the HH 1-2 region using near-IR polarimetry, highlighting the field's regularity and its limited role in protostellar outflow directions.

Findings

Magnetic field has a mean polarization angle of 111 degrees.

The magnetic field strength is estimated at about 130 microG.

Outflows show no preferred orientation, indicating weak magnetic influence.

Abstract

The HH 1-2 region in the L1641 molecular cloud was observed in the near-IR J, H, and Ks bands, and imaging polarimetry was performed. Seventy six point-like sources were detected in all three bands. The near-IR polarizations of these sources seem to be caused mostly by the dichroic extinction. Using a color-color diagram, reddened sources with little infrared excess were selected to trace the magnetic field structure of the molecular cloud. The mean polarization position angle of these sources is about 111 deg, which is interpreted as the projected direction of the magnetic field in the observed region of the cloud. The distribution of the polarization angle has a dispersion of about 11 deg, which is smaller than what was measured in previous studies. This small dispersion gives a rough estimate of the strength of the magnetic field to be about 130 microG and suggests that the global magnetic field in this region is quite regular and straight. In contrast, the outflows driven by young stellar objects in this region seem to have no preferred orientation. This discrepancy suggests that the magnetic field in the L1641 molecular cloud does not dictate the orientation of the protostars forming inside.