Near-Infrared Circular Polarization Survey in Star-Forming Regions: Correlations and Trends

TL;DR

This study presents a comprehensive near-infrared circular polarization survey across various star-forming regions, revealing extensive, high-degree CP patterns that decrease with stellar mass, supporting dichroic extinction as the CP origin.

Contribution

It provides the first systematic survey of near-infrared CP in star-forming regions, highlighting the prevalence, extent, and mechanisms of CP in different stellar mass environments.

Findings

CP patterns are generally quadrupolar.

CP regions can extend up to 0.65 pc.

CP degrees reach up to 20% and decrease from high- to low-mass stars.

Abstract

We have conducted a systematic near-infrared circular polarization (CP) survey in star-forming regions, covering high-mass, intermediate-mass, and low-mass young stellar objects. All the observations were made using the SIRPOL imaging polarimeter on the Infrared Survey Facility 1.4 m telescope at the South African Astronomical Observatory. We present the polarization properties of ten sub-regions in six star-forming regions. The polarization patterns, extents, and maximum degrees of linear and circular polarizations are used to determine the prevalence and origin of CP in the star-forming regions. Our results show that the CP pattern is quadrupolar in general, the CP regions are extensive, up to 0.65 pc, the CP degrees are high, up to 20 %, and the CP degrees decrease systematically from high- to low-mass young stellar objects. The results are consistent with dichroic extinction mechanisms generating the high degrees of CP in star forming regions.