Near-Infrared Imaging Polarimetry of the NGC 2071 Star-Forming Region with SIRPOL

Abstract

Abstract We conducted deep JHK$_{\rm s}$ imaging polarimetry of a $\sim$ 8$' \times$ 8$'$ area of the NGC 2071 star-forming region. Our polarization data revealed various infrared reflection nebulae (IRNe) associated with the central IR young star cluster NGC 2071IR and identified their illuminating sources. There are at least 4 IRNe in NGC 2071IR, and several additional IRNe were identified around nearby young stars in the same field-of-view. Each illuminating source coincides with a known near-IR source, except for IRS 3, which is only a part of IRN 2 and is illuminated by the radio source 1c. Aperture polarimetry of each cluster source was used to detect unresolved circumstellar disk/outflow systems. Aperture polarimetry of the other point-like sources within the field was conducted in this region for the first time. The magnetic field structures (from $\sim$ 1 pc down to $\sim$ 0.1 pc) were derived using both aperture polarimetry of the point-like sources and imaging polarimetry of the shocked H$_2$ emission that is seen as the dominant knotty nebulae in the $K_{\rm s}$ band image; both are of dichroic origin and the derived field directions are consistent with each other. The magnetic field direction projected on the sky is also consistent with that inferred from the 850$\mu$m thermal continuum emission polarimetry of the central 0.2 pc region, but is running roughly perpendicular ($\sim$ 75$^{\circ}$) to the direction of the large-scale outflow. We argue that the field strength is too weak to align the outflow in the large-scale field direction via magnetic braking.