University of Hertfordshire

From the same journal

From the same journal

By the same authors


View graph of relations
Original languageEnglish
Article number88
Number of pages17
JournalThe Astrophysical Journal
Journal publication date29 May 2019
Publication statusPublished - 29 May 2019


We present the POL-2 850 μm linear polarization map of the Barnard 1 clump in the Perseus molecular cloud complex from the B-fields In STar-forming Region Observations survey at the James Clerk Maxwell Telescope. We find a trend of decreasing polarization fraction as a function of total intensity, which we link to depolarization effects toward higher-density regions of the cloud. We then use the polarization data at 850 μm to infer the plane-of-sky orientation of the large-scale magnetic field in Barnard 1. This magnetic field runs north-south across most of the cloud, with the exception of B1-c, where it turns more east-west. From the dispersion of polarization angles, we calculate a turbulence correlation length of 5.0 ±2.″5 (1500 au) and a turbulent-to-total magnetic energy ratio of 0.5 ±0.3 inside the cloud. We combine this turbulent-to-total magnetic energy ratio with observations of NH 3 molecular lines from the Green Bank Ammonia Survey to estimate the strength of the plane-of-sky component of the magnetic field through the Davis-Chandrasekhar-Fermi method. With a plane-of-sky amplitude of 120 ±60 μG and a criticality criterion λ c = 3.0 ±1.5, we find that Barnard 1 is a supercritical molecular cloud with a magnetic field nearly dominated by its turbulent component.


22 pages, 7 figures, accepted in the Astrophysical Journal

ID: 16669962