The magnetic field of the L1544 starless dark cloud, traced using near-infrared background starlight (Presentation)
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Citation (published version)D Clemens, Paul Goldsmith, Kostas Tassis. 2017. "The Magnetic Field of the L1544 Starless Dark Cloud, Traced Using Near-Infrared Background Starlight."
What roles do interstellar magnetic fields play in star formation processes? We have studied the B-field of L1544, a dark cloud with a starless dense core showing active gas infall, and located only 140 pc away in Taurus, via deep near-infrared (NIR) imaging polarimetry with the Mimir instrument. We find the B-field orientations in the plane of the sky change significantly at L1544, mimicking its shape and extent. The elongated spine of L1544 is also where the dispersion of NIR linear polarization position angles is smallest, suggesting strengthening of the B-field. Archival WISE, SCUPOL, Herschel, and Planck data were analyzed to characterize dust extinction and emission across L1544 and the field around it. Three-dimensional modeling, constrained through matching two-dimensional integrated model properties to observed dust distributions, led us to develop maps of effective gas mass densities and non-thermal gas velocity dispersions. These were combined with the NIR polarimetry, under the Chandrasekhar & Fermi (1953) approach, to yield a map of B-field strength across the entire 400 sq-arcmin region surveyed. The trends of B-field strength with gas volume density, mass-to-flux ratio with radius, and plane-of-sky B-field strengths with Zeeman-traced line-of-sight B-field strengths were found and compared to previous published work to establish the role of B-fields in L1544. We find field strengths in the 3 - 30 uG range, quite similar to the OH Zeeman values found by Crutcher et al. (2009) for L1544.This work was partially supported by grants to Boston University from NSF (AST-0907790, 1412269) and NASA (NNX15AE51G).