Laying the Groundwork for Future Alma Direct Magnetic Field Detection in Protostellar Environments

COX, ERIN G.; HARRIS, ROBERT J; L.W. LOONEY; SEGURA-COX, D.; CRUTCHER, RICHARD; LI, ZHI-YUN; TOBIN, JOHN; STEPHENS, I.W.; MANUEL FERNANDEZ LOPEZ

Simposio; 72nd International Symposium on Molecular Spectroscopy; 2017

Magnetic fields are a crucial element of the star formation process on many scales, from controlling jet and outflow formation on large scales, determining the structure of any protostellar disk, to modulating the accretion rate onto the central protostar. Both the three-dimensional structure and the field strength are important in determining the outcome of star formation. Unfortunately, the method most commonly used to infer magnetic field structure - linearly polarized dust continuum emission - is limited to the plane-of-sky field structure, and gives no reliable information on field strength. Alternatively, observations of the Zeeman effect in transitions of paramagnetic molecules, especially CN, are one of the best prospects for making such measurements due to the molecules´ high Zeeman coefficients. In particular, these observations have been used in determining field strengths on cloud-size scales. However, CN and other paramagnetic molecules have, to our knowledge, never been observed in the envelopes/disks of Class 0 protostars at ̃arcsecond resolution, due both to sensitivity and resolution limits of previous generations of millimeter-wave interferometers. Because field strengths near the protostar are so important to understand the star formation process, we have conducted a snapshot ALMA Band 3 (3 mm / 113 GHz) survey of the 10 brightest Class 0 protostars in the Perseus, Taurus, and ρ Ophiuchus molecular clouds in the regions surrounding five transitions of four paramagnetic species, including CN, SO, C_2S, and C_4H. We present this survey - the principle goal of which was to assess the brightness of the lines within ̃ 1000 AU of the protostar - and assess the likelihood of using ALMA observations of the Zeeman effect to determine protostellar magnetic field strength.