We report a first clear detection of the Zeeman splitting of a CCS emission line at 45 GHz toward a nearby prestellar dense filament, Taurus Molecular Cloud-1. We observed HC3N non-Zeeman line simultaneously as the CCS line, and did not detect any significant splitting of HC3N line. Thus, we conclude that our detection of the CCS Zeeman splitting is robust. The derived \textcolor{black}{line-of-sight} magnetic field strength is about 117 ± 21 μG, which corresponds to the normalized mass-to-magnetic flux ratio of 2.2 if we adopt the inclination angle of 45∘. Thus, we conclude that the TMC-1 filament is magnetically supercritical. Recent radiative transfer calculations of CCS and HC3N lines along the line of sight suggest that the filament is collapsing with a speed of ∼ 0.6 km s−1, which is comparable to three times the isothermal sound speed. This infall velocity appears to be consistent with the evolution of a gravitationally-infalling core.
@article{arxiv.1908.07708,
title = {First clear detection of the CCS Zeeman splitting toward the pre-stellar core, Taurus Molecular Cloud-1},
author = {Fumitaka Nakamura and Seiji Kameno and Takayoshi Kusune and Izumi Mizuno and Kazuhito Dobashi and Tomomi Shimoikura and Kotomi Taniguchi},
journal= {arXiv preprint arXiv:1908.07708},
year = {2020}
}