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تسجيل مستخدم جديدFirst clear detection of the CCS Zeeman splitting toward the pre-stellar core, Taurus Molecular Cloud-1
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Fumitaka Nakamura
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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 HC$_3$N non-Zeeman line simultaneously as the CCS line, and did not detect any significant splitting of HC$_3$N 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 $pm$ 21 $mu$G, which corresponds to the normalized mass-to-magnetic flux ratio of 2.2 if we adopt the inclination angle of 45$^circ$. Thus, we conclude that the TMC-1 filament is magnetically supercritical. Recent radiative transfer calculations of CCS and HC$_3$N lines along the line of sight suggest that the filament is collapsing with a speed of $sim$ 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.
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