First clear detection of the CCS Zeeman splitting toward the pre-stellar core, Taurus Molecular Cloud-1

TL;DR

This study presents the first clear detection of Zeeman splitting in CCS emission toward a prestellar core, revealing a magnetic field strength of about 117 μG and indicating the filament is magnetically supercritical and collapsing.

Contribution

The paper provides the first robust detection of CCS Zeeman splitting in a prestellar core, offering direct measurement of magnetic fields in such environments.

Findings

Magnetic field strength of approximately 117 μG was measured.

The TMC-1 filament is magnetically supercritical.

The filament is collapsing at about 0.6 km/s.

Abstract

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.