Magnetic field measurement in TMC-1C using 22.3 GHz CCS Zeeman splitting

TL;DR

This study uses radio interferometry to detect Zeeman splitting in CCS emission from TMC-1C, providing magnetic field measurements that inform star formation theories in dense molecular clouds.

Contribution

First detection of CCS Zeeman splitting in TMC-1C, demonstrating the potential of deep CCS observations for magnetic field measurements in star-forming regions.

Findings

Magnetic field of ~2 mG detected in TMC-1C envelope.

Magnetic field strength consistent with subcritical envelope and supercritical core.

Ambipolar diffusion timescale aligns with chemical modeling predictions.

Abstract

Measurement of magnetic fields in dense molecular clouds is essential for understanding the fragmentation process prior to star formation. Radio interferometric observations of CCS 22.3 GHz emission, from the starless core TMC-1C, have been carried out with the Karl G. Jansky Very Large Array to search for Zeeman splitting of the line in order to constrain the magnetic field strength. Toward a region offset from the dust peak, we report a detection of the Zeeman splitting of the CCS 2_1 - 1_0 transition, with an inferred magnetic field of ~2 mG. If we interpret the dust peak to be the core of TMC-1C, and the region where we have made a detection of the magnetic field to be the envelope, then our observed value for the magnetic field is consistent with a subcritical mass-to-flux ratio envelope around a core with supercritical mass-to-flux ratio. The ambipolar diffusion timescale for the formation of the core is consistent with the relevant timescale based on chemical modeling of the TMC-1C core. This work demonstrates the potential of deep CCS observation to carry out future measurements of magnetic field strengths in dense molecular clouds and, in turn, understand the role of the magnetic field in star formation.