Oral Presentation

Zeeman effect of the HI narrow self-absorption line, a new systematic probe of magnetic field in molecular cloud

Author(s): Tao-Chung Ching (NRAO)

Presenter: Tao-Chung Ching (NRAO)

Magnetic fields have an important role in the evolution of interstellar medium and star formation. As the only direct probe of interstellar field strength, credible Zeeman measurements remain sparse owing to the lack of suitable Zeeman probes, particularly for cold, molecular gas. Here I report the Zeeman measurements through the HI narrow self-absorption (HINSA) using the FAST and VLA telescopes toward low-mass prestellar cores. The strengths and structures of magnetic fields in the cores revealed by FAST are different from the classical picture where magnetically supercritical cores form out of magnetically subcritical envelopes. The VLA HINSA Zeeman results at high angular resolution show a steep correlation between field strength and gas density. The FAST and VLA results suggest a more efficient mechanism to dissipate magnetic flux than the classical mechanism of ambipolar diffusion. The FAST and VLA results also indicate that HINSA can become a new systematic Zeeman probe.