Magnetic Fields and Infall Motions in NGC 1333 IRAS 4

TL;DR

This study uses dust polarimetry and molecular line spectra to investigate magnetic fields and infall motions in NGC 1333 IRAS 4, revealing a uniform magnetic field around IRAS 4A and infall signatures, supporting a critical state of collapse.

Contribution

It provides detailed magnetic field morphology and infall evidence in NGC 1333 IRAS 4, highlighting differences between IRAS 4A and 4B and supporting magnetically supported collapse models.

Findings

Uniform magnetic field around IRAS 4A consistent with collapse models

Infall motions detected via inverse P-Cygni profiles in IRAS 4A

Distinct magnetic field morphology around IRAS 4B

Abstract

We present single-dish 350 micron dust continuum polarimetry as well as HCN and HCO+ J=4-3 rotational emission spectra obtained on NGC 1333 IRAS 4. The polarimetry indicates a uniform field morphology over a 20" radius from the peak continuum flux of IRAS 4A, in agreement with models of magnetically supported cloud collapse. The field morphology around IRAS 4B appears to be quite distinct however, with indications of depolarization observed towards the peak flux of this source. Inverse P-Cygni profiles are observed in the HCN J=4-3 line spectra towards IRAS 4A, providing a clear indication of infall gas motions. Taken together, the evidence gathered here appears to support the scenario that IRAS 4A is a cloud core in a critical state of support against gravitational collapse.