# Zooming in to Massive Star Birth

## TL;DR

This study uses high-resolution ALMA observations to identify and analyze a massive, starless core in a dark cloud, providing insights into its physical state and potential for star formation.

## Contribution

It reports the first detailed imaging of a massive starless core, revealing its properties and dynamical state, and discusses magnetic field implications.

## Key findings

- C1-S is a massive, compact, starless core with no outflow activity.
- The core is likely on the verge of collapse, with sub-virial velocity dispersion.
- Magnetic fields of around 2 mG could stabilize the core in virial equilibrium.

## Abstract

We present high resolution (0.2", 1000 AU) 1.3 mm ALMA observations of massive infrared dark cloud clump, G028.37+00.07-C1, thought to harbor the early stages of massive star formation. Using $\rm N_2D^+$(3-2) we resolve the previously identified C1-S core, separating the bulk of its emission from two nearby protostellar sources. C1-S is thus identified as a massive ($\sim50\:M_\odot$), compact ($\sim0.1\:$pc diameter) starless core, e.g., with no signs of outflow activity. Being highly deuterated, this is a promising candidate for a pre-stellar core on the verge of collapse. An analysis of its dynamical state indicates a sub-virial velocity dispersion compared to a trans-Alfv\'enic turbulent core model. However, virial equilibrium could be achieved with sub-Alfv\'enic conditions involving $\sim2\:$mG magnetic field strengths.