The Hot and Dynamic Birth of Massive Stars from the ngVLA Perspective

TL;DR

The paper discusses how the ngVLA telescope will revolutionize our understanding of massive star formation by enabling detailed observations of inner disk regions, dust destruction, and proto-binary dynamics.

Contribution

It highlights the potential of ngVLA to observe dust destruction products, resolve proto-binary motions, and possibly image protostellar surfaces at unprecedented resolutions.

Findings

Detection of gaseous refractories indicating dust destruction.

Demographics of massive multiple systems with separations <10 au.

Potential imaging of protostellar surfaces at 1-mas resolution.

Abstract

The Next Generation Very Large Array (ngVLA) has excellent capabilities to unveil various dynamical and chemical processes in massive star formation at the unexplored innermost regions. Based on the recent observations of ALMA/VLA as well as theoretical predictions, we propose several intriguing topics in massive star formation from the perspective of the ngVLA. In the disk scale of $\lesssim$ 100 au around massive protostars, dust grains are expected to be destructed/sublimated because the physical conditions of temperature, shocks, and radiation are much more intense than those in the envelopes, which are typically observed as hot cores. The high sensitivity and resolution of the ngVLA will enable us to detect the gaseous refractories released by dust destruction, e.g., SiO, NaCl, and AlO, which trace disk kinematics and give new insights into the metallic elements in star-forming regions, i.e., astromineralogy. The multi-epoch survey by the ngVLA will provide demographics of forming massive multiples with separations of $\lesssim$ 10 au with their proper motion. Combining with observations of refractory molecular lines and hydrogen recombination lines, we can reproduce the three-dimensional orbital motions of massive proto-binaries. Moreover, the 1-mas resolution of the ngVLA could possibly take the first-ever picture of the photospheric surface of an accreting protostar, if it is bloated to the au scale by the high accretion rates of mass and thermal energy.