Weak and Compact Radio Emission in Early Massive Star Formation Regions: An Ionized Jet Toward G11.11-0.12P1

TL;DR

This study presents radio and infrared observations of a massive protostar, revealing a thermal ionized jet and a potential circumstellar disk, providing evidence for a disk/jet system in early massive star formation.

Contribution

First detection of a thermal ionized jet and associated disk structure in G11.11-0.12P1 using VLA and UKIRT data, advancing understanding of early massive star formation.

Findings

Detected a string of four radio sources with positive spectral indices indicating an ionized jet.

Identified extended K-band structure possibly representing a circumstellar disk.

Provided evidence supporting the presence of a disk/jet system in a massive protostar.

Abstract

We report 1.3 cm and 6 cm continuum observations toward the massive proto-stellar candidate G11.11-0.12P1 using the Karl G. Jansky Very Large Array (VLA). We detect a string of four unresolved radio continuum sources coincident with the mid-IR source in G11P1. The continuum sources have positive spectral indices consistent with a thermal (free-free) ionized jet. The most likely origin of the ionized gas are shocks due to the interaction of a stellar wind with the surrounding high-density material. We also present NIR United Kingdom Infrared Telescope (UKIRT) archival data which show an extended structure detected only at K-band (2.2 $\mu$m), which is oriented perpendicular to the jet, and that may be scattered light from a circumstellar disk around the massive protostar. Our observations plus the UKIRT archival data thus provide new evidence that a disk/jet system is present in the massive protostellar candidate located in the G11.11-0.12P1 core.