Water and Methanol Maser Activities in the NGC 2024 FIR 6 Region

TL;DR

This study investigates water and methanol maser activities in NGC 2024 FIR 6, revealing variable velocity components, associations with specific regions, and evidence of shocks from outflows or expanding H II regions.

Contribution

First detailed multi-frequency maser observations in NGC 2024 FIR 6, linking maser activity to local shocks and outflows, and characterizing their variability and velocity structures.

Findings

Water maser components show month-scale variability and velocity drifts.

Methanol masers are confined near the systemic velocity, indicating shock regions.

Most water maser components are associated with FIR 6n, one with FIR 4.

Abstract

The NGC 2024 FIR 6 region was observed in the water maser line at 22 GHz and the methanol class I maser lines at 44, 95, and 133 GHz. The water maser spectra displayed several velocity components and month-scale time variabilities. Most of the velocity components may be associated with FIR 6n, while one component was associated with FIR 4. A typical life time of the water-maser velocity-components is about 8 months. The components showed velocity fluctuations with a typical drift rate of about 0.01 km/s/day. The methanol class I masers were detected toward FIR 6. The methanol emission is confined within a narrow range around the systemic velocity of the FIR 6 cloud core. The methanol masers suggest the existence of shocks driven by either the expanding H II region of FIR 6c or the outflow of FIR 6n.