# Milliarcsecond structure of water maser emission in two young high-mass stellar objects associated with methanol masers

**Authors:** Anna Bartkiewicz, Marian Szymczak, Huib Jan van Langevelde  
**arXiv:** [1204.0806](https://arxiv.org/abs/1204.0806)  
**Date:** 2012-04-03  
**Summary page:** https://www.summarizepaper.com/en/paper/1204.0806v1/

## Key points

- 22.2 GHz water masers and 6.7 GHz methanol masers are often found together
- They likely originate from different regions around young massive stars due to different excitation conditions
- High-angular and spectral resolution 22.2 GHz water maser observations were conducted on two sources, G31.581+00.077 and G33.641-00.228, using the EVN
- Water maser spots in both objects form complex and filamentary structures ranging in size from 18 to 160 AU
- Emission towards G31.581+00.077 originates from two distinct regions, one related to the ring-like shape of the methanol maser source
- Main axis of methanol distribution is orthogonal to the water maser distribution in both targets
- Water masers appear to trace shocks on a working surface between an outflow/jet and a dense envelope surrounding the young massive star
- Some spots may be associated with the disc-wind interface, as close as 100-150 AU to regions of methanol emission
- Findings provide insights into spatial and kinematic characteristics of water and methanol masers around young high-mass stellar objects

## Summary

The 22.2 GHz water masers and 6.7 GHz methanol masers are often found together, but they likely originate from different regions around young massive stars due to their different excitation conditions. In order to understand the structures in which these masers arise and test a disc-outflow scenario where methanol emission comes from a circumstellar disc and water emission comes from an outflow, high-angular and spectral resolution 22.2 GHz water maser observations were conducted on two sources, G31.581+00.077 and G33.641-00.228, using the EVN. The results revealed that the water maser spots in both objects form complex and filamentary structures ranging in size from 18 to 160 astronomical units (AU). The emission towards G31.581+00.077 originates from two distinct regions, with one region being related to the ring-like shape of the methanol maser source. Interestingly, the main axis of methanol distribution is orthogonal to the water maser distribution in both targets. Most of the water masers appear to trace shocks on a working surface between an outflow/jet and a dense envelope surrounding the young massive star. Some spots may also be associated with the disc-wind interface, which can be as close as 100-150 AU to the regions of methanol emission. Overall, these findings provide valuable insights into the spatial and kinematic characteristics of water and methanol masers around young high-mass stellar objects, suggesting that they arise from different physical processes within star-forming regions that can be used as probes for studying various phenomena associated with massive star formation.