183 GHz H$_2$O maser emission around the low-mass protostar Serpens SMM1

TL;DR

This study reports the first interferometric detection of 183 GHz water maser emission around the low-mass protostar Serpens SMM1, revealing small, bright maser spots along the outflow, likely originating from cavity wall interactions.

Contribution

First interferometric detection of 183 GHz water masers in a low-mass protostar, providing spatial localization and insights into their origin within outflow cavity walls.

Findings

Detected three maser spots within 700 AU of the protostar.

Masers are aligned along the red-shifted outflow axis.

No thermal envelope emission was detected, supporting maser origin hypotheses.

Abstract

We report the first interferomteric detection of 183 GHz water emission in the low-mass protostar Serpens SMM1 using the Submillimeter Array with a resolution of 3$"$ and rms of $\sim$7 Jy in a 3 km s$^{-1}$ bin. Due to the small size and high brightnessof more than 240 Jy/beam, it appears to be maser emission. In total three maser spots were detected out to $\sim$ 700 AU from the central protostar, lying along the red-shifted outflow axis, outside the circumstellar disk but within the envelope region as evidenced by the continuum measurements. Two of the maser spots appear to be blue-shifted by about 1 to 2 km s$^{-1}$. No extended or compact thermal emission from a passively heated protostellar envelope was detected with a limit of 7 Jy (16 K), in agreement with recent modelling efforts. We propose that the maser spots originate within the cavity walls due to the interaction of the outflow jet with the surrounding protostellar envelope. Hydrodynamical models predict that such regions can be dense and warm enough to invert the 183 GHz water transition.