Water Maser Survey towards off-plane O-rich AGBs around the orbital plane of the Sagittarius Stellar Stream

TL;DR

This survey of 178 O-rich AGB stars detected 21 water masers, revealing their Galactic distribution and motions, but found no clear association with the Sagittarius stellar stream, instead indicating they are Galactic disc sources.

Contribution

First water maser survey targeting off-plane O-rich AGBs around the Sagittarius stream, providing new detections and insights into their Galactic distribution and kinematics.

Findings

21 water masers detected, 20 new

AGBs form an elongated structure near the Sgr stream

AGBs are Galactic disc sources with outward motion

Abstract

A 22 GHz water maser survey was conducted towards 178 O-rich AGB stars with the aim of identifying maser emission associated with the Sagittarius stellar stream. In this survey, maser emissions were detected in 21 targets, of which 20 were new detections. We studied the Galactic distributions of H2O and SiO maser-traced AGBs towards the Sgr orbital plane, and found an elongated structure towards the (l, b)~(340, 40) direction. In order to verify its association with the Sagittarius tidal stream, we further studied the 3D motions of these sources, but found, kinematically, these maser-traced AGBs are still Galactic disc sources rather than Stream debris. In addition, we found a remarkable outward motion, ~50 km/s away from the Galactic center of these maser-traced AGBs, but with no systermatic lag of rotational speed which were reported in 2000 for solar neighborhood Miras.