Discovery of SiO Masers in the “Water Fountain” Source IRAS 16552−3050

K Amada,L Uscanga,K Nakashima,H Imai,D Tafoya,R A Burns,Y Hamae,J F Gómez,G Orosz,K Y Shum

doi:10.3847/1538-3881/ac3fb6

Abstract

Abstract In this paper, we report new detections of SiO v = 1 and v = 2 J = 1 → 0 masers in the “water fountain” source IRAS 16552−3050, which was observed with the Nobeyama 45 m telescope during 2021 March–April. Water fountains are evolved stars whose H2O maser spectra trace high-velocity outflows of >100 km s−1. This is the second known case of SiO masers in a water fountain, after their prototypical source, W 43A. These SiO masers should shed light on the evolutionary status of this category of evolved stars, which are likely to be at the end of the asymptotic giant branch phase, when the star exhibits the most copious stellar mass loss, followed by development of the complicated morphologies of planetary nebulae. The origin of a large (up to 25 km s−1) velocity offset of the SiO masers with respect to the systemic velocity derived from the spectrum of CO J = 2 → 1 line is discussed here.

Highlights

SiO maser emission is one of the key probes of the status of the stellar mass loss as seen in objects in the asymptotic giant branch (AGB) phase and, in a limited number of cases, in the post-AGB phase (e.g., Gonidakis et al 2013)
We report new detections of SiO masers in IRAS 16552−3050
No OH maser emission was found (Hu et al 1994) this is common among AGB stars

Summary

Introduction

SiO maser emission is one of the key probes of the status of the stellar mass loss as seen in objects in the AGB phase and, in a limited number of cases, in the post-AGB phase (e.g., Gonidakis et al 2013). The presence of SiO maser emission, together with the periodic variation of the OH masers at 1612 MHz (Herman & Habing 1985), provide strong evidence that the central system hosts an AGB star with a high mass-loss rate (see Tafoya et al 2020).

Results

Conclusion