“Water-Fountain Stars” –Rare Image from Chile’s ALMA Observatory

W43A Water Star

 

W43A is a peculiar star, a so called ‘water-fountain’ object, says Hiroshi Imai at Kagoshima University, Japan. “Some old stars show characteristic radio emissions from water molecules. We suppose that spots of these water emissions indicate the interface region between the jets and the surrounding material. We named them “water fountains,” and it could be a sign that the central source is a binarity system launching a new jet.”

ALMA image of the old star system W43A. The high velocity bipolar jets ejected from the central aged star are seen in blue, low velocity outflow is shown in green, and dusty clouds drawn in by the jets are shown in orange. The image captured the exact moment when an old star first starts to alter its environment by ejecting high-speed bipolar gas jets which collide with the surrounding material. The age of the observed jet is estimated to be less than 60 years

“There are only 15 ‘water fountain’ objects identified to date, despite the fact that more than 100 billion stars are included in our Milky Way Galaxy,” explains José Francisco Gómez at Instituto de Astrofísica de Andalucía, Spain. “This is probably because the lifetime of the jets is quite short, so we are very lucky to see such rare objects.”

These observation results were presented in D. Tafoya et al. “Shaping the envelope of the asymptotic giant branch star W43A with a collimated fast jet” published by the Astrophysical Journal Letters on February 13, 2020.

The Daily Galaxy via ALMA Observatory

Image credit: ALMA (ESO/NAOJ/NRAO), Tafoya et al