Registration of H${}_2$O and SiO masers in the Calabash Nebula, to confirm the Planetary Nebula paradigm

Abstract

We report on the astrometric registration of VLBI images of the SiO and water masers in OH231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the AGB star, driving the bi-lobe structure with the water masers in the out-flow. We are able to trace the bulk motions for the water masers over the last few decades to be 19 km/s and deduce that the age of this expansion stage is 38$\pm$2 years. The combination of this result with the distance allows a full 3D reconstruction, and confirms that the water masers lie on and expand along the known large-scale symmetry axis and that the outflow is only a few decades old, so mass loss is almost certainly on-going. Therefore we conclude that the SiO emission marks the stellar core of the nebular, the water emission traces the expansion, and that there must be multiple epochs of ejection to drive the macro-scale structure.

arXiv commentFigure 6 is 3D

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Cited by in corpus (5)

• Through the magnifying glass: ALMA acute viewing of the intricate nebular architecture of OH231.8+4.2
• Time variations of H2O and SiO masers in the proto-Planeatry Nebula OH231.8+4.2
• ALMA reveals the coherence of the magnetic field geometry in OH 231.8+4.2
• Long-term Simultaneous Monitoring Observations of SiO and H2O Masers toward the Mira Variable WX Serpentis
• On the Nature of the Protoplanetary Nebula OH\,231.8+4.2