The Ionized Nebula surrounding the Red Supergiant W26 in Westerlund 1

Abstract

We present Hαimages of an ionized nebula surrounding the M2-5Ia red supergiant (RSG) W26 in the massive star cluster Westerlund 1. The nebula consists of a circumstellar shell or ring ~0.1pc in diameter and a triangular nebula ~0.2pc from the star that in high-resolution Hubble Space Telescope images shows a complex filamentary structure. The excitation mechanism of both regions is unclear since RSGs are too cool to produce ionizing photons and we consider various possibilities. The presence of the nebula, high stellar luminosity and spectral variability suggest that W26 is a highly evolved RSG experiencing extreme levels of mass-loss. As the only known example of an ionized nebula surrounding a RSG W26 deserves further attention to improve our understanding of the final evolutionary stages of massive stars.

6 pages, 4 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society

References in corpus (7)

• Intermediate to low-mass stellar content of Westerlund 1
• The IPHAS Catalogue of Halpha Emission Line Sources in the Northern Galactic Plane
• Diffuse, Non-Thermal X-ray Emission from the Galactic Star Cluster Westerlund 1
• Spatially resolved dusty torus toward the red supergiant WOH G64 in the Large Magellanic Cloud
• Medium resolution 2.3 micron spectroscopy of the massive Galactic open cluster Westerlund 1
• The Physical Properties of the Red Supergiant WOH G64: The Largest Star Known?
• Near-infrared photometry of Galactic planetary nebulae with the VVV Survey

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• A VLT/FLAMES survey for massive binaries in Westerlund 1 V. the X-ray selected blue stragglers Wd1-27 and -30a
• Discovery of a new classical nova shell around a nova-like cataclysmic variable
• Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1
• Investigating dusty Red Supergiant outflows in Westerlund 1 with 3D Hydrodynamic simulations
• First Discovery and Confirmation of PN Candidates Found from AI and Deep Learning Techniques Applied to VPHAS+ Survey Data
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