This illustration shows a proposed model for a mysterious astronomical event called a Fast-Evolving Luminous Transient (FELT). In the left panel, an aging red giant star loses mass via a stellar wind. This balloons into a huge gaseous shell around the star. In the center panel, the massive star's core implodes to trigger a supernova explosion. In the right panel, the supernova shockwave plows into the outer shell, converting the kinetic energy from the explosion into a brilliant burst of light. The flash of radiation lasts for only a few days — one-tenth the duration of a typical supernova explosion. Credit: NASA, ESA, and A. Feild (STScI)
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