You’re gonna die, cloud!
All stars, even our Sun, will someday eventually die.
Upon exhausting their core’s nuclear fuel, Sun-like stars die in a predictable fashion.
The core contracts, forming white dwarfs, which heats and illuminates the blown-off outer layers, creating planetary nebulae.
These nebulous remnants persist for ~20,000 years, experiencing slow, gradual changes.
After 20 years of Hubble observations, however, the Stingray Nebula appears doubly special.
First, it’s faded away tremendously, becoming far less luminous.
Second, the shells of gas are contracting and diffusing, appearing less crisp.
These changes are unprecedented, but different elemental signatures reveal clues.
Nitrogen and hydrogen emissions substantially decreased, but oxygen emissions plummeted almost a thousandfold.
This is driven by the central star’s temperature changes: rising from ~22,000 K to ~60,000 K previously, and now dropping rapidly.
At 50,000 K, oxygen loses two electrons, getting doubly ionized, emitting a brilliant green glow.
This hints at a recent burst of fusion: where helium in a shell around the core ignited, illuminating the surroundings.
With that burst over, the nebula fades as the central engine cools.
Additionally, the gas contracts instead of expanding: something never previously observed.
This planetary nebula could disappear entirely — a first — perhaps in merely 20–30 years.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.
Starts With A Bang is written by Ethan Siegel, Ph.D., author of Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive.