The intrepid James Webb Space Telescope (JWST) has captured a stunning infrared view of a dynamic planetary nebula roughly 4,200 light-years away in the constellation Gemini (NGC 2392), with its latest images revealing intricate dusty filaments and expanding plasma shells.

First discovered in 1787 by astronomer William Herschel and famously imaged in visible light by the Hubble Space Telescope in 2000, NGC 2392 is historically known as the Eskimo Nebula or Clownface Nebula, and more recently as the Lion Nebula. Where Hubble photos showed a glowing, atmospheric ring, Webb’s combined Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) observations cut through the dust to expose the violent mechanics sculpting the system from the inside out.

At the center of NGC 2392 is an oxygen-rich, lower-mass star that ran out of nuclear fuel, and because it was unable to sustain fusion, the dying star began pulsating and shedding its outer layers into surrounding space over several thousand years. The remaining core has compressed into a white dwarf, serving as an engine that drives intense radiation into the ejected material. This photon bombardment superheats and ionizes the surrounding gas, carving out an expanding bubble.

NIRCAM and MIRI composite of the Lion Nebula - Image: NASA, ESA, CSA, STScI

In Webb’s latest capture, this ionized plasma bubble is framed by delicate arcs of gas that visually evoke its latest namesake. As the superheated gas expands, it's creating a shock front that destroys loose particulate dust along its path. Encircling this inner cavity is a thick, highly structured shell of cooler gas and dust, illuminated by the central white dwarf to create the appearance of a majestic mane.

Within this outer mane, Webb’s optics shows off dense, compact clumps of dust that have withstood the central star’s harsh radiation pressure. These stubborn knots block the high-energy photons, protecting the material directly behind them and drawing out long, comet-like tails of cool gas and dust. 

In the meantime, astronomers are closely analyzing these radial tail structures, although they might have to do it quick as experts estimate that the Lion Nebula will completely dissipate within approximately 10,000 years, which is a brief episode in the big scheme of things.

AL