A dying star molting its final layers in space seems to be in the midst of a sad, solitary experience — at least from a storytelling perspective.
But a new image from the James Webb Space Telescope, a collaboration of NASA and its European and Canadian counterparts, shows this drama isn't a one-star act. More than one stellar object, at least for this scene, is on the playbill.
In a new look at the planetary nebula NGC 6072, located about 3,800 light-years away in the constellation Scorpius, astronomers found evidence that this cosmic cloud's chaotic, lopsided shape is likely the handiwork of more than one star. The tangle of glowing gas may actually reveal a star in its final stages — with a companion sticking by its side until the proverbial curtain falls.
The results of the observation help astronomers understand how some stars die, especially in multiple-star systems, which are thought to be more prevalent in the Milky Way than solo star solar systems.
Unlike giant stars that explode into a supernova and collapse into a black hole, a medium star like the sun is expected to just keep on burning until its nuclear fuel peters out, suffering a more prolonged death.
This event forms a so-called "planetary nebula," a confusing misnomer for the phenomenon because it has more to do with an aging star than planets. As a sun-like star nears the end, it puffs out into a red giant — about 100 to 1,000 times its original size — eventually engulfing the space around it, including any nearby worlds.
As the star eventually releases its outer layers, it shrivels down to its core in what's known as a white dwarf star. At that point, it'll be about the size of Earth.
Webb’s powerful infrared instruments took this new high-resolution image of NGC 6072, which doesn't have a fun nickname like some other planetary nebulas. The picture shows multiple lobes of material bursting outward at odd angles like fireworks. It's a far cry from the smooth, evenly distributed rings once expected of such end-of-life events from stars similar in mass to the sun.
Astronomers say telltale signs point to this being a binary system: two stars; one dying, the other disrupting the event with its gravity.
Webb's Near-Infrared Camera view shows at least two or three distinct outflows of gas — jets stretching in different directions — plus a disk of compressed material forming along the middle, likely caused by winds blasting through older shells of expelled gas.
But it’s the companion star that can't be directly seen that's grabbing astronomers' attention. The view taken by Webb's Mid-Infrared Instrument, aka MIRI, shows expanding concentric rings around the dying central star, which astronomers suspect is a pinkish-white dot in the middle of the image. The rings could have been carved out as the hidden secondary star repeatedly circled its partner, plowing through the fading outer layers.
One of Webb's first images was of the Southern Ring Nebula, about 2,500 light-years away. Astronomers had suspected for more than 50 years that there were actually two stars at its core, but they hadn't actually seen the dimmer star — the true source of the nebula — until they pointed the telescope's camera at it, said Karl Gordon, an astronomer at the Space Telescope Science Institute in Baltimore. In that case, it was the opposite: They could see the companion but not the dying star.
"We knew this was a binary star (beforehand), but we effectively didn't really see much of the actual star that produced the nebula," Gordon said during a 2022 news conference. "But now in MIRI, this star glows red because it has dust around it."
With prior Hubble Space Telescope observations, astronomers found many irregularly shaped planetary nebulas influenced by a second star — so many, in fact, they began to wonder if the extra star was actually a crucial component for their creation, said Rodolfo Montez, who studies dying sun-like stars at the Harvard and Smithsonian Center for Astrophysics.
"It's called a binary hypothesis, which would suggest that [only] stars in binary systems make planetary nebulae," Montez previously told Mashable. "But then we're not clear what single stars like our sun would do in that framework."
Each lobe, arc, and filament deepens the mystery of how stars like — or perhaps not quite like — the sun die.
But one thing scientists do know: When the glowing cloud of NGC 6072 finally dissipates, it'll leave behind a scattering of heavy elements, perhaps seeding a new generation of mind-boggling stars and planets.
