James Webb Space Telescope captures the beauty of a rare, violent phenomena

Why does the universe have a 'dust surplus'? A pre-supernova star holds a clue.

By Purbita Saha

Posted on Mar 15, 2023 3:43 PM EDT

WR 145 star in pre-supernova state with white bright core and red and purple dust and matter clouding around it. Taken by NASA's James Webb Space Telescope.
Wolf-Rayet stars are known to be efficient dust producers, and the Mid-Infrared Instrument (MIRI) on NASA’s James Webb Space Telescope shows this to great effect. Cooler cosmic dust glows at the longer mid-infrared wavelengths, displaying the structure of WR 124’s nebula. The 10 light-years-wide nebula is made of material cast off from the aging star in random ejections, and from dust produced in the ensuing turbulence. This brilliant stage of mass loss precedes the star’s eventual supernova, when nuclear fusion in its core stops and the pressure of gravity causes it to collapse in on itself and then explode. Red marks the longest infrared wavelengths, green mid-length, and blue the shortest. NASA, ESA, CSA, STScI, Webb ERO Production Team

In the grand scheme of the universe and its stars, our sun isn’t all that powerful or special. While its death will certainly wreak havoc on the solar system, it isn’t big enough to trigger a supernova—one of the most violent cosmic phenomena we know of.

So, to understand what a star’s demise truly entails, astronomers have to zoom around to other parts of the galaxy with tools such as GAIA and the James Webb Space Telescope (JWST). One of the fascinating subjects they’ve keyed in on is WR 124, a “runaway star” that’s speeding away from home as it sheds gas, dust, and other stellar matter. Located at a distance of 15,000 light-years from Earth, it’s churning through a pre-supernova state that experts want to study up close.

A new JWST infrared image, captured last summer but shared publicly this week, exposes some of the explosive details scientists have been looking for. The telescope used a spectrograph and two of its advanced cameras to record the halo of dust emanating from WR 124. The star is currently in the “Wolf-Rayet phase,” in which it loses much of its mass to surrounding space. The bright white spot at the center shows the burning stellar core; the pink and purple ripples represent a nebula of hydrogen and other ejecta.

Stars of a certain magnitude will go through the Wolf-Rayet transformation as their lifespan winds down. WR 124 is one of the mightiest stars in the Milky Way, with 3,000 percent more mass than our sun. But its end is nye—it will collapse into a supernova in a few hundred thousand years

[Related: This could be a brand new type of supernova]

In the meantime, astronomers will use images and other data from JWST to measure WR 124’s contribution to the universe’s “dust budget.” Dust is essential to the universe’s workings, as NASA explains. The stuff protects young stars and forms a foundation for essential molecules—and planets. But much more of it exists than we can account for, the space agency notes: “The universe is operating with a dust budget surplus.”

The spectacular cloud around WR 124 might explain why that is. “Before Webb, dust-loving astronomers simply did not have enough detailed information to explore questions of dust production in environments like WR 124, and whether the dust grains were large and bountiful enough to survive the supernova and become a significant contribution to the overall dust budget. Now those questions can be investigated with real data,” NASA shared.

As JWST enters its second year of exploration, the observatory will take a sweeping look at galaxies far and near to reconstruct a timeline of the early universe. But individual stars can add to that cosmological understanding, too, even if they aren’t all on a glorious death march like WR 124.