JWST sees dust in a phenomenally violent cosmic flower

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One oxymoronic aspect of loving astronomy is being simultaneously attracted to and repelled by some cosmic objects.

I have always been fascinated by supernovae: stars that explode. They come in a lot of different flavors, but the old reliable stereotype is a massive star that lives fast and dies young, running through its nuclear fuel in a few million years and exploding in an event so ridiculously apocalyptic that it completely grinds our brains into dust.

Imagine a single star blasting out a hundred million trillion times as much energy as the Sun does over a few seconds, and you’re just starting to understand what we’re dealing with here.

What kind of star can do that? It needs to have at least 8 times the mass of the Sun or else it can’t generate the pressure needed in its core to set up the supernova conditions. Some stars are far more massive than that, too, up to several dozen solar masses.

The energy (think of it as light) these stars put out even before they explode is staggering. Their luminosity — the amount of energy they emit per second — increases with mass by the power of more than 3: A star twice as massive as the Sun emits >10 times as much energy. A star 20 times its mass blasts out ~50,000 times as much energy. Other factors come into play too, and some stars can shine even more intensely.

And then there are Wolf-Rayet stars. They’re similar to other massive stars, but they are on their way out: They’ve run out of hydrogen in their cores to fuse into helium, and are now fusing heavier elements like helium or carbon. This generates whopping amounts of energy, and WR stars, as they’re called, can blast out hundreds of thousands of times the energy of the Sun. Replace the Sun in our solar system with one of these and the Earth would be cooked. Heck, I bet it would melt Jupiter’s icy moons.

They are so luminous that they have a hard time holding on to their outer layers. They blow out a fierce wind of material from their surfaces, what’s called a stellar wind or stellar outflow. A huge amount of gas screams away from the star, sometimes multiple times the mass of our Sun, flying away at extremely high speed.

What would something like that look like?

This. It looks like this.

That is the Wolf-Rayet star WR124 (the bright one in the middle) flinging out tremendous amount of gas to form the nebula M1-67. It looks like some sort of astronomical flower, but don’t be fooled: The amount of gas in the nebula could be as much as nine times the mass of the Sun. Just in the gas being blasted outwards. And the speed of the gas? Well over 300,000 kilometers per hour!

The amount of energy needed to accelerate that amount of material to that speed — a hundred times faster than a rifle bullet — well, it grinds my brain into dust.

This image was taken by JWST, and shows infrared light coming from the star and material around it. It combines the images from two cameras: The Near Infrared Camera (NIRCAM), which sees light with wavelengths just outside the range of the human eye, and the Mid-Infrared Instrument (MIRI) which sees even longer wavelengths. Dust — tiny grains of rocky and/or sooty material — emits light at those longer wavelengths, so MIRI sees it pretty well. Here’s the MIRI image alone:

You can see a shell of material forming a ring around the outside of the nebula. WR 124 sits in the plane of the Milky Way, meaning there’s a lot of interstellar material floating around like thin fog surrounding it. As the hugely rapid matter expelled from the star slams into the pre-existing stuff, it piles up like snow in a snowplow shovel.

Inside there are a lot of little fingers pointing away from the central star. Those are probably dense knots, clumps of material, slammed by the torrential onslaught of matter and energy from the star. Dust in the clump is picked up and flows away “downstream”, forming the long comet-like tail. Over time, these clumps evaporate as their material is blown away.

How big is this nebula physically? That’s not clear. I’ve seen distance estimates for WR 124/M1-67 of 10,000 light-years, in which case the cloud would be about 6 light-years wide. I’ve also seen 20,000 light-years for a distance in which case the nebula is twice as large. Some material extends even further, so either way: it’s huge.

How exactly massive stars make dust isn’t well understood. We do know that when stars like the Sun start to die and expand into red giants, they produce dust. When more massive stars turn into red supergiants (like Betelgeuse) they make prodigious quantities of dust (which is why Big B dimmed so much a couple of years ago, in fact). But the details of the process still need to be figured out. Images like these from JWST will help. Mapping the dust location, its brightness, and its structure give hints about what’s happening deep inside the star; the chemistry and physics that blows out so must dust you could make tens of thousands of Earths from it.

By the way, Hubble observed this same star/nebula and also took a really dramatic image of it:

At visible light wavelengths (shorter than infrared), gas dominates the view. As it slams into the material around it tremendous turbulence is generated, creating much of the incredible structure you see.

By the way: WR 124 is nearing the end of its life, and will someday — probably in a few hundred thousand years — explode. It’s too far away to affect us physically, but when it does go all supernova it’ll dwarf the energy its emitting now. Just so’s you know.

Which brings me back to my opening point. These Wolf-Rayet stars are absolutely terrifying. They toss around energy and forces and matter on scales that crush anything we humans are accustomed to, creating chaos and violence all around themselves for trillions of kilometers.

And yet, from quadrillions away, they are nothing short of jaw-droppingly gorgeous.

Of all the internal dichotomies of astronomy, this one is my absolute favorite.

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