Yeah the wording is awkward; the supernova isn’t some sort of force of nature separate from the star that came and ripped it apart, it was the star ripping itself apart.
These are some of the first images we’ve probably inside the after effects due to the nature of the scope.
> “Shattered” seems like an odd way of describing it
Would love for an astrophysicist to pine in. But my understanding is supernovae are usually balanced enough to squeeze their stars' cores. This appears to have been unbalanced such that the core was "broken" instead of uniformly compressed.
Astrophysicist here :) You are correct in some way to say that the star "squeezes" the core. During the evolution of massive stars, say stars roughly 8 times as massive as our sun, the core grows to a point where it just cannot support itself. It collapses and in consequence triggers the type 2 supernova. Another commenter already mentioned correctly that the remnant of the explosion is typically a neutron star or a black hole. The asymmetries seen in the gaseous remnant are caused by the explosion, which typically is highly asymmetric for stars of larger mass (https://arxiv.org/abs/2005.02420, https://arxiv.org/abs/2112.09707) CasA was a IIb explosion and the neutron star was found in '99 and graciously called 'CXOU J232327.8+584842'. If you want to know more theory about supernovae I highly recommend https://arxiv.org/abs/1206.2503 and others :)
> There are also several light echoes visible in this image, most notably in the bottom right corner. This is where light from the star’s long-ago explosion has reached, and is warming distant dust, which is glowing as it cools down.
I'm looking at older pics of Cassiopeia A from the Hubble telescope, and it looks substantially different. How much time needs to pass before a supernova is visibly different? My instinct was that something like this would change over thousands of millions of years, but I'm guessing that's wrong
How quickly do the (damaging to nearby solar systems etc) effects of a supernova propagate through space, in relation to the speed of light?
Or, to put it another way, could we detect the damaging effects of a nearby supernova expanding towards us before those effects actually hit us? And if so, by what factor?
The radiation propagates at light speed, but the harmless neutrinos reach us a few hours before the potentially dangerous X-rays and gamma rays. A supernova would have to be within roughly 160 light years to be damaging to Earth.
> but the harmless neutrinos reach us a few hours before the potentially dangerous X-rays and gamma rays.
Huh? Presumably the electromagnetic radiation travels at the speed of light, and neutrinos travel more slowly; so the neutrinos arrive after the dangerous rays, not before.
You are correct that the radiation travels at the speed of light and the neutrinos less than that. The detail you’re missing is that the neutrinos depart the inner core of the star during the initial stages of the supernova and pass right through all of that material unimpeded. Though they travel at less than the speed of light, it’s not very much less, so the head start the neutrinos have allows them to arrive first.
Since the light emitted from the inner core during the supernova is instantly absorbed by the matter collapsing inward, it must be re-emitted and re-absorbed many times before it can reach open space and begin its journey to earth. With such an incredibly high density in the core of the collapsing star, the mean free path [1] of the light is extremely short, so this process can take a very long time.
So the early arrival of the neutrinos is entirely the result of EM radiation being absorbed within the star and re-emitted, while the neutrinos can pass straight through. I wondered if that was the explanation.
Yes. This same phenomenon is how we study gamma ray bursts. The neutrinos are detected early enough that the gamma ray detecting satellites have time to be pointed at the source. Otherwise they would be far too brief to observe!
They say the supernova happened 350 years ago; and that "Baby Cas A" is 170 light-years behind Cas A. So the echo "caught up" with light coming our way about 340 years ago; that is, the echo consists of light that was emitted just 10 years after the explosion.
Have I got that right?
[Edit] The "echo" isn't really a reflection; it's emission from a gas-cloud heated by the original explosion, as it cools down. So it's not really reflected light from the original event.
If you tell me about a supernova that "absolutely shattered" a star, you better be talking about a pair instability supernova or I'm going to be disappointed. I got excited thinking maybe they'd observed one.
Amazing photo. At the end of the Netflix documentary about JWST "Unknown: Cosmic Time Machine" they state the telescope data would be available for everyone to use. Is that actually true, or did they mean just these full res images?
I had a quick play with stuff around when the first images were announced. A ton of info is available including stages of processing, details on instruments, info (including Jupyter tutorials) on the Python calibration pipeline, etc. And of course how to access the data.
Here’s a fun theoretical existential threat: false vacuum decay. If our universe is in a false vacuum state (maybe yes? maybe no? we don’t know!) and that vacuum someday suddenly shifts into a true vacuum state (decays), then worst case scenario this change propagates everywhere instantaneously and we experience “complete cessation of fundamental forces” including elementary particles and structures. Everything everywhere wiped out in a blink.
We can take some comfort in the fact that we’d never know it happened, and theorists have asserted that it’s highly unlikely a false vacuum of any size could exist for more than a moment in the presence of gravitational forces, plus physics within the bubble would be “super weird”, I think is the technical term.
Isn't "false vacuum state" equivalent to a non-zero vacuum energy ? Which we know is the case, because virtual particle pairs blinking into and out of existence ? Did I leave something important out ?
Supernova are powerful enough that even a star in a different solar system going nova can kill you, if it's a "nearby" system. But I believe there aren't any stars close enough that would go supernova any time soon.
A good premise for a sci-fi series: In the distant future, a large fleet of earth's best and brightest travels the stars while desperately trying to invent Earth's last ditch-effort to save its 12 billion inhabitants from a soon-to-be cataclysmic, near-earth supernovae: FTL travel. After decades of progress finally nears fruition, the fleet permanently loses contact with earth; humanity's home Solar System's remnants lost to the beautiful, nightmare... The fleet of 80,000 now works to save itself, the last of humanity.
Sounds like Battlestar Galactica without the Cylons.
Perhaps the story could have Cylons in it, but here they're allies with the humans, but after the supernova, some religious leader convinces most of them that their god wants them to destroy the humans.
Sounds like a cross over of The Age of Supernova and Tri-body Problem.
In the former Supernova radiation kills all people on earth except kids under 13.
Every star that is not our sun is in a different solar system.
Could you have meant to say a star in a different galaxy could toast us?
I think, ball park, a SN 500 light years out is considered safe e.g. Betelgeuse.
Our Milky Way galaxy is thought to be roughly 100,000 light years in diameter
so we should be safe from all but those within about a hundredth of the radius
of our galaxy from us.
it makes me think of the flashes in the game of life! who knows how this released energy is going to affect the celestial objects nearby and these in turn affect other bodies and so on...
The part keeping a star together is its gravitational pull to all of its pieces. The part keeping it from collapsing is the outward push of its fusion (and also the electrons pushing against each other since they can't all occupy the same space).
This is usually balanced and you have a nice star. When the fusion slows as the star exhausts fuel, gravitational pull dominates and everything falls inward in a collapse. That presses the inner bits together nice and tight, and then the outer bits bounce off it.
So you have a collapse inward with an explosion as everything bounces off. Wikipedia has a nice picture.
The first time I came to understand this was in Isaac Asimov's The Collapsing Universe, which described how stars form, function, and die, with the ultimate fate of the very largest being black holes.
Stars are a contest between gravity and the nuclear strong force, with stellar fusion creating the heat and pressure required to resist, at least for a time, the pull of gravity. The larger a star, the faster it burns through its hydrogen fuel. While brown dwarf stars may have liftimes in the trillions of years, our Sun will expend all its fuel in about 11-12 billion years (it's about half-way through that process now), and will gradually grow hotter and brighter as it does so (it's already about 25% brighter than it was when the Earth was formed). The largest stars have lifespans of only a few million years, roughly dating to when the proto-hominids diverged from their last common ancestor with chimpanzees, and far more recently than the dinosaurs died out.
It's a useful lesson to recall that bigger and more energy-hungry does not necessarily mean longer-lived, and quite often means precisely the opposite.
I'm not an expert, but an analogy here could perhaps be if you drop a cup of water on the floor (assuming it doesn't break) some of that water is going to rebound on itself/the cup, and will splash upwards. That would be gravitational potential energy being converted to kinetic energy, causing material to be ejected.
With stars, there is a TON of gravitational potential energy, and so when it's converted to kinetic energy during a collapse, you "explode" the lighter weight outer layers of the star away from the more dense core. Some of the stars core remains, and can become either a neutron star or a black hole.
The original star has an "event horizon" in the sense of a Schwarzschild radius which would be interior to rhe star's full radius. The black hole's event horizon would be smaller in diameter than the original star simply because so much mass would have been ejected away.
Right, big explosion, easier to see. Typical solar toxicity. I can't wait for it to detect a gentle supernova, gently whisping a luliby to its exoplanets.
> Chandra’s study revealed the amounts of different elements produced by the explosion. The supernova has spat out 10,000 times the mass of the Earth in sulfur, 20,000 times Earth’s mass in silicon, 70,000 Earth masses of iron and a million Earth masses of oxygen.
