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JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

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Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#51

Post by thaumasiotes »

its_ethan wrote: post #38
deskamess wrote: post #34

> The star collapses in an explosion Can anyone explain the above phrase?

This might be helpful: https://en.wikipedia.org/wiki/Supernova#Core_collapse 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 T…

> Some of the star's core remains, and can become either a neutron star or a black hole.

Just to be sure I understand, the event horizon of the new black hole would have to lie within the interior of the original star, right?

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#52

Post by gratitoad »

mensetmanusman wrote: post #7

It's kind of fun to think that at any moment something might pop and our entire solar system would disappear in a blink of an eye.

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.

https://en.m.wikipedia.org/wiki/False_vacuum#Existential_thr...

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#53

Post by doctoboggan »

AlecSchueler wrote: post #42
aeonik wrote: post #41

Earlier quoted context omitted.

I presume they mean in the sky. Not sure if anyone is relaying it over the Internet, but I looked it up, and the remnants will last for at the very least hundreds of years: https://en.wikipedia.org/wiki/Supernova_remnant

Ah but nowhere to see a livestream of from JWST right now?

No, in general it isn't possible to livestream images like this because they are usually captured as very long exposures measured in hours or days.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#54

Post by altcognito »

hinkley wrote: post #9
squigz wrote: post #2

Isn't that what every supernova does?

I thought, surely they mean a supernova obliterated a companion star, but you’re right. They’re talking about the exploding star. Is this noteworthy because we’ve seen it, rather than that it exists? How many novae cores have we imaged before?

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.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#55

Post by bmitc »

tejtm wrote: post #48
TheEzEzz wrote: post #11

Earlier quoted context omitted.

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.

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. space is big ...

I don't think they were using the solar system, as in our solar system, as their frame of reference.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#56

Post by bmitc »

thaumasiotes wrote: post #51
its_ethan wrote: post #38

Earlier quoted context omitted.

This might be helpful: https://en.wikipedia.org/wiki/Supernova#Core_collapse 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 T…

> Some of the star's core remains, and can become either a neutron star or a black hole. Just to be sure I understand, the event horizon of the new black hole would have to lie within the interior of the original star, right?

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.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#57

Post by andrewflnr »

AlecSchueler wrote: post #40
humble_ant wrote: post #30

Fair to say this happened 11,000 years ago?

Equally fair to say it's happening right now depending on your frame of reference.

No it's not. That's not what a reference frame is. Stars in the Milky Way are in approximately the same reference frame as Earth.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#58

Post by andrewflnr »

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.

https://en.wikipedia.org/wiki/Pair-instability_supernova

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#59

Post by denton-scratch »

The "light echo" is interesting.

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.

Re: JWST Captures Image of Supernova That 'Absolutely Shattered' a Star

#60

Post by denton-scratch »

Scaevolus wrote: post #37
crtified wrote: post #33

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. https://news.fnal.gov/2019/03/waiting-for-neutrinos/ https://earthsky.org/astronomy-essentials/safe-distance-from...

> 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.

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