44 votes
Accepted

Are there observable changes in a star about to become supernova, minutes or hours before the explosion?

I think your best bet would be detecting neutrinos generated by nuclear burning inside the star (as we do for the Sun). Once the star hits the carbon-burning stage, it's actually putting out more ...
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40 votes

Did I see a supernova explosion?

Supernovae increase in brightness over several days and decrease over months. Thus, whatever you saw, was not a supernova, sorry.
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34 votes

Did I see a supernova explosion?

I don't know about your country, but in the United States the major weather services launch instrumented balloons twice a day. They are about 1 or 2 meters in diameter. We often see them in the ...
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33 votes
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Why do stars explode?

Short answer: A tiny fraction of the gravitational potential energy released by the very rapid collapse of the inert iron core gets transferred to the outer layers and this is sufficient to power ...
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25 votes
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Explosions of black holes

What this video is talking about is Hawking Radiation, as you've linked. Hawking Radiation is a proposed hypothetical (by no means verified or proven) way for a black hole to radiate its energy into ...
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19 votes

Are there observable changes in a star about to become supernova, minutes or hours before the explosion?

Other answers are correct; a neutrino pulse is definitely expected as a result of a core-collapse supernova and should occur some hours before a shockwave arrives at the surface. There essentially ...
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  • 117k
19 votes
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Why does matter stay collapsed in the core, following a supernova explosion?

In order to "blow something up" you need to release more energy than its binding energy and have a way of trapping that energy so it can't escape in another way. At the centre of a core collapse ...
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  • 117k
12 votes
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Can a black hole "supernova"?

No, it cannot. A black hole is something vastly different from a star. It's vastly different from anything else. It's not a thing, really, but more like a portion of very distorted spacetime. Nothing ...
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11 votes

Are there observable changes in a star about to become supernova, minutes or hours before the explosion?

As Dean said, supernova progenitors typically release neutrinos prior to full core collapse, remnant formation and the ejection of the outer layers of the star. The process - focused here on the ...
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11 votes

Why are type 1b and type 1c supernovae called type 1 rather than type 2; if they result from large exploding stars, rather than accreting dwarfs?

It is fundamentally a question of spectral lines. Type I supernovae have no hydrogen lines, and type II have strong hydrogen lines. Type 1b have strong helium lines and no hydrogen lines, and type 1c ...
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10 votes

Did I see a supernova explosion?

The Hubble telescope has a resolution of about 1/20 of an arcsecond, or 1/25920000 of a circle. A Julian year has 31557600 seconds. This means for something a light year away, it would take 1.2175 ...
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9 votes

Why doesn't the Sun explode?

There are two things to discuss here: (a) why the Sun does not explode; and (b) why the Sun will not explode. (a) An explosion occurs when the timescale for the energy release by some process is much ...
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  • 117k
9 votes
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What would the effects on or around Earth if Betelgeuse went supernova?

tl;dr - The main measurable effect may be minor climate cooling, but in day-to-day life, the only difference would be that we see a cool, bright explosion in the sky, and eventually, Orion becomes "...
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8 votes
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If Betelgeuse is exploding in 2022, why would we see the explosion in 2022?

Light travels at a finite speed, 299 792 458 meters per second. Hence the term light year is the distance it takes light to travel in one year. Most of what is observed in the cosmos occurred some ...
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7 votes

Did I see a supernova explosion?

I was involved in a volunteer project which searched for new supernovas and was one person of several who identified SN 2016 dln as a new supernova. Identifying the possible supernovas was quite ...
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7 votes

Why does matter stay collapsed in the core, following a supernova explosion?

What's missing from the above explanations is what is really going on that causes any kind of explosion at all. I'm going to steal from xkcd to help with this: https://what-if.xkcd.com/73/ And here'...
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6 votes

If Betelgeuse is exploding in 2022, why would we see the explosion in 2022?

Has Beteleguse exploded? No, as we have not seen the explosion. From the reference frame of the Earth we have not seen it explode (yet). It does not matter that in Betelgeuse's frame it may have ...
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5 votes
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Speed of blast from supernova

The speed of the blast front depends on the initial energy release and the density of the medium into which it is expanding, see here. Theory suggests and measurements confirm expansion rates of the ...
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4 votes

Can a black hole "supernova"?

One other supernovae-like but not a supernovae is a tidal disruption event. If a star passes close enough to a black hole it can be fully disrupted into a stream of gas. As the material passes its ...
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  • 1,271
4 votes

Why do stars explode?

To give an answer in more simple turns. (Yes very simplified, but it should introduce the basic concept). A Star "burns" by nuclear fusion between lighter elements such as Hydrogen turning to Helium. ...
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3 votes
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Why doesn't the Sun explode?

Our sun is a particularly average sized star on the main sequence. It is not going to ever go "supernova" but instead will slowly swell and darken towards red, eventually swallowing Mercury and Venus. ...
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2 votes

Exploded star or object on earth?

Jupiter it is (moved from comment)
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2 votes

Did I see a supernova explosion?

Many have. Unfortunately, you probably haven't. I have to check my dates, yet, I believe the last seen, was in '80-ish. An apparent supernova would be the most distinguished sight in the sky. Ancient ...
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2 votes

Supernova explosion nearby

The Chandrasekhar limit in general does not pertain to the mass of the star as a whole. It addresses the mass of the degenerate core. It's only in white dwarfs where the Chandrasekhar limit applies to ...
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2 votes
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Supernova explosion nearby

The Chandrasekhar limit applies only for white dwarfs. Stars on the main sequence (or even off the main sequence) can easily surpass it, but if a white dwarf's mass is greater than the Chandrasekhar ...
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2 votes

Why does matter stay collapsed in the core, following a supernova explosion?

Found the answer on NASA site The collapse happens so quickly that it creates enormous shock waves that cause the outer part of the star to explode! This means the core survives the blast somehow
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2 votes

Why doesn't the Sun explode?

Whether a star explodes or not is given by how quickly nuclear fusion happens inside it. If fusion takes place at a steady pace, the star does not explode. If lots of material fuse at once, the star ...
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1 vote

Why doesn't the Sun explode?

Our sun (I'm assuming you're from Earth or at least the solar system) is actually not all that big, compared to other stars. The gravitational pull of the mass of the sun is kept in check by the ...
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1 vote

Are there observable changes in a star about to become supernova, minutes or hours before the explosion?

A superluminous supernova (aka hypernova) can exhibit a double peak to its brightness and some are theorizing that this may be the norm for a superluminous supernova, though as far as I know it's only ...
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1 vote

Why is iron responsible for causing a supernova?

The most important reason that core collapse happens is that particles moving close to the speed of light are notoriously gravitationally unstable. That's because when particles moving slower than ...
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