42

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 energy in neutrinos than in photons. During the silicon-burning phase, which lasts for a few days and is what creates the degenerate iron core (that collapses once ...


40

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


34

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 evening at the observatory, and your description matches. A bright star visible to the unaided eye in the twilight. The balloon and instruments hanging beneath the ...


33

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 the observed explosion. In more detail: Consider the energetics of an idealised model star. It has a "core" of mass $M$ and initial radius $R_0$ and an outer ...


25

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 space. The basic idea is that a black hole is nothing but mass/energy compressed to an infinitesimal point, which is radiating its energy into space over time. ...


19

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 supernovae is a 10 km radius, $1.4 M_{\odot}$ ball of (almost) neutrons. Its gravitational binding energy is $\sim GM^2/R = 5\times 10^{46}$ J. This is almost ...


17

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 would be no visible sign that the star was about to become a supernova and that is because the dynamical timescale of the envelope is relatively long - thus ...


13

Your question is a bit oversimplified because there are many types of supernovae based on the size and configuration of the star. But I can answer your question about "why iron" by considering what keeps a star from exploding in the first place. In the simplest terms of star formation, when material from an interstellar nebula starts to collapse under its ...


12

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 escapes from it simply because there is no way out - spacetime is distorted in such a way that all trajectories lead to the center. Now, there is a mechanism ...


11

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 neutrinos - goes something like the following: At high enough densities ($\rho\sim10^9\text{ g/cm}^3$), electron capture becomes important, where a proton and ...


11

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 have neither helium nor hydrogen lines. That’s why they aren’t designated as type II supernovae. The reason why type 1b and 1c supernovae have no hydrogen lines ...


10

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 seconds for an object to move far enough for its motion to be resolved by the Hubble telescope, even if it were traveling at the speed of light. (And by that, I ...


9

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 shorter than the timescale on which a system can adjust to damp the energy release process. In the present day Sun, nuclear fusion is a very slow process: on ...


9

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 "incomplete". The effects would likely be quite minimal. What Will Happen When Betelgeuse Goes Supernova? by Corey S. Powell, former editor in chief of Discover ...


7

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's an article from the Max Planck Institute that talks in depth about the nature of the neutrino aspect: https://www.mpg.de/11368641/neutrinos-supernovae ...


7

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 delicate and required a lot of hours and practice, and so I suspect (also taking into account your description) that what you saw was likely not a supernova and was ...


7

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 time ago. The more distant an object is the longer it has taken for the light from that object to reach our location. If Betelgeuse has exploded we don't know ...


5

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 order of thousands of km/s or a few $\times 10^6\ \mbox{m/s}$ or $\sim 1\% \mbox{c}$.


5

The binding energy per nucleon is among the highest for iron-56. Therefore nuclear fusion as well as fission/photodisintegration of iron-56 consumes energy. Heat production is needed to prevent a star from collapsing to a much denser state. Iron-56 provides no way to produce heat by nuclear reactions. Hence core collapse is unavoidable. If the star isn't ...


5

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 exploded already. When people discuss what happens to any object in the Universe we are always talking about what we have seen on Earth. Just because it takes a long ...


4

I guess one of them you're referring to was GRB 130427A (not in December of 2010 or 2011 tho, but in April 2013)? But yes, there are several such catalogs, as are different designators and phenomenological classification methods for these gamma-ray bursts (GBR). For example, GRB 130427A is a simple nomenclature that consists of a date of discovery (130427 ...


4

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 closest approach to the black hole it can be compressed and ignited. The resulting explosion will be very bright, like a supernovae, but looks different to a ...


4

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. The heat and energy of that burning constantly pushes on the matter inside the star holding it up. The fusing hydrogen generates enough energy to stop it from ...


3

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. (from http://www.oswego.edu/) Very boring in the grand scheme of things. Which is good for us :-)


2

Jupiter it is (moved from comment)


2

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 Chinese spoke of it (Crab nebula), and recorded their findings. If there was one, NASA couldn't hide it. You would know.


2

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


2

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 the mass of white dwarf as a whole, but that's because white dwarfs are almost entirely degenerate matter. Consider a 1.6 solar mass that is not a member of a ...


2

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 limit ($1.39 M_{\odot}$), it will undergo some sort of collapse. First, though, in response to Or has it already undergone supernova explosion? White dwarfs ...


2

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 explodes. Our Sun, like most other stars, just keeps fusing material at a slow and steady pace. It takes a different kind of star for the explosion to happen. ...


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