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54 votes
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Why is there a gap in this image of supernova discoveries?

The coordinate system in this image is RA and Dec. It is a coordinate system which uses the Earth's equator (projected onto the sky) as its midline. The inverted U is the Milky Way. The Milky Way is ...
James K's user avatar
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45 votes

Are we really star-stuff from the interior of collapsing stars?

The straightforward answer is, "Yes, we are made of star stuff." Some of it will be from the interior of collapsing stars, some will be from supernovas, some from normal everyday fusion, and some ...
Rory Alsop's user avatar
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45 votes
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When stars explode after running out of fuel, why are new stars born from the remnants?

New stars are not formed from the nebulae created when a parent star explodes. In space there is thin interstellar gas and plasma. This gas is buffeted and blown by the solar winds of stars, and the ...
James K's user avatar
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43 votes
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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 ...
Peter Erwin's user avatar
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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.
Hartmut Braun's user avatar
39 votes
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What would happen if someone had a telescope and watched Betelgeuse when it goes supernova?

No, it would not be a problem. Supernovae are not at all like flashbulbs – they brighten over a period of many days and dim again even more slowly. Here are a number of different light curves taken ...
Mark Olson's user avatar
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37 votes
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When was it worked out/discovered that our Sun can't go supernova?

I think the definitive work is that of Hoyle & Fowler (1960). They argued that supernovae were produced by two possible mechanisms - what they called an implosion/explosion or an explosion within ...
ProfRob's user avatar
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35 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 ...
JohnHoltz's user avatar
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35 votes
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How can many stars be formed from the remains of one supernova?

Stars don't "come from" a supernova. Stars come from the interstellar gas in the galaxy, particularly where it is more concentrated into nebulae. This gas is mostly hydrogen and helium, but ...
James K's user avatar
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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 ...
ProfRob's user avatar
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32 votes

What observations can be expected on LIGO if any when Betelgeuse goes supernova?

Potentially, a short (less than a second) burst of gravitational waves (GWs) would be detected. Much depends on asymmetries in the core collapse, since a spherically symmetric collapse would not ...
ProfRob's user avatar
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32 votes
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What would happen if a small black hole fell into a star?

How much matter can a small black hole absorb? This determines the answer to your questions. A simple approximation is that moving black holes absorb everything they pass through out to a radius $kR_S$...
Anders Sandberg's user avatar
31 votes
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How often do Type Ia supernovae occur?

There is a lot of scope to provide a very detailed answer here. The rate depends on what sort of a galaxy you are considering and when, what its star formation rate is (or was) and what its total ...
ProfRob's user avatar
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29 votes

Why don’t supergiants at least start to fuse nickel into even heavier elements before going supernova?

The final stages of nucleosynthesis are a statistical equilibrium process. At the same time as nuclei are being built up, photodisintegration is breaking them down. The temperatures required to ...
ProfRob's user avatar
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29 votes
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Why are there so few supernovae in M31 (Andromeda)?

The low supernova rate in M31 can be directly attributed to the fact that the galaxy's star formation rate is much lower than the Milky Way's. Andromeda is currently in a relatively quiet phase in ...
HDE 226868's user avatar
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27 votes
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What causes fast moving pulsars to move so fast?

The most likely scenario is that an asymmetry in the supernova explosion imparts momentum to the proto neutron star at its core. The issue is not settled. A recent study by Verbunt et al. (2017) ...
ProfRob's user avatar
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25 votes

What would happen if someone had a telescope and watched Betelgeuse when it goes supernova?

If you insist on observing the exploding Betelgeuse at peak brightness, you could potentially damage your eye. The complete answer enters the realm of physiology. Here I'll discuss the astronomical ...
pela's user avatar
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23 votes

When stars explode after running out of fuel, why are new stars born from the remnants?

New stars aren't directly born in the exploded remnants of massive stars. Star formation does not occur in newly produced supernova remnants. Instead what happens is that, over the course of millions ...
ProfRob's user avatar
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23 votes
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Could it be possible to detect planets from stars that went supernova through the resulting nebula shape?

The escape speed of a big planet like Jupiter is about 60 km/s. The speed of the ejecta from a supernova explosion is something like $10^4$ km/s. i.e. Jupiter would have little discernable ...
ProfRob's user avatar
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21 votes
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Are stars expected to become dimmer before a supernova?

The connection between the dimming and a putative supernova relies on the interpretation that the decrease in luminosity may be due to circumstellar material, ejected in the years/decades/centuries ...
HDE 226868's user avatar
  • 36.6k
20 votes

Are we really star-stuff from the interior of collapsing stars?

Sagan's quote is half-correct. While some of these elements are created during or immediately prior to a supernova of some sort, others are either partially or entirely fused during normal stellar ...
HDE 226868's user avatar
  • 36.6k
20 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 ...
ProfRob's user avatar
  • 153k
20 votes

Where did the hydrogen come from in a type II supernova?

Good question - the answer is that stars are not in general well mixed - or rather, the nuclear-burning core is not well-mixed with the rest of the star. That means that a star will finish hydrogen ...
ProfRob's user avatar
  • 153k
20 votes

How can we know if a star which is visible in our night sky goes supernova?

It is not possible to know. The speed of light is the speed of information. The information "the star has exploded" cannot travel faster than the speed of light, so there is no way to know ...
James K's user avatar
  • 123k
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 ...
ProfRob's user avatar
  • 153k
19 votes

How can many stars be formed from the remains of one supernova?

The mean mass of a star in a typical star forming region is about 0.3 solar masses and contains about 1% by mass of elements heavier than helium A typical core-collapse supernova progenitor might have ...
ProfRob's user avatar
  • 153k
18 votes

Is there a possibility that a white dwarf can turn into a neutron star or a black hole?

The answer is: to a neutron star - possibly; to a black hole, no. The process whereby a neutron star is formed is known as an accretion induced collapse and is being seriously debated, especially in ...
ProfRob's user avatar
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18 votes
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Is oxygen an alpha element?

Two things. The abundance of oxygen is a difficult thing to measure in optical spectra - much harder than Mg, Ca, and Si. So these latter are usually used to represent "the alpha elements". ...
ProfRob's user avatar
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18 votes
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Metallicity in gravitational wave astronomy

As you say, metallicity in this context refers to the proportion of the interstellar medium a star forms from that consists of elements heavier than helium. It can be expressed as a (mass) fraction (...
ProfRob's user avatar
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17 votes
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Will Sirius B start accreting from A and become a supernova type Ia?

Will Sirius B start accreting? Yes, it is doing so now. Sirius A will have a wind and some of that wind will be captured by the white dwarf. The effectiveness of wind capture is a strong function of ...
ProfRob's user avatar
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