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How many supernova explode every year?

badastronomy.beehiiv.com

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Re: How many supernova explode every year?

#161

Post by btilly »

ls612 wrote: post #156
ben_w wrote: post #74

Hmm… So that's cool, but now I'm thinking: the distant galaxies are redshifted and time-dilated in equal proportion, and also more densly packed because the universe was smaller in the past, so I expect the actual rate of supernovas to be significantly smaller than simply multiplying 1/century/galaxy by 1e11 galaxies. Edit: also I don't know if rate of supernovas changes over history thanks to different steller envir…

It probably isn't wildly lower today, we know of at least five or six big supernovae in the Milky Way in the past millennium. For 200B stars in our galaxy the size normalized rate implied by that would be like one ever 300 years. So if you extrapolated the Milky Way alone in (cosmological) modernity you would get 10/sec not 30/sec.

There is dust between us and most stars in the Milky Way that blocks them from view in visible light. Therefore we can only see a fraction of the supernovae in the Milky Way.

It is substantially easier for us to see supernovae in other galaxies that we're not facing edge-on. And we have a large sample size of such galaxies. That's why our best estimates of supernovae frequency are based on observations of such galaxies, and not on our observations of the Milky Way.

Re: How many supernova explode every year?

#162

Post by btilly »

crag-jene wrote: post #155
Someone wrote: post #26

Earlier quoted context omitted.

> If got the math right, then about 1 in every 32,000 stars in the universe goes supernova each year Can’t be right, can it? It would make the Sun (over 4 billion years old) an enormous outlier. It also would mean stars, on average, do not get very old. Over 10% of the stars that the ancient Greeks saw in the sky would have to have gone supernova since then.

Not all stars can go supernova. Sol will never go supernova. Only very massive stars can—or stars that become very massive by absorbing other stars.

Binary white dwarf systems can also go supernova, even if the combined mass is not that large as far as stars go.

Re: How many supernova explode every year?

#163

Post by Tuna-Fish »

yzydserd wrote: post #37
herendin2 wrote: post #18

If I got the math right, then about 1 in every 32,000 stars in the universe goes supernova each year. That's scary. But I think I'm getting the math very wrong. edit: I guess my error might be related to confusing a probability factor with the number of incidents in a period. edit: The right answer is probably up to 1 in every 10bn stars go supernovae in the universe each year (or 1 in 10bn die and a fraction are sup…

A star "lasts" about 10 billion years, so you'd expect about 1 in 10 billion stars to 'die' each year, but only a tiny proportion (the very largest) go supernova. Numbers are huge. Even tiny ratios mean something like 10-100 stars go supernova every single second somewhere in the universe. Sounds a lot? Only about 1 star per galaxy goes supernova per century. A lot of galaxies. Mindblowing.

> A star "lasts" about 10 billion years, so you'd expect about 1 in 10 billion stars to 'die' each year, but only a tiny proportion (the very largest) go supernova.

This analysis really doesn't work. Star lifespan is inversely correlated to size. A star large enough to just barely go supernova is only going to live for ~100M years, and as they get bigger, the lifespans fall rapidly.

(Why? Because gravity is what provides the pressure for fusion to happen, and so more gravity means fusion happens faster. For large stars, the luminosity is something like the mass to the 3.5th power. Also, convection works less well for larger stars, so as stars grow bigger, ever smaller proportion of the star takes any part in the fusion reactions in the core.)

Re: How many supernova explode every year?

#164

Post by aoeusnth1 »

darthrupert wrote: post #2

The whole things seems like such a massive living system that I cannot help guessing that what we think of as universe is just a somewhat large single creature.

Well, if physicalism is true then consciousness is a phenomenon of quantum fields, which span the universe. So yes, stretching the definition of creature, this could be interpreted as literally true.

Re: How many supernova explode every year?

#165

Post by citizenpaul »

kakuri wrote: post #132

I really feel like this article should also mention the rate of formation of new stars. According to [1] Universe Magazine the James Webb telescope has revealed that more than 3,000 stars are formed every second. [1] https://universemagazine.com/en/james-webb-comes-closer-to-r...

Based on this about 5.5 million stars are created every 30 minutes and only about 1 start goes supernova in the same period? This seems like it really reinforces the we are still in the early stages of the universe theory if the ratios are that imbalanced.

Still though the imbalance in those events makes me suspicious that we are missing something.

Re: How many supernova explode every year?

#166

Post by BobAliceInATree »

citizenpaul wrote: post #165
kakuri wrote: post #132

I really feel like this article should also mention the rate of formation of new stars. According to [1] Universe Magazine the James Webb telescope has revealed that more than 3,000 stars are formed every second. [1] https://universemagazine.com/en/james-webb-comes-closer-to-r...

Based on this about 5.5 million stars are created every 30 minutes and only about 1 start goes supernova in the same period? This seems like it really reinforces the we are still in the early stages of the universe theory if the ratios are that imbalanced. Still though the imbalance in those events makes me suspicious that we are missing something.

The vast majority of stars don't supernova.

Also, we're at the tail end of star-forming era. about 95% of all the stars that will be formed, have already been formed.

https://www.scientificamerican.com/blog/life-unbounded/the-s...

Re: How many supernova explode every year?

#167

Post by Trixter »

spookie wrote: post #142
frabert wrote: post #135

Earlier quoted context omitted.

The thing about Outer Wilds for me is that it's a game about exploration, but most attempts at exploration are punished (limited time frame, sands suffocating you, "ghost matter" kills...). They stuck with a "hard scifi" control scheme where you control your character in 6dof with inertia, which makes some things unnecessarily hard and did not (IMO) add anything to the game itself. The things you interact with in the…

Did you play with a controller by chance? Asking because I prefer first person view games on PC

I did not play with a controller, which made Dark Bramble effectively impossible to finish because the keyboard is all-or-nothing thrust. Had to cheat to get past it. They should have said that using a controller was mandatory, not recommended.

Re: How many supernova explode every year?

#168

Post by loloquwowndueo »

h4ck_th3_pl4n3t wrote: post #45
loloquwowndueo wrote: post #43

Earlier quoted context omitted.

We don’t need to fix that, do we? Just let it be. You’ll be long dead anyway.

> We don’t need to fix that, do we? Just let it be. You’ll be long dead anyway. Spotted the republican

Who, the guy I replied to who expects to be around in a trillion years and wants to live forever? Yeah, peak republican right there.

Re: How many supernova explode every year?

#169

Post by rbanffy »

packetlost wrote: post #123
criddell wrote: post #120

Earlier quoted context omitted.

I bought Outer Wilds based on recommendations like yours and I found it kind of boring. The world is mostly empty and the repetitiveness wore me down. I didn't finish it. It's a great looking game though and the first hour or two I had a blast.

Same here. I found the controls to be frustrating and the game-play loop to be kinda dull. The story on the other hand, is very good. I get that the game-play is meant to illicit certain feelings, but it just didn't do it for me. I did enjoy reading a synopsis of the story on the wiki though.

> The story on the other hand, is very good.

There seems to be lots of games that should have been movies or series instead.

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