How many supernova explode every year?

badastronomy.beehiiv.com

367 points by rbanffy 8 days ago


rookderby - 4 days ago

First off, dont look at the outer wilds discussion on here, just play the game. Second - they didnt say how many letters we need to encode all of the observable supernova in a given year! So 100 billion galaxies, 1 per year per galaxy, we have around 1 billion to encode. Sorry two edits this moring, first one was right. due to math without coffee. 1e9/26^6 is about 3, 1e9/26^7 is less than one. So we might see 'SN2050aaaaaah'!

tialaramex - 5 days ago

That's one of my favourite hints in Outer Wilds. You will see a Supernova. Not with a fancy telescope, it's visible to the naked eye, and if you watch the sky you'll see another soon enough. You can see this right at the start, and unlike the random direction of the probe launch you don't need any game lore to, if you're smart enough, put two and two together.

kakuri - 4 days ago

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...

jxf - 4 days ago

I think this says less about supernovas and a lot more about how staggeringly, incomprehensibly vast the observable universe it.

ben_w - 4 days ago

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 environments giving the population-1/2/3 generations of stars…

dr_dshiv - 5 days ago

The most stars a person can see with the naked eye? About 8000.

And, less than half that, actually — since we can’t see the other side of the hemisphere

rwky - 4 days ago

This reminds me of a few years ago when I was doing my MSc our group was learning how to work one of the remote telescopes and we were asked to point it at the brightest object found by Gaia that week and it turned out to be a supernova. Very cool for your first observation using a remote telescope! If anyone wants to see it here it is https://ibb.co/Kzqbfq30

And here is the Gaia data http://gsaweb.ast.cam.ac.uk/alerts/alert/Gaia23bqb/

herendin2 - 5 days ago

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 supernovae). Thanks: yzydserd and zild3d

belter - 4 days ago

The SuperNova Early Warning System (SNEWS): https://snews2.org/

brings together the fantastic [1] Super-Kamiokande, the [2] IceCube, and other global detectors, to provide early warning of Supernovas.

You can subscribe... https://snews2.org//alert-signup/

[1] https://en.wikipedia.org/wiki/Super-Kamiokande

[2] https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory

thih9 - 5 days ago

> [Supernova discovery statistics for 2021] says there were 21,081 supernovae seen in 2021

> When the Vera Rubin survey telescope goes online, it’s expected to see hundreds of thousands of supernovae per year by itself.

drbig - 5 days ago

The universe is vast and full of nothing...

Which in case of explodey stars is a very good thing indeed!