Counting Supernovae: Estimating the Frequency of Stellar Explosions

[wolram]

http://www.supernovae.net/isn.htm

this link gives a listing of supernova discoveries.
i am atempting to build a picture of the evolution
of the universe ,ie how many stars go supernova,
how many pulsars are formed, how many stars are
formed etc, etc.
can anyone give me some numbers?
estimates, guesses?

 

[wolram]

approx 252 supernova detected in 2003?

 

[Nereid]

CBAT

The IAU's CBAT (Central Bureau for Astronomical Telegrams) has a page dedicated to supernovae:
http://cfa-www.harvard.edu/iau/lists/OtherLists.html
You could subscribe to the circulars, and compile the data for yourself as it comes in. You will find that pretty much every supernova which is detected gets reported here, although sometimes there's a delay between discovery and reporting.

Be careful with how you analyse the data; there are very strong selection effects re detecting supernovae, e.g. dedicated searches, completeness of sky coverage (esp southern vs northern hemisphere; winter vs summer), depth, etc.

 

[wolram]

thankyou for the information nereid.

however i am not looking for definitive information
my aim is to have a basic picture for the evolving
universe, i have searched the net for data with
no results for,

! new star discoveries
2 black hole discoveries

a "snap shot" of stars,supernovas,blackholes, etc discovered in some time period.
2---, 2003 would give an overview of how the universe is
evolving.

 

[Nereid]

If you download the CBAT file, you'll have data on (nearly) EVERY observed supernova for over 100 years.

Zwicky did the landmark research, in the 1950s IIRC, on how often you can expect to see a supernova in an average galaxy; the estimate was once every 30 to 300 years (IIRC). More recent work may have refined this estimate.

 

[Labguy]

Originally posted by Nereid
The IAU's CBAT (Central Bureau for Astronomical Telegrams) has a page dedicated to supernovae:
http://cfa-www.harvard.edu/iau/lists/OtherLists.html
You could subscribe to the circulars, and compile the data for yourself as it comes in. You will find that pretty much every supernova which is detected gets reported here, although sometimes there's a delay between discovery and reporting.

Be careful with how you analyse the data; there are very strong selection effects re detecting supernovae, e.g. dedicated searches, completeness of sky coverage (esp southern vs northern hemisphere; winter vs summer), depth, etc.

Great site, I saved it in my "favorites" stellar evolution folder (the supernova list part). The other links from there are very handy too. I need to get more current on the latest info/theories. Seven months of bedridden illness kept me away for awhile.

If you, or any other reader, has links to "most recent" sites, I would appreciate having them by private message. I have about 400 sites in 50 folders bookmarked, but some should probably be deleted and replaced.

Labguy

 

[selfAdjoint]

Neried,

Zwicky did the landmark research, in the 1950s IIRC, on how often you can expect to see a supernova in an average galaxy; the estimate was once every 30 to 300 years (IIRC). More recent work may have refined this estimate

I am trying to work out the probablility of the original cloud of the solar system encountering a supernova or its recent remains during its evolution. evidently it did, with important consequences for life. Superficially similar clouds that did not would be severely lacking in key 2nd and 3d row elements like oxygen, carbon, phosphorus, etc.

Are you aware of any work on this? If we approximate Zwicky's rate as ~ 10^-2 per year, then that's 10^6 per 10^8y, my ignorant estimate of the window of opportunity for the cloud. That's in a whole galaxy, but our cloud would only traverse a tiny fraction of a galaxy in that time. Say 10^-8 ? Based on the idea that there are 10^8 stars in our galaxy and pretending they are uniformly distributed... So the probability comes out to 10^-2 again, since the 100 millions cancel out. One evolving presolar cloud in a hundred gets blessed with the vital elements. Not enough to rule out other life in our galaxy, but should be a factor in any Drake type calculation.

Where I'm coming from. The simplest, least special pleading answer to Fermi's question "Where are they?" is "There aren't any." So I'm looking at factors that could prevent other stars from having life bearing planets. The other factor I've thought of is a moon big enough to raise tides^*. We;re the only planet in the solar system that has one. What are the general odds?


^*Originally suggested by John W. Campbell Jr. in an editorial in Analog.

 

[Nereid]

This question is one I'm interested in too.

I've seen quite a few articles which address the question, at least tangentially; I'll see what I can dig up.

It would also be a great idea to see what we can work out for ourselves. Here are some ideas:
- there are several different types of supernovae (SN), and several paths to an SN explosion. Those which result from the core collapse of a 'pure' (no significant interactions with other stars in its history) heavy star cannot have gone far from their birthplace, which would most likely have been a decent-sized star cluster. How often would the solar system have come close to such a cluster?
- supernovae leave pretty tell-tale remains, which are quite distinctive for thousands (millions?) of years. What does the local distribution of SNRs and pulsars tell us? From their observed motions, what can we extrapolate?

The binary planet idea is also worth some attention, though data to do tests are scarcer.

(more later)

 

[wolram]

http://spaceflightnow.com/news/n0309/18supernovae/



Those explosions spewed elements like carbon, oxygen and iron into the void at tremendous speeds. New simulations by astrophysicists Volker Bromm (Harvard-Smithsonian Center for Astrophysics), Naoki Yoshida (National Astronomical Observatory of Japan) and Lars Hernquist (CfA) show that the first, "greatest generation" of stars spread incredible amounts of such heavy elements across thousands of light-years of space, thereby seeding the cosmos with the stuff of life.

 

[Nereid]

spherical turkeys (a.k.a. SNe)

Using the same sized envelope as I did for my posts on the expanding Earth idea thread ...
-> Assume a SN can occur anywhere at random in the Milky Way disk (which starts, let's say, 1,000 ly from the centre, and ends 50,000 ly out).
-> Assume the disk is flat.
-> Assume the Earth would be in for a nasty experience if there were an SN within 10 ly.
-> Assume the average rate of disk SNs is 1 per 100 years.

My small envelope says we could expect a nasty experience every ~2.5 billion years.

With a year's worth of old envelopes (well, maybe a week's if you include all the junk mail ), we could refine this by a factor of 10 to 30 IMHO.

Maybe I'll apply the secret Nereid approach for making WAGs (it's actually very powerful, for reasons I don't fully understand), and calculate a range.

 

[wolram]

my math skills are non existent but i have attempted
the calculation, result
2,500,267,528 yrs "leaving out all numbers to the right
of decimal point"

what is a WAG?

 

[Nereid]

WAG?

I believe those folk familiar with the "American" variant of the English language could provide a more colourful insight, but "wild a*se guess"

 

[wolram]

shock horror, scientists "guess"

it took me an hour to work out that problem, now i
find out you WAG them

 

[Nereid]

LOL!
The Nereid secret is an approach that I've used in many different fields of endeavour. It's quite spooky in how well it works; by that I mean when I (or others) put in a lot more time and effort and come up with a better estimate (in the sense of 'taking account of more factors', and 'being more methodical and careful', etc), that estimate is well within the estimated range determined from the 'Nereid secret approach', almost always. I call it a WAG because, a priori, it seems too simplistic. A colleague once told me that the approach does have a good basis, so I shouldn't be so surprised at how good the estimates it produces end up being.

Do you use XL? or just pencil and paper?

 

[wolram]

i spent half hour looking for kwaculator only to find
u/s, so i had to use ancient method and re activate
long unused brain cells, i wish i had a WAG.