# Thread: maximum magnitude of supernova Ia slightly modified

1. Newbie
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## maximum magnitude of supernova Ia slightly modified

hej hej, this is my first time post:

is there an equation for the maximum magnitude of supernova Ia? I’ve only seen empirical evidence for the –19.8 intensity. I assume such an equation would be based on the mass of white dwarf when it reaches the Chandrasekhar limit around 1.4 M.

whether or not there is such an equation is not my real question. What I really want to know is the maximum magnitude of a supernova Ia if every thing is the same except the total number of atoms where 1/20 of what we think it is. That is, lets pretend that the white dwarf’s atoms are some how 20 times heavier and hence we need a lot less to reach the Chandrasekhar limit.

I know it might seem silly to pretend that the white dwarf is smaller and made up of heavier [but otherwise normal] particles, but please see past this point for now.

I assume that such a magical mini supernova Ia will have a dimmer maximum magnitude I just want to find out how much dimmer.

2. nearc I have approved your post and moved it to the Question and Answers section. Trying to see past this post, if you are contemplating an ATM theory and are gathering information before proposing it, please read the rules concerning ATM posts.

3. Originally Posted by nearc
What I really want to know is the maximum magnitude of a supernova Ia if every thing is the same except the total number of atoms where 1/20 of what we think it is. That is, lets pretend that the white dwarf’s atoms are some how 20 times heavier and hence we need a lot less to reach the Chandrasekhar limit.

I know it might seem silly to pretend that the white dwarf is smaller and made up of heavier [but otherwise normal] particles, but please see past this point for now.
Method 1: the light of a SN Ia is due in large part to the radioactive decay of Ni-56 atoms created in the explosion. If there are 20 times fewer atoms, perhaps there would be 20 times fewer Ni-56 atoms, and hence the explosion would be 20 times dimmer.

Method 2: since you are postulating the existence of particles which are unlike any we have seen -- "heavier but otherwise normal particles" -- you may as well postulate their behavior, too. Just make up a number that will fit your ideas.

4. Newbie
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## equation?

so there is no equation for the maximum magnitude of supernova Ia?

and please if you don't have an answer i would appreciate not getting another negative response. however, it would be nice to see something like “hey welcome to bad astronomy…”

5. Originally Posted by nearc
... it would be nice to see something like “hey welcome to bad astronomy…”

6. Originally Posted by Roobydo
Thanks Roobydo!

Technically this isn't Bad Astronomy, which is now a blog, this is BAUT and we're proud of it. So, welcome to BAUT, nearc

7. Order of Kilopi
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Originally Posted by nearc
so there is no equation for the maximum magnitude of supernova Ia?

and please if you don't have an answer i would appreciate not getting another negative response. however, it would be nice to see something like “hey welcome to bad astronomy…”
Equation writing here is a bit of a pain in the backside. Considering that the equation you are looking for is extremely complex, trying to copy it would not be worth the effort. Any decent astrophysics text should give you the information you seek.

Sort of.

The question you ask is not a simple one. Current theory of SNIa are not that it is a failure of electron degeneracy that causes the SN, but runaway carbon burning at a mass slightly lower than the Chandrasekar limit. Upping the atomic mass of the particles from carbon-oxygen to around iron would change the cause to degeneracy failure. This would greatly change the light curve associated with the SN. Then, like Stupendous Man said, most of the light comes from the decay of Ni-56, but you would have a completely different chemistry due to starting out with elements around the mass Ni in the first place.

Then you would need to know wether the star was completely destroyed by the explosion. I have no clue about this one, since I dont really know the details of the explosion.

If I were to WAG, I would say a more rapid rise to max brightness, then a more rapid dimming afterward, with max brightness being a bit brighter than standard.

If you really want a more detailed description, you are unlikely to get it here. The question you ask is one that would take graduate students weeks to figure, which is a bit much for most of us here.