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glen chapman
2004-Nov-11, 09:03 AM
Anyone suggest a good site for info on the theory around nova and what causes them. Been googling, but suprised at the lack of useful hits.

Finally aside from white dwarfs gobbling mass from parent stars are there any other half decent theories doing the rounds

Thanks in advance

Normandy6644
2004-Nov-11, 03:17 PM
Are you talking about a nova or a supernova? Your wry description is the current theory on how Type Ia supernovae happen, much different from a nova, which is just an increase in brightness of a star, as opposed to actually exploding.

Hamlet
2004-Nov-11, 04:19 PM
If you're looking for supernova information this site has a good section on the Lives and Deaths of Stars (http://www.astronomynotes.com/evolutn/s1.htm).

This NASA (http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_contents.html) site it pretty good too.

Here (http://rsd-www.nrl.navy.mil/7212/montes/sne.html) is link to a page of other links about supernovae.

This (http://grumpy.as.arizona.edu/~gschwarz/main/node2.html) site has some info on just novae, but some of the navigation links are broken.

Some more novae info here (http://www.aavso.org/vstar/vsots/0501.shtml).

That's about all I have. I hope it helps.

Bob
2004-Nov-11, 04:51 PM
There was an interesting article about supernovas in yesterday's NY Times.

http://www.nytimes.com/2004/11/09/science/space/09supe.html?oref=login

Did you know that the region in a supernova where carbon and oxygen are fused into heavier elements is only as thick as a piece of paper? I didn't, but some astronomers with a supercomputer think that might be true.

Eroica
2004-Nov-11, 05:31 PM
Are you talking about a nova or a supernova? Your wry description is the current theory on how Type Ia supernovae happen, much different from a nova, which is just an increase in brightness of a star, as opposed to actually exploding.
Sounds quite like a nova (http://en.wikipedia.org/wiki/Nova) to me. :wink:

Normandy6644
2004-Nov-11, 08:23 PM
Are you talking about a nova or a supernova? Your wry description is the current theory on how Type Ia supernovae happen, much different from a nova, which is just an increase in brightness of a star, as opposed to actually exploding.
Sounds quite like a nova (http://en.wikipedia.org/wiki/Nova) to me. :wink:

You get the idea! :D

glen chapman
2004-Nov-15, 11:23 PM
No I definately mean a nova. Not a supernova - I have a fair understanding of how white dwarfs go supernova after exceeding the Chandra limit.

I am looking for any theories that might suggest other ways stars can go nova. I dont mind if they are a little half baked as long as they kinda sound plausable.

Glen

Evan
2004-Nov-15, 11:36 PM
Shoot one with the Illudium Q-36 Explosive Space Modulator.

pghnative
2004-Nov-16, 01:47 PM
There was supposed to be a "KA-BOOM" --- where was the "KA-BOOM"!!

Spaceman Spiff
2004-Nov-16, 02:43 PM
No I definately mean a nova. Not a supernova - I have a fair understanding of how white dwarfs go supernova after exceeding the Chandra limit.

I am looking for any theories that might suggest other ways stars can go nova. I dont mind if they are a little half baked as long as they kinda sound plausable.

Glen

The Wikipedia description posted by Eroica is spot on. Note that this description of a nova is not the same thing as a type 1a supernova. The mechanisms, although both involve binary systems with mass transfer to a white dwarf, differ.

Madcat
2004-Nov-16, 05:00 PM
If you're trying to plausibly blow up a star for fictional purposes, I have little to give you but my best wishes. Those things have mass. It's gonna take a lot of energy to do something that anyone would notice.

Evan
2004-Nov-16, 06:05 PM
OK, let's make something up.

A space war is underway. The bad guys have the upper hand. They have found that drifting in interstellar space are occasional dark objects that are made from anti-nickle/iron. By directing a stream of normal matter (big machine gun?) at one of these objects which masses gigatons, it creates extreme thrust [1]. They are able to accelerate it towards the primary star of the system in question. Some time later (years ?) the object drifts in on a hyperbolic orbit and plunges into the star. The energy release from 100% conversion of matter to energy destroys the star.

[1] Don't try this at home and stand well back.


PS: That should be sufficiently under-cooked...

Note: The estimated matter to energy conversion rate of Sol is 4.26 million tonnes per second. So, dumping in several gigatons of antimatter ought to have a significant effect

snowcelt
2004-Nov-16, 06:15 PM
The abundance (or the lack) of minerals in the range of less that Fe, let us say the mass number of forty, is easy. Nuclear synthisis within stars have paths which work better than others. Thermal Conduction adds to a basic synthisis in that small gradients, that, where electrons form a degenerate gas, create a situation were energy can not escape. Opps! That is an energy disipation basic law. Low, overall, poorly represented elements, are a characteristic of secondary stellar reactions---where all of the final energy is manifested. There is no such thing as a Carbon+Carbon+Carbon reaction to create whatever the heck element 36 is. Could be, if such a thing could happen, that lesser elements would occur.

However, reguardless of my attempt, the pausity of certain elements mean there is no reason that they do not fit. Reason ties what we know, what we observe, together.

glen chapman
2004-Nov-16, 10:54 PM
Okay we are jumping all over the place here with assumptions. Yes I am writing a story. However rather than blow up a star I am trying to create a situation where an astrophysist on an expedition to a star realises something is not right.

IE the internal dynamics of the star dont fit what he is observing on the surface. He realises the natural evolution of the star is being retarded.

The natural choice would be variable stars, however the thermo-dynamics of such stars are not well enough understood for me to tinker with possible extrapolations that an astrophysicist could reasonably make.

Standard nova are out. I really dont want a binary system, will cause more problems than it will fix. So was looking for other mechanisms that might work for me.

The only other thing I have to work with are cepheid variables. Seems their cycle can be directly linked to their spectral class.

So as you can see I am trying to be a little subtle, while writing a piece that is accurate enough to pass muster with the Bad Astronomer.

Thanks Glen

eburacum45
2004-Nov-17, 08:46 AM
How about a Helium flash?
http://www.daviddarling.info/encyclopedia/H/helium_flash.html
or a superflare as seen at Kappa Ceti
http://www.solstation.com/stars/kap-ceti.htm
?

Harvestar
2004-Nov-17, 02:16 PM
There was an interesting article about supernovas in yesterday's NY Times.

http://www.nytimes.com/2004/11/09/science/space/09supe.html?oref=login

Did you know that the region in a supernova where carbon and oxygen are fused into heavier elements is only as thick as a piece of paper? I didn't, but some astronomers with a supercomputer think that might be true.

I do like getting to the end of an article and finding quotes from a member of my prelim committee (and my boyfriend's advisor). ;) :)