What conditions cause a star to do one or the other?

Mass. Our Sun is far below the threshold to do either. It's destined to swell to a red giant and eventually blow off its outer layers to end looking rather like this:

We wont be around when the star does that either way, I am more worried about an orange hole right now.

(January 16, 2017 at 8:35 am)Rhondazvous Wrote: What conditions cause a star to do one or the other?

Mass, in essence if a star has sufficient mass it will eventually undergo a core collapse resulting a singularity and creating a black hole. We have observed Magnetars 40X the mass of the Sun, therefore in order to produce a black hole a star must be larger than 40X the mass of the Sun.

As a star like the Sun uses it's fuel of Hydrogen it will eventually run out and start fusing heavier elements in sequence;
Helium, Lithium, Beryllium etc. during which it loses control of it's outer layers which expand becoming a Red Giant enveloping the inner planets. When it reaches the point that it has to fuse Iron the reaction absorbs energy instead of releasing it, the outer layers cool and collapse into the core, this triggers an Implosion better known as a Super Nova destroying the star and any planets orbiting and with a star the size of the Sun leaving a White Dwarf with an expanding planetary nebula.

I'd prefer a Shelby Cobra but will settle for a Nova.

iirc neither, it's too light. It will get bloatet, violently shed some outer hulls and settle to a white dwarf. It won't classify as a supernova, and it can't produce a nova.

Re your question: the star mainly needs to be heavy enough to trigger a supernova explosion, but supernovas don't yield white dwarfs, but instead compresses the core to an even denser neutron star, or if the mass is even higher, to a black hole. Or nothing of the star remains at all...

(January 16, 2017 at 9:12 am)mh.brewer Wrote: I'd prefer a Shelby Cobra but will settle for a Nova.

Of course you would value an impractical gas hog that pollutes and you cant legally speed in anyway.

Damn glad you had nothing to do with the space race that got us to the moon. The Apollo 13 guys would have died because of selfish narcissism "what's you're problem, I got away with it once, what could ever go wrong?" 

I am all for the free market, just not an impractical market. Your moronic attitude is why it took so long to get led out of gas, why it took so long to mandate seat belts and air bags. 

You have the same mentality short term thinking as a drunk driver. You make it home several times thinking you'll never have an accident. 

We also don't have rotary phones anymore. It won't kill you to think of others or the long term affects of what we do as humans. Just because you can do something doesn't mean it is always good.

Apparently 'no va' is Spanish for "won't go".

(January 16, 2017 at 10:07 am)Brian37 Wrote:

(January 16, 2017 at 9:12 am)mh.brewer Wrote: I'd prefer a Shelby Cobra but will settle for a Nova.

Of course you would value an impractical gas hog that pollutes and you cant legally speed in anyway.

Damn glad you had nothing to do with the space race that got us to the moon. The Apollo 13 guys would have died because of selfish narcissism "what's you're problem, I got away with it once, what could ever go wrong?" 

I am all for the free market, just not an impractical market. Your moronic attitude is why it took so long to get led out of gas, why it took so long to mandate seat belts and air bags. 

You have the same mentality short term thinking as a drunk driver. You make it home several times thinking you'll never have an accident. 

We also don't have rotary phones anymore. It won't kill you to think of others or the long term affects of what we do as humans. Just because you can do something doesn't mean it is always good.

Wow, thanks Brian. What insight. I'm a changed man. 

Shelby left behind for a Camero.