Presumably the resulting nebula could end up the same apparent size as the moon..... After it's had millions of years to expand, and for the moon to retreat even more from the Earth...No, that's not how this works. To be the size of the full Moon at that distance, the actual explosion area would have to be not massive, but absurdly ludicrously humongous. No, it will be brighter than a full Moon, yes, larger or large as, not.
The explosion area of a supernova just some 600LY away will appear to be absolutely humongous, because it will be for a star this massiveNo, that's not how this works. To be the size of the full Moon at that distance, the actual explosion area would have to be not massive, but absurdly ludicrously humongous. No, it will be brighter than a full Moon, yes, larger or large as, not.
Surely outer layers that will be thrown off by the collapse of the core should be visible from this close.No, that's not how this works, that's not how any of this works ...a supernova won't instantly become an object some light years in diameters against any possible law of nature, just because is a very very big explosion. Current Betelgeuse diameter is loosely estimated at something between the size of Mars and Jupiter's orbit. Not Jupiter, Jupiter's orbit. When it'll go nova, the bulk of the star mass will collapse again before rebounce, the actual release of energy in the optical spectrum will happen when the star will be a lot smaller than it currently is. And currently, it can be barely resolved as nothing more than a bunch of pixels by the most advanced instruments humanity has been able to devise until now.
Magnitude and angular diameter are related, but not necessarily proportionally.
No, that's not how this works, that's not how any of this works ...a supernova won't instantly become an object some light years in diameters against any possible law of nature, just because is a very very big explosion. Current Betelgeuse diameter is loosely estimated at something between the size of Mars and Jupiter's orbit. Not Jupiter, Jupiter's orbit. When it'll go nova, the bulk of the star mass will collapse again before rebounce, the actual release of energy in the optical spectrum will happen when the star will be a lot smaller than it currently is. And currently, it can be barely resolved as nothing more than a bunch of pixels by the most advanced instruments humanity has been able to devise until now.
Magnitude and angular diameter are related, but not necessarily proportionally.
All seems right. I just don't know if gas just keep expanding at the same rate. Only because gas has initially such high velocity doesn't mean it keeps it. It probably decelerates as some gravitational pull from the star's remnant is still applied. Or it could be negligible. Obviously just a forum speculator hereJust take a look at Barnard's Loop. It is believed to have been created approximately 2 million years ago. It is approximately 600 arcminutes in the sky. This is a measure of it's size. The moon is 31 arcminutes in size. This means the moon is about 20 times smaller than Barnard's Loop. That means that in 1/20th of 2 million years it was the size of the Moon. Therefore, ( 2,000,000 / 20 = ) 100,000 years is how long it took to become Moon sized. Betelgeuse is about half the distance, so... roughing the math again, 50,000 years before (if) it's nebula reaches that same size.
Anyone feel free to correct me if I got that wrong, not an expert here, but that's how I understand it.
No, it would actually be about the size of the moon in the night sky.
We're getting there, hold on I can manipula...err, adjust my calculations slightly.Betegeuse is 700 light years away. To be the apparent size of the moon in the sky (an angular diameter of about half a degree) , it would need to be 6 light years across.
All seems right. I just don't know if gas just keep expanding at the same rate. Only because gas has initially such high velocity doesn't mean it keeps it. It probably decelerates as some gravitational pull from the star's remnant is still applied. Or it could be negligible. Obviously just a forum speculator here
Rest assured, that if it goes supernova, you'll find me glued to my old Schmidt–Cassegrain telescope. I'd miss Betelgeuse, but having the chance to see it would probably beat anything else, including reproduction.Betegeuse is 700 light years away. To be the apparent size of the moon in the sky (an angular diameter of about half a degree) , it would need to be 6 light years across.
That stuff is interesting, but too far away I'm hoping for a mini little black hole in place of Betelguese, although not highly likely from what I understand. It would have to retain like half of it's mass in the core when it goes boom to collapse back to black hole. Otherwise it'll just be another boring neutron star.The thing that will happen will probably be more interesting than that. We'll see an expanding cloud of gas/debris, but it won't just be the matter actually expanding away from the explosion. The first thing we'll see will be the matter already being ejected over the years/centuries/eras, progressively illuminated by the "photon wave" of light from the explosion, as it progressively travels away at the speed of light. Since that light will bounce and be reflected by matter along the way, we'll also see the light coming from that matter, and arriving at different times, potentially giving the impression of a shockwave traveling faster than the speed of light. Of course matter will stil be expanding at the same time at a slower speed and still emitting its own/reflected light, so TL;DR, we'll see funny stuff for centuries to come.
To see funny stuff like that already happening in real time, google "V838 Monocerotis light echo".
Perhaps we already have a black hole much closer than Betelgeuse:That stuff is interesting, but too far away I'm hoping for a mini little black hole in place of Betelguese, although not highly likely from what I understand. It would have to retain like half of it's mass in the core when it goes boom to collapse back to black hole. Otherwise it'll just be another boring neutron star.
It's too interesting to be true Probably just some rogue planet passing by, or it got captured and decided to hang around.Perhaps we already have a black hole much closer than Betelgeuse:
Planet Nine may be a black hole the size of a baseball
A slew of oddly orbiting objects indicates a massive planet is hiding in the outer solar system. But one group of astronomers says it might be a tiny black hole instead.astronomy.com
It's an interesting hypothesis. I haven't followed the Planet Nine thing, not having had access to a telescope for years, but if amateur astronomers are able to find exo planets, and astronomers back in 1847 could calculate the position of Neptune based on the not completed orbit of Uranus, it can't be impossible to find a tiny black hole in our own solar system.