What if...

[Vegeta (Ibrahim)]

Hi, I have a stupid question that i've been thinking about for a while. My question is:
What would happen if you were observing a red giant star such as betelguese, Antares or eta carina, and the star suddenly went nova in the eyepiece?

[Astro_Bot]

Originally Posted by Vegeta

Hi, I have a stupid question that i've been thinking about for a while. My question is:
What would happen if you were observing a red giant star such as betelguese, Antares or eta carina, and the star suddenly went nova in the eyepiece?

You might get invited to appear on a morning show? Or maybe endorse some astro product? If that happens to you, buy a lottery ticket!

I think the brightness increase to its peak takes days. AFAIK, novae/supernovae are usually detected by comparison of before and after images.

[Vegeta (Ibrahim)]

Thanks for the reply, I always thought the sudden increase in brightness and radiation output would cause damage.

[JB80 (Jarrod)]

I doubt there would be any permanent damage although I'm not certain about that but I guess it would be a bit of a shock and natural reflexes would probably turn you away straight off. From there on you wouldn't need anything to help you see it.

A good little explaination of Betelguese' peak luminosity can be found here...http://space.about.com/b/2011/01/24/...va-in-2012.htm

Typically Type II supernova (a supernova resulting from the collapse of a massive star) of this size have a peak luminosity (integrated over all wavelengths) approaching about 1 billion times the power of our Sun.

Because the apparent luminosity (effectively the amount of energy that arrives at Earth per second) falls off with the square of the distance. In Laymen's terms, if our Sun were ten times further away from us, its apparent luminosity would be 100 times less.

So given the 600 light-year distance to Betelgeuse (about 40 million times further away from us than our Sun), the apparent peak luminosity of the supernova explosion will be roughly 0.00006% of our Sun's apparent luminosity. Clearly that is such a small percentage that the additional flux will have zero effect on our planet.
What is perhaps more interesting is the optical peak brightness (how it will appear to the naked eye). It should appear noticeably brighter than Venus on a clear night, perhaps significantly so. (I've seen reports that would indicate the brightness might rival that of the full moon, but I am somewhat skeptical of this; the numbers just don't seem to add up in my estimation.) Short story is that it will be noticeable even to those without scientific training.

The same would be said for any particles reaches us, I think?

[Blue Skies (Jacquie)]

Originally Posted by Vegeta

Thanks for the reply, I always thought the sudden increase in brightness and radiation output would cause damage.

I think you've fallen for the movie effect - nova and supernova don't go "pop!" in a flash, then vanish in seconds. They gradually increase in brightness over hours, if not days. Same with fading once its peaked. You can't have that happen in a movie, so they tend to speed it up. Any astronomy gets sped up, if you look carefully. Such as the total solar eclipse in the that Mel Gibson Aztec movie "Apocalypse". The whole event was over in ten minutes. Usually takes a couple of hours in the real world. I often get questions about this kind of thing and when you get the same topic brought up repeated - stars supposedly disappearing in a flash - you start to take notice. And they seem to be fixated on the idea and just don't want to know that it was just setting below a bank of clouds low to the horizon out to sea that they can't see in the dark...

[Astro_Bot]

The rise to peak brightness seems to be faster than the decline afterwards, but both appear to be best measured in days:

http://astronomy.swin.edu.au/cosmos/...a+Light+Curves

[Vegeta (Ibrahim)]

Ahhhh, Makes perfect sense now. thanks for the explainations.