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BISMARCK
2006-Oct-25, 05:14 PM
This CNN article (http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/index.html) mentions at the bottom that a supernova may have happened as close as .32ly from the early Solar System.

If it was a Type1a supernova, how bright would it be at such close proximity?

Celestial Mechanic
2006-Oct-25, 05:30 PM
This CNN article (http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/index.html) mentions at the bottom that a supernova may have happened as close as .32ly from the early Solar System. If it was a Type1a supernova, how bright would it be at such close proximity?
At least as bright as the Sun, if not brighter. Wouldn't want to be outside while that thing is above the horizon!

By the way, I don't want to sound like a language Nazi, but I see the phrase "close proximity" a lot. Is there such a thing as "distant proximity"? "Close proximity" is a bit redundant, sort of like "good progress". (Is there such a thing as bad progress?) :)

Denis12
2006-Oct-25, 05:48 PM
How bright will Betelgeuse be in our night sky when it goes Supernova?

And how bright will a Supernova be at 1 lightyear away from us? Will that be dangerous or not.

And as i have said earlier ,the firstcoming Supernova is far far overdue. Still nothing will happen until now.

StupendousMan
2006-Oct-25, 06:58 PM
This CNN article (http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/index.html) mentions at the bottom that a supernova may have happened as close as .32ly from the early Solar System.

If it was a Type1a supernova, how bright would it be at such close proximity?

Quick calculation: 0.32 lyr = 0.1 pc. Distance modulus m - M = 5 + 5log(0.1pc / 10 pc).
That comes to (m - M) = 5 + 5*(-2) = -5. Thus, apparent mag m = M - 5.

Given a rough value of M = -20 for a type Ia at max light, that makes the
apparent mag m = -25, which is indeed very close to the apparent magnitude
of the Sun.

One might conclude that the distance 0.1 pc was chosen for this reason ...

For the poster who wrote:

And how bright will a Supernova be at 1 lightyear away from us? Will that be dangerous or not.

I direct you to:

Matherly
2006-Oct-25, 07:07 PM
sort of like "good progress". (Is there such a thing as bad progress?) :)

Yes. Progress that is insufficent. For eaxmple, if I had to read chapters 1-23 for my history exam and I only made it to chapter 5, I would have made progress, but it would have been poor progress.

Celestial Mechanic
2006-Oct-25, 07:30 PM
Yes. Progress that is insufficent. For eaxmple, if I had to read chapters 1-23 for my history exam and I only made it to chapter 5, I would have made progress, but it would have been poor progress.
Point taken, but nobody ever reports it that way! Would you or anyone else say, "I've made some poor progress today"?

BISMARCK
2006-Oct-25, 07:30 PM
Conclusion: I suspect that a type II explosion must be within a few
parsecs of the Earth, certainly less than 10 pc (33 light years),
to pose a danger to life on Earth. I suspect that a type Ia explosion,
due to the larger amount of high-energy radiation, could be several times
farther away. My guess is that the X-ray and gamma-ray radiation
are the most important at large distances.

Well then it sounds like it would be quite bad for us. Also, since it would be roughly as bright as the Sun, how long would it stay that bright, or at least in that range? If it happened during the time of year when Earth would be between it and the Sun (assuming the supernova was in an area close to the Earth's orbital plane), how long would the Earth's "night" side be bathed in this supernova sun-like-light?

Tobin Dax
2006-Oct-25, 08:43 PM
Quick calculation: 0.32 lyr = 0.1 pc. Distance modulus m - M = 5 + 5log(0.1pc / 10 pc).
That comes to (m - M) = 5 + 5*(-2) = -5. Thus, apparent mag m = M - 5.

Given a rough value of M = -20 for a type Ia at max light, that makes the
apparent mag m = -25, which is indeed very close to the apparent magnitude
of the Sun.

One might conclude that the distance 0.1 pc was chosen for this reason ...

One might, but I doubt apparent magnitude had as much influence as you may be implying. Since they were using nuclear abundances to gauge this, and there are a number of errors involved, it's possible that was their resolution limit, or any of many other possibilities. The link between apparent magnitude and nuclear abundances from decay (apart from distance traveled) doesn't seem obvious to me.

Cougar
2006-Oct-25, 10:38 PM
...how long would it stay that bright, or at least in that range? If it happened during the time of year when Earth would be between it and the Sun (assuming the supernova was in an area close to the Earth's orbital plane), how long would the Earth's "night" side be bathed in this supernova sun-like-light?
"The mean type I curve, which is well defined by observations, consisting of a initial rise and fall (the peak) lasting until 30 days after maximum light, and a subsequent, slowly fading tail. The tail appears to be nearly linear when magnitudes are plotted against time, but magnitude is a logarithmic measre of brightness and the tail actually corresponds to an exponential decay of brightness with time. The decay rate of the type I correspods to a half-life of 50 days.

Type II SNe are subdivided into II-P and II-L on the basis of their light curve shape. Two-thirds of the observed type II SNe are II-P, which interrupt the initial declines from their peaks to enter a plateau phase of nearly constant brightness until 80 days after maximum light. A type II-L shows nearly a linear decline from its peak for 80 days after maximum light. The able data on the later phases of type II light curves are not well defined, but both II-P and II-L do appear to have slowly fading, linear tails,with a decay rate corresponding to a half-life of 100 days." -- Courtesy A Professional Perspective (http://www.supernovae.net/lcurv1.htm)

antoniseb
2006-Oct-25, 10:45 PM
If it was a Type1a supernova, how bright would it be at such close proximity?
I know you were using type 1a simply to provide an easy standard of brightness. Just so that most people know, this/these superova[e] were almost certainly not type 1a, which are from longer-lived stars.

Denis12
2006-Oct-26, 11:53 AM
How bright will Betelgeuse be in our night sky when it goes Supernova?

And how bright will a Supernova be at 1 lightyear away from us? Will that be dangerous or not.

And as i have said earlier ,the firstcoming Supernova is far far overdue. Still nothing will happen until now.

Very great ,thank you all

NEOWatcher
2006-Oct-26, 12:41 PM