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Betelgeuse SN

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#1 Qwickdraw

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Posted 04 July 2013 - 08:19 AM

Hypothetically (or not so much) if Betelgeuse went SN what would the long term and short term impact be on astronomy both visual and radio. I assume there could be no meaningful astronomy, manned space exploration for centuries.
By most calculations it appears life on Earth would be relatively safe from immediate effects but what about long term effects. What about life cycles of plants and animals that are so in tuned with the night sky and associated lunar phases, etc. Would the additional LP kill off a lot of these species or could evolution prevail in an environment that has chaged so rapidly?

#2 deSitter

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Posted 04 July 2013 - 08:54 AM

There would be no effect, other than to startle and amaze us. Like all supernovae it would fade within a few months and a planetary nebula would appear where Orion used to have a shoulder.

Brightness? Full moon!

Such a thing would be a tremendous boon to neutrino physics.

-drl

#3 deSitter

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Posted 04 July 2013 - 09:32 AM

The only supernova candidate close enough to rip away some of the ozone layer is IK Pegasi at 150 LY.

http://en.wikipedia.org/wiki/IK_Pegasi

-drl

#4 GlennLeDrew

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Posted 04 July 2013 - 11:43 AM

If we assume the peak brightness of Betelgeuse as a supernova to reach -18 magnitude absolute, it's apparent brightness would be about -12m, or very nearly as bright as the full moon. If this occurred near the summer solstice, it would be swamped by the Sun's glare, and one would have to wait a couple of months or so to see it in a dark sky.

#5 dyslexic nam

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Posted 04 July 2013 - 11:57 AM

Curious - when you guys say that it would be as bright as the full moon, do you mean something that puts out as much light as the total light reflected by the moon, or that the small portion of sky occupied by the SN would emit the same amount of light as that reflected by a similarly sized portion of the full moon?

Also, would the pinpoint of light appear substantially bigger from our prespective, or simply a lot brighter? (which may equate to the same thing since BG already appears 'larger' than other stars - presumably as a result of its brightness)

I am having difficulty visualizing a star/point-of-light that emits the same total brightness as a full moon.

#6 deSitter

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Posted 04 July 2013 - 02:08 PM

"As bright as the full Moon" means that if you look on the ground and around and the environment, you will see shadows and light more or less as you would during the full Moon. What will be different is that the source of this light will be, not an extended disk, but an infinitesimal point - the shadows would be absolutely razor sharp, and refractory phenomena would likely be seen, as they are during the last moments before a total solar eclipse, when the angle subtended by the remaining Sun is small (the famous shadow bands, which I have seen but cannot describe).

-drl

#7 gavinm

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Posted 04 July 2013 - 03:19 PM

Not a planetary nebula, a supernova remnant ;)

#8 llanitedave

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Posted 04 July 2013 - 08:41 PM

It should have the light curve of a fairly typical Type II supernovae, just much brighter to our eyes. The peak brightness would last just a few weeks, but a plateau phase lasting about 100 days keeps it at some 10% of its peak luminosity, until it undergoes a more steady decline. I would guess that post-supernovae, Betelgeuse might remain visible to the naked eye for a couple of years.

#9 Rick Woods

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Posted 04 July 2013 - 09:38 PM

By most calculations it appears life on Earth would be relatively safe from immediate effects but what about long term effects. What about life cycles of plants and animals that are so in tuned with the night sky and associated lunar phases, etc. Would the additional LP kill off a lot of these species or could evolution prevail in an environment that has chaged so rapidly?


You're wondering about the harmful (but subluminary) radiations unleashed by a supernova occurring only 540 ly away, right? What about that, any physicists here? Would we be in trouble sometime down the road?

#10 GlennLeDrew

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Posted 04 July 2013 - 11:06 PM

In my feeble understanding, a type II SN (such as Betelgeuse) does not emit as fierce a dose of harmful short wavelength radiation as does a Type Ia SN. And so at ~500 l-y should pose no threat. Even a type Ia SN might have to occur within 100 l-y or so in order to be worrisome.

However, I'm given to understand that chemical signatures consistent with the relatively distant SN of 1006 and 1054 have been found at suitable depth in ice caps. Makes one wonder about the effects of gamma rays...

#11 deSitter

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Posted 04 July 2013 - 11:08 PM

The only danger is from having the ozone layer stripped. That would require a SN within 30 or so LY. There are no candidates for such. Here is one catastrophe we will not face :)

-drl

#12 deSitter

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Posted 04 July 2013 - 11:16 PM

There would be many extraordinary optical phenomena associated with a nearby SN. Because the light is a point source, diffraction effects would be easy to see. The star would twinkle like mad and cover the ground with weird shifting ghostly patterns corresponding to atmospheric turbulence. When seen through tree leaves, the star would continuously appear and disappear in the gaps instantaneously, creating a strange strobe-like effect that would be utterly hypnotic and weird. Unlike the reflected light from the Moon, this would be extremely shockingly blue-white, unless near the horizon, when a kaleidoscope of colors would appear in rapid random succession. This object would utterly dominate the night sky and landscape with its weird effects. It would be worth losing Betelgeuse to witness such a thing. It would also have a profound effect I think on human appreciation for "out there".

-drl

#13 llanitedave

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Posted 04 July 2013 - 11:47 PM

Question here, Danny: The blue-white color would only last during the initial phase of the explosion when the shock wave is exiting through the star's photosphere -- is that correct? It should redden as the expansion continues, but I don't know how color change relates to the light curve itself.

#14 deSitter

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Posted 05 July 2013 - 04:26 AM

Yes it will naturally redden as it expands and thermalizes - the early stages have a lot of x-rays and gamma rays that are down-scattered toward ultraviolet - that's the danger to the ozone layer. No one would ever look at Sirius or Rigel the same way again after seeing such a blue demon in that part of the sky!

-drl

#15 deSitter

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Posted 05 July 2013 - 04:29 AM

..one other fact - because Betelgeuse is so close to the equator, the entire world would get to enjoy the show. But let's hope it happens during July!

-drl

#16 Qwickdraw

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Posted 05 July 2013 - 06:06 AM

It is interesting to hypothesize about some of the various consequences if this happened as it could happen just as easily tomorrow as 1,000 years from now. It would no doubt be the celestial event of a millennium. I wonder how our own atmosphere would react. Would we have worldwide aurora borealis? How is a star's mass estimated without orbital data? Is it just that, a best guess?

#17 deSitter

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Posted 05 July 2013 - 07:27 AM

We would get a lot of UV light from it - this would interact with the ozone layer, but not enough to cause any real problems for life. There would not be an aurora - those are caused by charged particles diving into the atmosphere.

-drl

#18 Qwickdraw

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Posted 05 July 2013 - 07:38 AM

We would get a lot of UV light from it - this would interact with the ozone layer, but not enough to cause any real problems for life. There would not be an aurora - those are caused by charged particles diving into the atmosphere.

-drl


kind of ironic to me that a solar flare from the sun can cause an aurora but a complete star blowing up would not?

#19 llanitedave

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Posted 05 July 2013 - 08:19 AM

Well, the charged particles travel more slowly than the electromagnetic radiation from the flare, and they're susceptible to magnetic fields. In fact, the aurora is caused by the Earth's magnetic fields deflecting the charged particles from their initial path.

Charged particles from Betelgeuse simply wouldn't make it this far, at least not en mass, and not in a human lifetime.

#20 Qwickdraw

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Posted 05 July 2013 - 08:32 AM

Well, the charged particles travel more slowly than the electromagnetic radiation from the flare, and they're susceptible to magnetic fields. In fact, the aurora is caused by the Earth's magnetic fields deflecting the charged particles from their initial path.

Charged particles from Betelgeuse simply wouldn't make it this far, at least not en mass, and not in a human lifetime.


Thanks for the explanation.

#21 GlennLeDrew

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Posted 05 July 2013 - 09:47 AM

If we assume just for the same of argument a round, constant velocity for the debris from a SN as 1,000 km/s, that's equivalent to 1,000 pc//Myr (from the very handy conversion factor of 1 km/s being very nearly 1 parsec per million years), or 160 pc/160,000 yr. In other words, it would require a good 160,000 years for any ejecta to reach us, by which time it would probably be rather less dense than our own solar wind anyway.

And would a Type II SN necessarily be really bluish early on? And if so, for how long? I don't recall SN 1987A being reported as ever bluish. (I did see it from Australia when at peak brightness, and it was a yellowish hue.)

#22 Rick Woods

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Posted 05 July 2013 - 10:13 PM

..one other fact - because Betelgeuse is so close to the equator, the entire world would get to enjoy the show. But let's hope it happens during July!


I hope it doesn't happen at all - I like Orion with two shoulders!

#23 llanitedave

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Posted 06 July 2013 - 12:06 AM

And would a Type II SN necessarily be really bluish early on? And if so, for how long? I don't recall SN 1987A being reported as ever bluish. (I did see it from Australia when at peak brightness, and it was a yellowish hue.)


I'm really curious about the answer to this question, for reasons of my own.

#24 StupendousMan

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Posted 06 July 2013 - 01:21 AM

First, you can read a short description of some of the risks associated with nearby SN (none are significant for Betelgeuse) at

http://stupendous.ri...ers/snrisks.txt

Second, yes, even an extended red giant would appear blueish-white for a short time after the explosion. The shock wave which passes through the stellar envelope will shock the gas of the envelope, heating it to around 100,000 Kelvin. It will cool back down to ordinary temperatures within a few days.

#25 deSitter

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Posted 06 July 2013 - 12:30 PM

..one other fact - because Betelgeuse is so close to the equator, the entire world would get to enjoy the show. But let's hope it happens during July!


I hope it doesn't happen at all - I like Orion with two shoulders!


We could just rename it Orin.

-drl






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