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How would the sun sound if....

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#26 GlennLeDrew

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Posted 13 October 2013 - 05:18 PM

ATM = atmosphere. One ATM pressure = 1013.2 millibars = 29.92 inches of mercury = 762mm of mercury = 14.7 pounds per square inch. (If I correctly remember those numbers, that is. :grin:)

#27 derangedhermit

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Posted 13 October 2013 - 07:56 PM

I found a few online formulae, but don't trust them to be correct, even approximately, with my limited understanding.

Needed assumptions / parameters:
- the issue chosen is sound transmission in outer layers of the sun
- the hydrogen is therefore monatomic / ionic (not diatomic molecular hydrogen)
- the adiabatic constant = 5/3 (for helium and monatomic hydrogen)
- ? helium / hydrogen ratio (affects average molecular mass)
- temp range:
-- photosphere 5,700K (75% hydrogen, 24% helium))
-- chromosphere 20,000K - 1,000,000K (% helium?)
-- corona 1,000,000K - 20,000,000K (% helium?)
- all layers are plasma, not gas (the formulae for speed of sound in a gas and a plasma are different)

High-altitude simulation studies indicate that human hearing is unaffected by use at down to 1/4 standard atmospheric pressure - both in sensitivity and localization (determining direction of sound source).

I'm not sure the speed of sound actually affects our ability to hear, except for localization and, I think, partial loss of stereo effects.

The impact of a hydrogen atmosphere on listening to your quadrophonic vinyl release of Tubular Bells while dropping acid is uncertain, but worth experimentation.

#28 StarWars

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Posted 13 October 2013 - 08:42 PM



Sound travels at 750 mph from 92 million miles... :foreheadslap: :o

#29 Mister T

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Posted 13 October 2013 - 09:17 PM

so it would sound like a 14 y.o.

:scared:

#30 derangedhermit

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Posted 13 October 2013 - 09:36 PM


Sound travels at 750 mph from 92 million miles... :foreheadslap: :o


According to one web toolbox, the speed of sound in 20,000K helium is about 19,000 mph, and the trip would take about 200 days. I think it isn't using quite the right formula, but anyway...

#31 Otto Piechowski

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Posted 14 October 2013 - 01:11 AM

Anthony,

What is "14 y.o."?

Otto

#32 Mister T

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Posted 14 October 2013 - 04:30 AM


Ottoman,

92,000,000miles/ 750 miles/hr /24hr/day / 365days/yr.

:graduate:

#33 Andy Taylor

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Posted 14 October 2013 - 01:32 PM

I'd like to think that it sounds like sizzlin' bacon... :lol:

Probably just very loud "white" noise.

#34 derangedhermit

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Posted 15 October 2013 - 03:00 AM

OK, I spent another 10 minutes on this. For those who want to pursue calculating the speed of sound in plasma, the Wikipedia explanation and equation is here.

Note that just below that link, the text says "When sound spreads out evenly in all directions in three dimensions, the intensity drops in proportion to the inverse square of the distance." This is more than halfway, geometrically, accurate for sounds coming from the "surface" of the Sun toward Earth. Given that drop in intensity, the distance involved, and the low pressure, it seems clear to me that no non-impulse sound coming from there could possibly be heard (or, probably, measured) by any creature on Earth. (Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)

So the answer is, unless it is a mighty explosion in our direction, much louder than any sound ever made on earth (e.g. Krakatoa) we would hear nothing.

If any part of this is wrong, I'm quite confident someone will be along directly to dispute it.

Along the way, I read about the transition of Voyager 1 moving from the heliosphere into interstellar space. You can listen to a recording. But it wasn't sound that was actually recorded, it was the vibration of electrons in the very thin plasma that changed when it entered interstellar space. Still, it was / is at least partially in the right frequency range for hearing.

Also there is a completely unrelated iOS and Android app called Plasma Sounds. Fun to play with, and free. My Google-foo is weak.

#35 GregLee1

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Posted 15 October 2013 - 10:49 AM

(Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)

Maybe someone could explain to me "sounds that look like sine waves"? The context here suggests that compression is somehow balanced with rarefaction. Or perhaps periodic is meant?

#36 derangedhermit

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Posted 15 October 2013 - 11:25 AM

(Pressure is relevant since it limits the amplitude of sounds that look like sine waves - the pressure cannot exceed 2x the ambient pressure, since it cannot drop below 0, but an impulse sound ("bang") does not have this limit.)

Maybe someone could explain to me "sounds that look like sine waves"? The context here suggests that compression is somehow balanced with rarefaction. Or perhaps periodic is meant?

Perhaps. I got tired of writing "non-impulse".

#37 Ira

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Posted 18 October 2013 - 02:27 AM

Let's recast like this: The sun is a continuous fusion reaction, like a Hydrogen bomb going off, with alot of other things thrown in. So, if you could hear it would it sound like a thermonuclear detonation of huge scale or not?

/Ira

#38 derangedhermit

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Posted 18 October 2013 - 04:52 AM

I think not, out at the photosphere. The fusion is only taking place in a small central core. At the outer layers, there's convection currents, very low frequency resonances, etc. An apparent "thermonuclear detonation of huge scale" at that location would blow all that away, literally, and it doesn't. It's more like a pot boilng out there. Remember it takes a very long time for the equivalent of a photon released at the core to work its way through all that mass to the photosphere.

When you got to an altitude, working from the outside in, where there was enough pressure to hear something, I can't imagine it is silent; but I have found nothing on what the spectral power density in the audible range might be.

#39 Mister T

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Posted 18 October 2013 - 05:19 AM

the nuclear fusion at the core is effective kept in a "pressure cooker" that is the gravity of the mass of the outer layers of the sun.

#40 Ira

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Posted 19 October 2013 - 05:27 PM

Bummer. This may make me give up astronomy. :crazy: :bawling: :thumbsdown:






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