# KILO-MACH SONIC BOOM probed in fireball embers of 1572AD SUPERNOVA

Many thousands of years ago, far away in the constellation Cassiopeia, a white dwarf star blew up with cataclysmic violence. Much, much later, in the year 1572 when good Queen Bess was on the throne, the light of the supernova reached Earth. Now, astronomers probing the vast cloud of slowly cooling gases left behind say they …

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#### nose

was probably brass (or he used different noses on special occasions)

#### Globetrottered

It looks like somebody Globetrottered up that Explosion and made in an Implosion

So just to be clear, the supernova happened a long time ago, in a galaxy far, far away...?

a long time ago in our galaxy, far, far away.

#### 2-3000 light years

is not that far away.

#### In Space, No-one Can Hear You Explode

Sound travels at different rates through different media. The article says "300 times the speed of sound" and "hurtling inwards at no less than Mach 1,000." So my questions are what is the speed of sound in this environment and is there enough gas to allow sound to propagate? I would assume that the numbers given are in comparison to the typical speed of sound in Earth's atmosphere, although I would posit that they should be put into proper Register units of measure.

#### Re: In Space, No-one Can Hear You Explode

I want to know what Mach 1000 is in Linguine per fortnight.

#### Re: In Space, No-one Can Hear You Explode

Thanks for this! When I read the headline I thought, "Big whoop-de-doo - given the speed of sound in a near-total vacuum, I and my trusty walking stick can still beat Mach 1000 easily" :)

#### Mach 1000

Converts to 2940105651840 lilnguine per fortnight.

Yes, I was bored.

#### Re: Mach 1000

Yes, one significant figure becomes 12 significant figures after conversion...

#### Re: Mach 1000

Or merely 0.011% of the maximum velocity of sheep in a vacuum.

#### Re: In Space, No-one Can Hear You Explode

"given the speed of sound in a near-total vacuum, I and my trusty walking stick can still beat Mach 1000 easily"

Except they're not referring to the speed of sound in a vacuum, they're referring to the speed of sound through the interstellar medium

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

#### "KILO-MACH SONIC BOOM PROBED IN FIREBALL"

Ryu and Guile haven't been fighting again, have they?

#### </science> Holy crap...

...that's just a super cool picture. <science>

#### "Mach 1,000 X-ray brakelight blast boom fireball supernova remnant boffinry"

I have found my new band name.

Brakelight blast boom fireball ... Sounds like an ordinary day in the traffic here where I live.

Anyway, the thing that I was wondering: how does a white dwarf star explode? Is it one of them stars on the edge of collapsing into a neutron star/white dwarf and the universe illegally dumped its building rubble there, tipping it over the edge? I have to know.

Some seriously Star Warsey sounding stuff ==>

Hey kids....FREE X-RAYS every time Cassiopeia goes by ! ! !

#### ex nihilo nihil fit - conceptual black hole emissions

The conceptual difficulty here is how any such reverse shockwave might be big enough to be noticeable. How would one measure the presumed shockwave in emptying a bucket of water - presumably the shockwave due to air impeding your emptying the bucket?

What is beyond dispute is that if I hold a telescope to my eyepatch (Lord Nelson, natch, rather than Pirate Bay) no-one can say I don't see unicorns.

Shock and awe. Iraq 2003 meet cosmology 21st century style.

#### not so fast

The cited Mach number refers to the shock velocity over the velocity of sound in a shirt-sleeve atmosphere and has nothing to do with the sound- or Alfven- velocity in the hot collisionless magnetoplasma of Tycho's SNR

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