Astonishing Image Of Shockwaves From A Dying Star

angkor writes: "This is worth a look: "A new image from the Hubble telescope shows a pair of supersonic shock waves created when gas from a collapsing star hits surrounding clouds of cosmic gas and dust." And an enlarged image for your desktop."

Supersonic?

[j_w_d]

Is "supersonic the right word here?

Re:Supersonic?

[stevelinton]

Yes, really. There is a cloud of (very diffuse) dust and gas there, and, provided you look over large enough distance scales, it makes sense to talk of sound waves and the speed of sound in this gas. Over small scales, this breaks down because individual atoms can don't collide enough.

A wave of more gas (also very diffuse) is hitting this cloud, faster than the speed of sound in the cloud, and pushing this "shock wave" in front of it.

Is there something I'm missing?

[Sklivvz]

On the enlarged photo page it reads:
"an event that happened about 800 years ago in a constellation 5,000 light-years away"
Well, if the event took place 800 years ago, and the distance is 5,000 ly, then we should wait another 4,200 years for the light of the event to reach us... It doesn't make sense!

Cheers

Re:Is there something I'm missing?

[windi]

If you look at the caption, it says in parentethes or 5,800 years ago in absolute time, so the star collapsed 5,800 years ago, and now, the shockwaves have beem travelling for 800 years.

Reading the caption under pictures sure helps you understand them. :-)

Re:Is there something I'm missing?

[Raumkraut]

Actually, the additional comment about 5,800 years absolute time seems to appear and disappear randomly when you refresh the page...

Or it seems to for me, anyway.

No smell in space?

[GreyPoopon]

Luckily, in space, there is no sense of smell.

Would somebody care to explain this? Perhaps I don't understand how smell works, but I never thought that oxygen was a required factor. If you could overcome that fact that you'd either freeze to death or some other nasty cold-vacuum related fate if you exposed your nose in space, should you still be able to pick up the displeasure of sulfur gas?

Re:No smell in space?

[CheshireCatCO]

Oxygen isn't the factor, methinks, it's the tenuousness of the gas. For astronomers, one particle per cubic centimeter is high for elements like sulfur. Even the Io plasma torus, dense by astrophysical standards, is only around 1000 per cubic centimeter in sulfur. If you mixed this gas in with normal, sea-level air, that would be around one part in 1016. There just isn't enough there to trigger the olfactory receptors strongly enough to be detected.

High-res image

[DavidBurns]

Nice post, but the high-res image is a modest .jpg. Here's a link to JPL, where you can download the 2MB .tif: http://www.jpl.nasa.gov/images/wfpc/index.html [nasa.gov]