So this is where Arctic Penguin vacations....

[Andonyx]

http://www.smh.com.au/articles/2003/02/20/1045638427695.html


Five thousand light years from Earth in the constellation of Centaurus, the nebula, a gas cloud formed from a dying star, has a temperature of minus 272 degrees.

[arcticpenguin]

I think I can see my igloo in this photo ...

[espritch]

It appears that the ultra-cold gas is flowing from the nebula's central star so fiercely, at 140 kilometres per second, the background radiation is simply blown away.

So how can the gas be blowing that fast and not be heated by friction? And what's blowing it? :confused:

[jj]

I want to know what's keeping it cold, myself.

Tez?

[Andonyx]

Originally posted by jj
I want to know what's keeping it cold, myself.

Tez?

Friction?

Keeping it cold?

Nothing.

Friction? What exactly do you think this is rubbing against? It's empty space? There's no friction to be had.

Cold?

Cold is the absence of heat. You can ask what's keeping something hot, in other words hotter than background radiation. Thequestion is why is it any hotter than that.

Cold, everything becomes cold. Ultimately.

Nothing "Keeps" anything cold.

[Soapy Sam]

Is this just a super version of expanding-gas refrigeration? Do the thermodynamics of "normal" gas laws stand up under these conditions?

And what IS a penguin doing in the Arctic anyway?

[espritch]

Cold is the absence of heat. You can ask what's keeping something hot, in other words hotter than background radiation. Thequestion is why is it any hotter than that.

Cold, everything becomes cold. Ultimately.

Nothing "Keeps" anything cold.

My question had more to do with the fact it was moving so fast. Getting gas moving that quick require energy, and where you have energy you generally have heat. APOD had this same picture displayed recently.

http://antwrp.gsfc.nasa.gov/apod/ap030220.html

The symmetric cloud appears to have been created by a high-speed wind of gas and dust blowing from an aging central star at speeds of nearly 600,000 kilometers per hour. This rapid expansion has cooled molecules in the nebular gas to about one degree above absolute zero - colder than even the cosmic background radiation - making it the coldest region observed in the distant Universe.

So I guess the star is providing the energy to push the gas. The gas expands so fast that the expansion cools it (the way expansion of Freon in a refrigerator coil causes it to loose heat). I agree (in hind sight) that friction probably wouldn’t apply unless the gas being expelled encountered gas previously expelled. I guess the measured temperature applies only to the expelled gas, not to the central star. The original link didn’t really make this clear to me.

And what IS a penguin doing in the Arctic anyway?

Avoiding the skuas?

[shanek]

Originally posted by espritch
Avoiding the skuas?


Q: What's the penguin's natural defense against polar bears?

A: They live on the other side of the world from them.

[Samurai Muppet]

Originally posted by Andonyx



Nothing "Keeps" anything cold.

hOW ABOOUT A REFRIGERATOR ?:D

[tim]

Originally posted by Samurai Muppet


hOW ABOOUT A REFRIGERATOR ?:D

Nah - that just stops stuff getting warm