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how hot is hot gas and hot clouds in space?

pgrieken wrote:how hot is hot gas and hot clouds in space?

If it shows up in x-rays or gamma-rays: multimillion degree Celsius.

http://antwrp.gsfc.nasa.gov/apod/ap081109.html
http://antwrp.gsfc.nasa.gov/apod/ap080823.html
http://antwrp.gsfc.nasa.gov/apod/ap080822.html
http://antwrp.gsfc.nasa.gov/apod/ap090205.html
http://antwrp.gsfc.nasa.gov/apod/ap081227.html
http://antwrp.gsfc.nasa.gov/apod/ap090317.html
http://antwrp.gsfc.nasa.gov/apod/ap090612.html
http://antwrp.gsfc.nasa.gov/apod/ap090321.html

HEAPOW: Outskirts (2009 August 31)

Suzaku Snaps First Complete X-ray View of a Galaxy Cluster
NASA Mission Pages: Suzaku (05.28.09)

In PKS 0745-191, the gas temperature peaks at 164 million degrees Fahrenheit (91 million C) about 1.1 million light-years from the cluster's center. Then, the temperature declines smoothly with distance, dropping to 45 million F (25 million C) more than 5.6 million light-years from the center.

neufer wrote:If it shows up in x-rays or gamma-rays: multimillion degree Celsius.

The interesting thing is that this doesn't mean that space in the region would be "hot" in the sense we usually mean it. It just means that these particles- which are actually quite sparse- have very high thermal motion. Consider, for example, the fact that the region of space where the ISS orbits has a temperature of about 1500°C. Sounds pretty hot, but there aren't enough particles to actually transfer that head efficiently. If you were in the shade of the ISS, you'd quickly freeze to death in that 1500° environment. I expect it is the same in many of these hot gas clouds that reach millions of degrees. Of course, particles that energetic will deposit deadly amounts of ionizing radiation into your body, so it might be a race between death by radiation and death by freezing to death in a million degree cloud!