B Temperature of gaseous nebulas

Greetings,
I read with interest some of the reports and studies of the "measurement" of the temperature of interstellar gases(H2, O2 etc) surrounding some gaseous nebulas(nebulae). Some reported temps. are in the thousands of degs. K. I was wondering how a solid object traveling at high speed would be able to traverse these regions without suffering "meltdown". as these temperatures are far higher than any metal or alloy we know can withstand.
I realise that these gases are VERY dispersed generally but could there be pockets of high enough density(relative to space) that could disrupt a speeding body(spaceship, asteroid etc). Is the reported "temperature" what we understand as temperature on earth? Would not the atoms themselves be disassociated by such high temperatures and be unrecognisable by our telescopes(radio, etc)?
Thanks for your interest.!
 

DrClaude

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Combined with the low density is the low energy content. So you have to consider how much time it will take for the gas to heat up the object and by how much it will cool down when heating the object.

I am not a specialist intros field, but I would assume that molecular gases are much colder, and that it is ionized gases that make up the thousand-K clouds.
 

phyzguy

Science Advisor
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Greetings,
I read with interest some of the reports and studies of the "measurement" of the temperature of interstellar gases(H2, O2 etc) surrounding some gaseous nebulas(nebulae). Some reported temps. are in the thousands of degs. K. I was wondering how a solid object traveling at high speed would be able to traverse these regions without suffering "meltdown". as these temperatures are far higher than any metal or alloy we know can withstand.
I realise that these gases are VERY dispersed generally but could there be pockets of high enough density(relative to space) that could disrupt a speeding body(spaceship, asteroid etc). Is the reported "temperature" what we understand as temperature on earth? Would not the atoms themselves be disassociated by such high temperatures and be unrecognisable by our telescopes(radio, etc)?
Thanks for your interest.!
A couple of points:
(1) The temperature of the interstellar medium can be even higher than thousands of deg K. In some regions, the temperature can be 10^6 K or even higher.
(2) These temperatures are the same thing as we mean by temperature here on Earth, but as DrClaude said, the density is so low that the heat transferred to a solid object would be very small, so would not result in melting.
(3) The atoms themselves are in fact dissociated by the high temperatures. This is what we mean by a plasma, where the atoms have been dissociated into ions and free electrons. However, this does not mean that they are "unrecognisable by our telescopes". Ionized atoms still generate atomic transitions with well defined energies, so we can see emission lines from these ionized atoms. The attached spectrum shows emission lines from a nebula. O-III, for example means it is an emission line from an Oxygen atom from which two electrons have been stripped. Similarly, Ar-iV is an emission line from an Argon atom from which three electrons have been stripped.

bv1r.jpg
 

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sophiecentaur

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pockets of high enough density
I can't think of a mechanism to achieve this when the normal gas Laws will be govening the behaviour of masses of gas in the absence of 'walls'. I could imagine that a mass of gas at high velocity - say from an explosion - would 'contain' more significant momentum.
 

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