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Milky Way Is Surrounded By Halo of Hot Gas
New submitter kelk1 writes "If the size and mass of this gas halo is confirmed, it also could be an explanation for what is known as the 'missing baryon' problem for the galaxy [...] a census of the baryons present in stars and gas in our galaxy and nearby galaxies shows at least half the baryons are unaccounted for [...] Although there are uncertainties, the work by Gupta and colleagues provides the best evidence yet that the galaxy's missing baryons have been hiding in a halo of million-kelvin gas that envelopes the galaxy."
that envelopes the galaxy
Surely you meant to use the verb, i.e. "envelops".
Forming a letter of galactic proportions without a stamp.
http://en.memory-alpha.org/wiki/Galactic_barrier
more cowbell
Depends on how dense it is. If you immerse yourself in water at 100C (boiling point for you imperial scumdogs :) you won't last long at all, but in dry air at 100C you can survive for substantially longer. If the gas was so sparse that you might only hit a molecule every few seconds or so then the temperature might not matter so much. The article hints that the density is low "The estimated density of this halo is so low that similar halos around other galaxies would have escaped detection." but that doesn't really help in absolute terms.
(or maybe you're making a joke... i don't get the reference in the first line you posted)
retain it's 1,000,000K for 14,000,000 years?
First, that's 14,000,000,000, not 14 million.
The key is how undense it is. When a physicist talks about "temperature" in this context it's just short-hand for "average velocity"... it doesn't necessarily imply thermal equilibrium, even. So 1e6K means a high average velocity. Now, if it were a dense gas there might be collisions that would do things like excite electrons into higher states, which would then decay by emitting photons (light), and so the gas would lose thermal-kinetic energy over time.
In a sufficiently diffuse gas, loss processes like this are very slow because the chances of collision are very slow, so it can stay "hot" (that is, have a high average velocity) for a long, long time.
Blasphemy is a human right. Blasphemophobia kills.
As a plasma physicist, I'm not bothered or concerned about them calling it gas. When interacting with the general public to discuss plasma related research, sometimes you find yourself having to make a choice between trying to teach a person what a plasma is, or teaching them what you are doing with it. Attention spans, and time/space are sometimes limited with such interactions and you have to choose your priorities.
Temperature (in Kelvin) is actually more useful in astrophysics and thermodynamics of plasmas. It wraps up a bunch of messy real world constants into one number, and also neatly describes the behavior of the volume of gas as a whole, rather than forcing the analyst to perform a lot of messy integrating and averaging of distributions of actual velocities in three dimensions.
Think about it this way. No one is really interested in how fast a specific particle is moving. They're more interested in how the Thermal Energy of the gas couples with other systems.
A galactic halo would be coupled very, very, (very^18) poorly with other systems, at least conductively. And probably even worse convectively, given the scales involved. Radiatively, I don't know near enough about the behavior of these particles to talk about why, but if it's stayed that hot for the life of the universe, effectivelt, then apparently its either not coupled to another system, coupled far more strongly to itself than anything else, or somehow not stimulated to emit blackbody radiation... or all three of the above.
I can see the fnords!
Hold on a second... so they just discovered the Galaxy is surrounded by gas that's the same temperature as the surface of the sun, and is 300,000 lightyears across... possibly extending far into other galaxies... I'm going to take a wild stab here and say that, if that's true it probably pervades the entire universe... Isn't this the biggest scientific discovery in the past decade? What effect does this have on Dark Matter, Dark Energy, etc... etc...
It has been known for a long time that the intergalactic medium is hot enough to be ionized. That part is not news. The thing that's news is that the hot gas makes it possible to account for the baryons in the Milky Way halo, which were previously undetected.
...has Rush Limbaugh really gotten that big?
The thing that's news is that the hot gas makes it possible to account for the baryons in the Milky Way halo, which were previously undetected.
The thought that we're just the 0.1% of the dirty precipitate at the bottom of the gravity well is a tad humbling. Not that much isn't when you look up from the T.V. to a clear night sky.
Galaxies are apparently quite dynamic things: a rain of in-falling gas to make new stars, pressure from new stars pushing back, dust build up from all this nucleosynthesis, blackhole cores that cycle on and off. One paper I read even claims this is the beginning of the 'green' period for the Milky Way. The conditions for life will be come more abundant: the number of long-burning dwarf stars like the sun continue to rise as a fraction of the stellar population while the dust percentage (you know, planets) rises at the same time a lot of the big super- and hyper- novae are over with.
However, longer term prospects seem bleak if the dynamic gas is all consumed or blown away. Eventually stellar production would grind to a halt. The green galaxy would give way to white and red dwarfs floating amid other stellar corpses and thinned gas.
I have to wonder if the temperature and environmental coupling of this gas is enough to become a future raw star material resource? I mean, we're talking about 99.9% of the matter here and it's already gravitationally bound. Could someone model long-term in-fall of this ionized matter? Could it cool fast enough or even at all to beat the predicted 'big rip' from dark energy and give the galaxy a 2nd, 3rd, etc. childhood?
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