Are there any mechanisms by which a cloud of gas can persist in space?

Question

I'm writing a SF story, and I need to be able to have clouds of gas persist in interplanetary space without them dissapating. I'll also occasionally want these clouds to 'drift' into and out of planetary orbits, infecting the atmospheres.

I've thought of and rejected electromagnetism, because that would probably ionise the gas, which I don't want, and as I understand it, gravity would not be strong enough to hold gas particles together. Any ideas?

I'd like to keep the story as much Hard SF (based on widely accepted current science) as possible, so I'm trying to avoid convenient speculative 'mechanisms'.

Not that I don't think many of these theoretical/speculative ideas won't eventually pan out, but I'd just like to keep the story grounded in our current understanding of reality, however inadequate it may be.

The gasses also HAVE to be interplanetary rather than interstellar. The story I'm writing doesn't feature any faster-than-light travel, so it's entirely localised to our solar system.

Answer 1

If you want the gas to stay together there would normally have to be some sort of mass in the centre of the cloud.
I have just read a book called "The Cloud" by Ray Hammond where the cloud rips the atmosphere off any planet it comes to contact with - it was attracted to radio signals.

Other options for making the cloud constant could be theoretical.

Super string?
Dark Matter (for the mass in the centre?)
Quantum singularity (black hole which the cloud circles)

I'm sure you can think of something better than these though!

Good Luck!


ADDITIONAL:

What about if the cloud was composed of a new element with a super dense atomic structure with huge gravitational potential. BUT the element also has electro-magnetic properties which prevent the atoms being condensed down into a liquid (as they are repelling each other if they get too close) - hence keeping the whole thing as a huge cloud?

Answer 2

From what science I understand about the gases your trying to come up with is called STELLAR GASES. These are the gases that float around after a Super Nova gone critical mass and imploded and or exploded. Now those stellar gases are also known as stellar nurseries. Creating new stars, planets, and all the heavy elements that couldn't exist till the star went super nova.

Now what no one talks about much is the clouds of DARK MATTER. Anti matter as it were. Do a little home work on those two subjects.

Answer 3

That's what a lot of nebula are - clouds of gas. Of course, any contact with (for example) the gravity of a planet would tear them to shreds.

Read "chindi" or "omega" by jack Mcdevitt. He has clouds held together by some unknown agency, and they terroize and civilized world they see.

Answer 4

It's your story. Make up your own laws of physics.