Thread: Atmosphere to a galaxy

Could it be possible that a galaxy has an atmosphere?, for example, some theories describe dark matter as a ring around a galaxy that holds the stars together preventing them from "flying off into space" and keeping the speed/acceleration of distant stars relative to the speed/acceleration of inner stars close to the black hole. Some stars are so far away from their black hole/centre that by theory they should break away and fly off gradually, yet they maintain the motion due to what can only be described as "dark matter". What if dark matter does not exist and a galactical atmosphere exists due to the pressure and pull of trillions of stars creating an Earth like effect..

Just a thought...

hi jonny,i would doubt atmospheres could be associated with dark matter theory..let me explain further...dark matter is an attribute attributed to inflation theory based on a theory proposed by A.Guth.which described dark energy...dark matter is a further extrapolation,regarding the attributes associated...
.it is speculative,as all theories at this level are..however all these thing considered regarding your question...the answer is no...dark energy relies upon symmetry,which introduces a range of particles that are pposite of matter particles...ie,there are 24 equivalebt 'anti' particles,as they are described to exist outside the realms of matter as we know it,
so atmospheric condition are unaffected by dark matter.
Just to clarify;dark matter is a way to explain the apparent effect we observe,that indicate gravity is greater,by a factor of 4 to 5
than the observations show...the speculation is mostly due to the indications that we cannot see dark matter..but it does fit that dark matter accounts for the standard model of the universe

Dark matter has nothing to do with inflation.

The evidence of it comes from there being insifficient mass in galaxies to keep them together, as well as mulitple cases of dark matter causing gravitational lensing offset from the visible center of mass of galaxy clusters.

Hello Mr Wave.. =0)... Thanks for your reply... The trouble I have with this is that, as physicists are aware, Vera Rubin studied rotation curves and found outer stars to move at the same speed as inner stars. Yet gravity should loosen its grip the further away you are from the source.
Dark matter is the prime explanation to the galaxy rotation problem recognised by the majority of Physicists yet no explanation has ever been found......

As I though MeteorWayne.... Dark matter is irrelevant from inflation, inflation is fact. Dark matter still a theory.

All of which is correct. So it appears that Dark Matter exists. We have not been able to detect what it is yet, which is not surprising, since it only appears to interact with "normal" matter through gravitation, and an individual particle (like an atom or molecule) would individually have an undetectably small amount of gravity. The effect can only be seen when there's a whole lot of it together.

That's the theory right now anyway.

Wayne

As for my original question.... Could it be possible that a galaxy has some kind of atmosphere that holds the stars together, Like an outer ring?, as in me and you cannot leave the surface of the Earth without technology...

Originally Posted by Jonny

As for my original question.... Could it be possible that a galaxy has some kind of atmosphere that holds the stars together, Like an outer ring?, as in me and you cannot leave the surface of the Earth without technology...

A ring of matter (dark matter) would not be considered an atmosphere. You just can't make up new meanings of technical words on a scientific forum. Look up "atmosphere"

And the evidence suggests there is not a ring of dark matter around galaxies, but rather it is distrubuted throughout.

Vapor-Sphere, Stella-Vapor-Sphere, All the same area but around a different source, ie planetry/star...... I could name mine Galaxy-Pressure-Sphere, the question remains the same no matter what I call the layer!!

Is it possible that dark matter does not exist, giving way to a theory that some kind of layer surrounds a galaxy?

Which could explain the low gravitational pull of outter stars moving at the same rate as far-higher gravitional pull of inner stars to the black hole. It is merely a thought that intrigues me, if science or mathematics says my questions is ridiculous then i will abandom my theory. If not then the theory stands...

I agree,dark matter is nothing to with inflation theory,sorry that i implied that...its the dark word only that is common..it was however attributed with the gravity needed to explain observations of attributes that indicated larger gravity than the classical model predicted.and fully supports observations.dark energy is a way to explain inflation theory...
Now the original question,large gas clouds do exist in our galaxy,but the associated gravity with gas is relatively low compared to a planets gravity..also gas clouds are commonly seen in early star or pre star formations ..so i would say it would firstly depend on the 'local' conditions...but in a solar system it seems there is no outer gas/atmosphere.
It basically boils down to the gravity of gas is too low regarding the quantity of gravity needed regarding explaining the almost 5 fold increase indicated needed to explain observations...
'to paraphrase-i lacked the time to make this shorter'

theories are not in short supply though...but many fail the maths

Hey no problem Mr Wave. Easily done. =0)... I guess Its a question that is impossible to answer, the thought just intrigued me. I am no mathematician and neither claim to be a fully qualified Physicist, However I like everyone, wonders at the amazing thought of the universe and have questions/theories..... If we all thought the same done the same, the world would be a dull place!!... :-)...

The ideas are good,but through the mathematical process you can give ideas solid reasoning potential...ive tried it without maths,and it makes all the aspects impossible to explain at the level needed...although i have found the maths side is not as difficult as one might imagine...and a very powerful tool in theory

I'd like to learn the maths, I am very capable of maths... but only in the form of 9x9=81, 300x6=1800 and so on.... Haha!! As for
E=MC^2 Well thats the stuff I need to learn and dont even know where to start... There again, even that famous equation seems to be in doubt after recent findings If proven to be correct!!! I'll start learning maths when the results come in hey!! .. =0)

maths in physics beyond my ability to sum up..no pun intended...if it were that easy then i could teach it...but i realised its need,and tackled it one step at a time..basically you need to know the terms used...and the difficult bit,why those terms are used...many terms used are like a sort of short hand,that need previous steps to derive that term....plus a good understanding of the nature of the functions...etc.
it slowly makes more sense when you study it....you gotta put in the hours
As long as you enjoy the subject,thats the main thing...and ideas are the foundation of science...

I was thinking along the same lines but not that of an atmosphere. The earth has a magnetic core that protects us from any solar winds and radiation from the sun. The sun in return casts a heliosphere around the solar system to protect it from outter steller space winds, x-rays, gamma rays and what not. It just seems the further up the ladder we go nature would follow the same set rules/physics. Couldnt the black hole in the center of our milkyway galaxy have the same kind of effect that our sun and earth have. All casting an invisible sheath of protons/neutrons/electrons (what ever you may lable it) to protect the galaxy and all that resides inside it from something bigger or further out there. Just a side thought to add on to this thread.

Galaxies do have an "atmosphere": they have gas and dust all through them and it extends out a long way beyond the stars. They are also believed to have a similar distribution of dark matter: densest at the center but spreading out beyond all the visible material.

Note: people often misunderstand the description of a "halo" of dark matter as meaning it forms a ring. This just means that they may need to learn some Art History as well as some Astronomy.

Originally Posted by Strange

Galaxies do have an "atmosphere": they have gas and dust all through them and it extends out a long way beyond the stars. They are also believed to have a similar distribution of dark matter: densest at the center but spreading out beyond all the visible material.

Note: people often misunderstand the description of a "halo" of dark matter as meaning it forms a ring. This just means that they may need to learn some Art History as well as some Astronomy.

That "halo" part always confused the devil out of me, I hear "halo" and my brain images a torus. Thanks for clearing that up. Really, it confused the piss out of me how observations lined up with additional matter outside the galaxy. Duh???????????
When you said "Art History" I recalled middle ages depictions of Saints.
In addition I'm assuming that someone has already done the calculations for the relevant relativistic temporal dilations, and spatial contractions? That these are not the cause of the anomalous orbital velocities in galactic rims?

Originally Posted by GiantEvil

When you said "Art History" I recalled middle ages depictions of Saints.

Exactly; they had "solid" haloes. They looked like disks in the paintings but were supposed to represent a sphere of "light" around the person. The angelic "ring" halo is a very modern idea.

In addition I'm assuming that someone has already done the calculations for the relevant relativistic temporal dilations, and spatial contractions? That these are not the cause of the anomalous orbital velocities in galactic rims?

Yes, this has been done. It is far too small to account for the observations.

Originally Posted by brane wave

and ideas are the foundation of science...

True... and so is mathematics. That is why many, including me, are in the long process of learning heavily used applicables.

Once I master a few more subjects, I finally might able to decipher one of Markus Hanke's posts!

The galaxy as a whole has a great deal of gravity, and I'm sure that has a great deal to do with keeping those outer rim stars in orbit.

But have any of you heard of the Galactic bow shock theory?

Out-of-This-World Hypothesis: Cosmic Forces Control Life on Earth | Space.com

If this theory is even a little bit correct it means there is enough interstellar intergalactic particle density to cause it (as thin as it might be). Even very minute numbers of particles can really add up over stellar volumes & distances. It could be possible to make a case for calling it an atmosphere of sorts.

What if dark matter does not exist and a galactical atmosphere exists due to the pressure and pull of trillions of stars creating an Earth like effect..

if this were the case then we would most likely be able to detect it using instruments sensitive to EMR. that we don't detect it with these instruments is the reason we call it "Dark". so we know it is not an "atmosphere".

Originally Posted by Jonny

As for my original question.... Could it be possible that a galaxy has some kind of atmosphere that holds the stars together, Like an outer ring?, as in me and you cannot leave the surface of the Earth without technology...

Well yes, but it is hardly an atmosphere. Space-time continuum is ever expanding. However this doesn't change the law of physics. Hence gravity remains the same. As the range of gravity (or the curvature of space-time) remains the same galaxies keep roughly the same size, whereas the distance of galaxies amongst eachother is moving away from eachother. In comparison, galaxies are held together by gravity.
Also the only other force that would have a range that can be called of any kind of atmosphere is light. Just like our planetairy system has a field produced by the sun of cosmic rays etc. That 'shields' us from interstellair space (the galaxy). Only Voyager 1 (or two I forgot) is going to leave that atmosphere any time soon. But what happens to that interstellair wind outside our galaxy? To my knowledge we just don't know.

Our galaxy is surrounded by a giant bubble of hot plasma extending hundreds of thousands of light years.
NASA's Chandra shows Milky Way is surrounded by halo of hot gas

This is a recent discovery, and the implications are mind-boggling. Likely the same is true for all galaxies, and all galaxies are entwined and connected by the filaments that make up these truly vast structures. This intergalactic or universal atmosphere operates at a temperature much hotter than the surface of the sun, and possesses electromagnetic properties about which we can only speculate.

Respectfully submitted,
Steve