Milky bar

It has been confirmed that the Milky way is a barred spiral

http://www.news.wisc.edu/newsphotos/milkyway.html

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Beautiful picture isn't it?

I think I need to brush up my knowledge about formation of bars. Amazing stuff

 

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The smoke ring galaxy, its worth a look
http://spaceflightnow.com/news/n0209/06hubble/

 

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Any galaxy with a 'Bar' in it, can't be too bad.

Okeydoke

 

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Hey anomalous, I like that picture a lot. Though, i will be "nationalist" and say that I prefer the picture of our Milky Way

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I was amazed today to discover that the bar of the Milky Way is tilted at a 45 degrees angle with respect to the plane of the galaxy. It could seem that the bar should be coplanar with the disk, but surprise, is tilted.

http://www.space.com/scienceastronomy/050816_milky_way.html
"Churchwell's team also found that the bar is oriented at about a 45-degree angle relative to the main plane of the galaxy, in which the Sun and the other spiral-arm stars orbit."

 

I see no reason for the bar to be coplaner. The spiral arms of any galaxy are a result of colisions of two galaxies.

Initailly our galaxy must have been a evenly distributed (stars) spherical disk. Then some gaint galaxy must have passed by it making it elongated barlike armed galaxy. Then some other galaxy must have colided with it by the side just enough to leave the central bar intact and noncoplanar, the sipral arms were formed due to its rotations and change in speed of outer stars revolutions.

I wonder what will happen when Andromeda colides.

 

It will probably mess up the 'Bar' a little I would guess.

Okeydoke

 

Actually, there are 3 competing theories for the formation of arms in spiral galaxies. One has been named by you, the collision of 2 galaxies. The other two are:

a)Self-propagating star formation (Mueller, Arnett, 1976): Basically, a supernova explodes and triggers star formation in its surroundings. Now, the new stars are rotating around the galaxy, so those closer to the center will be ahead of those that are in the periphery, giving the appearance of an arm

b)Density waves (Lin, Shu, in the 60s): These waves travel radially through the galaxy, compressing gas clouds. The compressed clouds are likely to start star formation, so we see the arms because there's a boom of stellar formation in that zone. Density waves themselves are probably initiated by the asymmetric gravitational field of a central bar structure or by gravitational disturbances caused by neighboring galaxies, or by a combination of both


I've found this nice page explaining the 3 theories in more detail
http://home.cc.umanitoba.ca/~umcoll14/minorproject.html

I've always preferred the density wave theory, moreover, is the mainstream

 

How do they know what the Milky Way looks like from the outside?

 

Thanks for that gr8 info. But your favourite theory is possible only if there are always two primary arms.

 

Hum,
While it may be true that the spiral arms of the Milky Way were the result of collisions or mergers with other satellite galaxies; it is wrong to say the spiral arms were formed due to its rotations and change in speed of outer stars revolutions.
The arms are the result of density/shock waves from supernovas travelling through the disk. The arms are just an illusion that picks out bright, short-lived star.
Our sun for example orbits once every 225 million years; if it were one of more massive and bright short-lived `spiral arm` stars, then in less than a million years time it would explode before travelling less than 2 degrees of its orbit…

 

I thought that opur solar system was farther from the center or closer to the outer part than shown in the photo.

Did the artist misunderstand or was he allowed to pick the postion himself without much infomration from astromers?

 

Some people say 2/3, other 3/5 from the center, so IMHO, is not that bad

 

Here's a delightful account about how spiral density waves are generated

http://physics.csustan.edu/Ana/galaxtypes.htm


"The analogy would be when you throw a rock in water, waves are created that move across the pond surface; they move outward in concentric rings from where the rock struck. If the pond is also rotating, how do the waves move?

Lindblad found in the 1960s that they are spiral shaped

Russians tested the density wave theory by throwing rocks into water filled pie pans that rotated on a turntable. They found that the water wave patterns were indeed spiral"


I need to do also this experiment. Is fascinating that you can create a galaxy in your own kitchen

 

Thanks for that gr8 info. But your favourite theory is not possible if there are always two primary arms.

Which my eyes can clearly see, unless I have brain damage in my visual cortex.

 

I've managed to find the technical paper about this issue
http://arxiv.org/abs/astro-ph/0508325

"First GLIMPSE Results on the Stellar Structure of the Galaxy"

The bar is a linear bar tilted by 44 degrees to the Sun-Galactic center line

 

Hum,
How is it not possible?
The number of spiral arms is irrelevant.
The central blackhole and amount of darkmatter in the halo would affect wither the galaxy is bared or not. The tightness of the spirals are probably connected with the amount of dust and star/supernova production.
I would also note that galaxies rotate in the opposite direction as the spiral arms would indicate.

 

Not all, leading spirals rotate in the inverse direction, like this
http://archives.cnn.com/2002/TECH/space/02/08/oddball.galaxy/

But most galaxies are trailing spirals, rotating in the correct way

 

1) Stop making cow sounds.

2) Logic, ie. If U have that part of your brain evolved to understand it.

3) Obviously for U, its a matter of human incomprehendability.

4) How was the halo formed ? How will it result in a bar ? Ignorance is bliss isnt it ?

5) Problably ? There is no relation between suprenova and the arms.

6) Ofcourse they will , its due to the low revolution rate of outer stars compared to centrals.

You are a bookworm, or err, a WebWorm.

You should be dealt with hardliners, for U are so premetive and pathetatic.

 

LOL,

You still haven`t explained how it isn`t possible....

I think there is!
Dust clouds encountering a density wave will condense into star forming regions that produce large short-lived stars that produce supernova. The bright stars outline the location of the density waves; without the bright stars we wouldn’t see any spirals.
Supernovas aid that compression process by sending out shock waves that compress gas and dust.


BTW, the word is `primitive` ...

@Lucas

Tnx,
i wasn`t clear with my answer that most rotate in the `normal` direction...

 

Assume , I am wrong. And please dont read below lines, its of no use to U.

If had superNovae resulted in star formations, we should have got spherical stars clusters. But that set aside, I am amazed how you ignore the fact that there are two prominant arms in every spiral galaxy, I guess its your ego thats blinding U. U r yet to evolve to meet my ...