What Forces Shape Bar-Centered Galaxies?

[physalpha]

Some of galalxies have bar style center.
Very mysterious.
The origin?
The galaxies are SBa, SBb and SBc style.
Spiral galaxies are familiar to us. it seems like hurricane.
What kinds of force act on bar centered galaxies?

 

[physalpha]

Are there any data about the velocity distribution from the center to the edgy, or the density distribution in the Universe, or the spectrum distribution about those galaxies?
The detail stars spectrum of one of that kind of galaxies would be very useful to know the origin, I think. And calculated galaxy mass.

 

[Chronos]

See http://www.sciencedaily.com/releases/2009/01/090121144051.htm, for example. Galactic evolution is an evolving science.