<p>"Galactic bars develop when stellar orbits in a spiral galaxy become unstable and deviate from a circular path. The tiny elongations
in the stars’ orbits grow and get locked into place, forming a bar. The bar becomes even more pronounced as it collects more and
more stars in elliptical orbits. Eventually, a high fraction of the stars in the galaxy’s inner region join the bar. This process has been
demonstrated repeatedly with computer-based simulations." </p>

<p>Source:
<a href="http://hubblesite.org/hubble_discoveries/science_year_in_review/pdf/2008/barred_spiral_galaxies_and_galactic_evolution.pdf" rel="nofollow noreferrer">http://hubblesite.org/hubble_discoveries/science_year_in_review/pdf/2008/barred_spiral_galaxies_and_galactic_evolution.pdf</a></p>

CC BY-SA 3.0
2017-09-05T20:46:50.287Z
Please provide some more detail than a single quote.
Sir Cumference
CC BY-SA 3.0
2017-09-06T01:04:37.220Z
Are you sure this is up-to-date? It has been known since the 70's that stars in a galaxy have neither purely circular nor purely elliptical orbits.
AtmosphericPrisonEscape
CC BY-SA 3.0
2017-09-10T19:25:21.110Z
found a couple of physics sims here https://www.youtube.com/watch?v=rcQiLAktC-M and https://www.youtube.com/watch?v=lSymkkrbYZI
bandybabboon
CC BY-SA 3.0
2017-09-05T20:16:24.897Z
2017-09-05T20:16:24.897Z
gshepherd
<p>How does the bar in a barred spiral galaxy form? What prevents it from being spirals all the way down like water spiralling down a plughole?</p>

CC BY-SA 3.0
2017-08-30T14:33:17.320Z
For one, spirals in a spiral galaxy are not the same as spirals in draining water. You can't expect the same behavior because the same physics is not governing both concepts.
zephyr
<galaxy><formation><spiral-arms>
How is the bar formed in a Barred-Spiral galaxy?
Beta Decay
# How is the bar formed in a Barred-Spiral galaxy?

(Asked by: username_0 on 2017-08-30)

How does the bar in a barred spiral galaxy form? What prevents it from being spirals all the way down like water spiralling down a plughole?

**Tags:** galaxy, formation, spiral-arms
> **Comments:**
> **username_1**: For one, spirals in a spiral galaxy are not the same as spirals in draining water. You can't expect the same behavior because the same physics is not governing both concepts.  

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## 1 answers

### Answer by username_2 on 2017-09-05. Score: 4

"Galactic bars develop when stellar orbits in a spiral galaxy become unstable and deviate from a circular path. The tiny elongations
in the stars’ orbits grow and get locked into place, forming a bar. The bar becomes even more pronounced as it collects more and
more stars in elliptical orbits. Eventually, a high fraction of the stars in the galaxy’s inner region join the bar. This process has been
demonstrated repeatedly with computer-based simulations."

Source:
<http://hubblesite.org/hubble_discoveries/science_year_in_review/pdf/2008/barred_spiral_galaxies_and_galactic_evolution.pdf>

> **Comments:**
> **username_3**: Please provide some more detail than a single quote.  
> **username_4**: Are you sure this is up-to-date? It has been known since the 70's that stars in a galaxy have neither purely circular nor purely elliptical orbits.  
> **username_5**: found a couple of physics sims here https://www.youtube.com/watch?v=rcQiLAktC-M and https://www.youtube.com/watch?v=lSymkkrbYZI  

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