Pick your Galaxy

We are bounded in a nutshell of Infinite space: Blog Post #20, Hubble Galactic Tuning Fork: Pick your Galaxy

Ever since Edwin Hubble proved there were many galaxies instead of just one great one (see http://ay17-rcordova.blogspot.com/2015/10/the-great-debate-or-my-universe-is.html for the full story), observations of deep space have yielded more and more diversity in galaxies, none being exactly alike. But like good, inclined to organizing, humans we are, we developed a solid system of classification that fits for most of the galaxies astronomers observe regularly.

We've been discussing many different types of galaxies, such as elliptical and spiral galaxies, as is the case of Andromeda and the Milky Way, but these in turn can be subdivided even further. According to Hubble's observations, he created a system of galaxy classification that described elliptical, spiral, and irregular galaxies.

Starting with elliptical galaxies, which change from most "circular" to most elliptical, we have:

E0:

E1: 

E2:

E3:

E4:

E5:

E6:

E7:

And now we move on to Spiral Galaxies, starting with:

S0: 

But here, the Spiral Galaxy classification splits off into barred and unbarred spirals. So unbarred Spirals look like: 

Sa:

And they continue becoming more complex by adding to their amount of spirals and curvature,

Sb:

Sc:

And now for the barred Spiral Galaxies, which increase in complexity similar to the trend seen in unbarred spirals.

SBa: 

SBb: 

SBc: 

And finally there is a type of galaxy that fits into no classification: the irregular galaxies:

I: 

Although there are more galaxies that don't precisely fit into any of these classification, astronomers are starting to understand how galactic formation and evolution accounts for most of the shapes of these galaxies, including the irregular ones. Suffice to say, gas accumulates in a lot of ways, but when gas is the size of thousands of light-years, standard shapes start to emerge.

References:

http://www.newscientist.com/data/galleries/howdoesmygalaxygrow/m87cfht.jpg

http://www2.le.ac.uk/departments/physics/research/xroa/images/m87.gif/image_preview

http://www.astroimages.org/ccd/pics/m32-3.jpg

http://freestarcharts.com/images/Articles/Messier/M86_NASA_AURA_STScI.jpg

http://messier.seds.org/Pics/More/m49noao.jpg

https://www.le.ac.uk/ph/faulkes/web/images/m59.jpg

http://www.astronomynotes.com/galaxy/m110.jpg

http://bama.ua.edu/~rbuta/nearirs0/plate014c.jpg

http://www.mhhe.com/physsci/astronomy/fix/student/images/23f06.jpg

https://www.ualberta.ca/~pogosyan/teaching/ASTRO_122/lect23/ngc2997_aat.gif

http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit4/Galaxies/aat058.gif

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/M101_hires_STScI-PRC2006-10a.jpg/1280px-M101_hires_STScI-PRC2006-10a.jpg

http://skyserver.sdss.org/dr1/en/astro/galaxies/images/n1300_SBb.gif

https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Hubble2005-01-barred-spiral-galaxy-NGC1300.jpg/350px-Hubble2005-01-barred-spiral-galaxy-NGC1300.jpg

http://www.stardoctor.org/M109-April2007-RubenKier-fullsize.jpg

http://www.robgendlerastropics.com/NGC4449-HST-GendlerS.jpg