Why Do Galaxies Within a Given Type Have a Variety of Shapes?

-- | December 1, 2016

Question: Although there are just a few types of galaxies (spiral, elliptic, irregular) why are there so many different shapes of galaxies? One would think that since the forces of nature are the same everywhere, the shapes should be very similar, the only difference should be the size. Is it because of collisions? — Matt

Answer: Galaxy collisions is one reason why there are a wide variety of shapes of galaxies. Another reason, which is the most important driver for galaxy shape variety, is that galaxies evolve as gravity turns gas and dust into stars. In a way, what you are seeing in the diversity of galaxy shapes is the range of evolutionary states in galaxies. Galaxies within a given type with different shapes tend to be at different stages of evolution, largely driven by the star formation process in these galaxies.

Jeff Mangum

Facebook

Twitter

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
	Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.
	The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."
	AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.