The Spiral Galaxy NGC 772 and its Unique Spiral Arm

 The Spiral Galaxy NGC 772 and its Unique Spiral Arm

Anthony Micci

5/6/2022

Located over 100 million light years from Earth, NGC 772 stands out almost instantly due to its unique and apparently overdeveloped spiral arm. Many theories have been proposed in an effort to explain this phenomenon, and the leding one currently suggests that tidal interactions between NGC 772  and a nearby companion galaxy has resulted in the formation of this lopsided structure. This isn’t the only unique feature for NGC 772, however. NGC 772 is a spiral galaxy, much like our own Milky Way or the nearby Andromeda Galaxy., but oddly enough, it lacks a bright central bar, which is an immense structure near the center of spiral galaxies that interconnects the inner portions of the spiral arms made up of densely populated areas of stars, gas, and dust. The lack of this structure results in the spiral arms to emerge directly from the heart of the galaxy. It certainly stands out from the rest of the distant galaxies in the field of the image as uniquely shaped.

Below is a photo of this unique and peculiar galaxy:

 

This imaging and outlining of the galaxy’s unique structure was organized by astronomer Halton Arp, with the goal of formulating a catalog for other astronomers of over 300 uniquely and oddly shaped galaxies. Among these are galaxies that have detached segments, long tidal tails of gas and stars, and rings. The observations were taken  at the Gemini North Telescope in Hawaii. The observations of the odd spiral structure earned NGC 772 a spot among all of the other bizarre and strange galaxies that have been discovered to date in Arp’s “Atlas of Peculiar Galaxies”, in which NGC 772 falls under the distinction Arp 78. 

The further study of this galaxy, as it continues to undergo tidal interactions with its neighbor, can help astronomers better understand and predict the results of how our own galaxy and others are shaped by tidal interactions and mergers. 

Sources:

Spiral galaxy NGC 772 features an overdeveloped spiral arm (phys.org)