Spiral Galaxy NGC 7331 in Pegasus: Wide-view | Kitt Peak National Observatory
NGC 7331 is the brightest and closest galaxy in the visual galaxy group that bears its name, the NGC 7331 Group. It is one of 18 galaxies chosen by the HST Extragalactic Distance Scale Key Project to calibrate secondary distance estimators. The project is using the Hubble Space Telescope (HST) to obtain an accurate distance to galaxies via Cepheid variables, with the ultimate goal of using these to measure H0 (a cosmological parameter) to an external accuracy of 10%. It was determined this galaxy is about 40 million light years away (and perhaps 30,000 light years across). In this image, you can see examples of its nearby neighbors—both spiral and elliptical galaxies. Nearby this field (not shown) is another famous group of galaxies known as Stephan's Quintet.
Also known as Caldwell 30, this galaxy is often thought of as a twin to the Milky Way owing to its similar size and spiral structure. However, there are a couple of features of its core that set it apart from our home galaxy. For instance, astronomers have found evidence that the Milky Way has a central bar of stars and dust cutting through its center, a feature common to many spiral galaxies. However, NGC 7331 lacks this feature. Additionally, NGC 7331’s central bulge rotates in the opposite direction to its galactic disk—unusual behavior compared to other galaxies and unlike what we observe in the Milky Way.
This image was taken as part of Advanced Observing Program (AOP) at Kitt Peak Visitor Center during 2014.
Release Date: May 7, 2014
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