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A Dwarf Galaxy Ravaged by Grand Design
RA 14hr 05m 01.608s Dec +53° 39' 43.95"
4.8' × 4.3'
20 million light years
ESA/Hubble & NASA
June 16, 2014
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ABOUT THIS IMAGE:
The subject of this new Hubble image is NGC 5474, a dwarf galaxy located 21 million light-years away in the constellation of Ursa Major (The Great Bear). This beautiful image was taken with Hubble's Advanced Camera for Surveys (ACS).
The term "dwarf galaxy" may sound diminutive, but don't let that fool you - NGC 5474 contains several billion stars! However, when compared to the Milky Way with its hundreds of billions of stars, NGC 5474 does indeed seem relatively small.
NGC 5474 itself is part of the Messier 101 Group. The brightest galaxy within this group is the well-known spiral Pinwheel Galaxy (also known as Messier 101, g0610a). This galaxy's prominent, well-defined arms classify it as a "grand design galaxy", along with other spirals Messier 81 (g0719a) and Messier 74 (g0741).
Also within this group are Messier 101's galactic neighbors. It is possible that gravitational interactions with these companion galaxies have had some influence on providing Messier 101 with its striking shape. Similar interactions with Messier 101 may have caused the distortions visible in NGC 5474.
Both the Messier 101 Group and our own Local Group reside within the Virgo Supercluster, making NGC 5474 something of a neighbor in galactic terms.
5474 is a peculiar dwarf galaxy in the constellation Ursa Major. It is
one of several companion galaxies of the Pinwheel Galaxy (M101), a grand-design
spiral galaxy. Among the Pinwheel Galaxy's companions, this galaxy is
the closest to the Pinwheel Galaxy itself. The gravitational interaction
between NGC 5474 and the Pinwheel Galaxy have strongly distorted the galaxy.
As a result, the disk is offset relative to the nucleus. The star formation
in this galaxy (as traced by hydrogen spectral line emission) is also
offset from the nucleus. NGC 5474 shows some signs of a spiral structure.
As a result, this galaxy is often classified as a dwarf spiral galaxy,
a relative rare group of dwarf galaxies.