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Animation of orbits as predicted by the density wave theory, which explains the existence of stable spiral arms. Stars move in and out of the spiral arms as they orbit the galaxy. Bertil Lindblad proposed that the arms represent regions of enhanced density (density waves) that rotate more slowly than the galaxy's stars and gas. As gas enters a ...
The Whirlpool Galaxy, also known as Messier 51a (M51a) or NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus. [6] [7] [8] It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. [9]
A spiral galaxy is a type of galaxy characterized by a central bulge of old Population II stars surrounded by a rotating disc of younger Population I stars. A spiral galaxy maintains its spiral arms due to density wave theory.
In spiral galaxies, the spiral arms do have the shape of approximate logarithmic spirals, a pattern that can be theoretically shown to result from a disturbance in a uniformly rotating mass of stars. Like the stars, the spiral arms rotate around the center, but they do so with constant angular velocity .
Since the Andromeda Galaxy is seen close to edge-on, it is difficult to study its spiral structure. Rectified images of the galaxy seem to show a fairly normal spiral galaxy, exhibiting two continuous trailing arms that are separated from each other by a minimum of about 13,000 ly (820 million AU) and that can be followed outward from a ...
Dark sky image with some objects around Pinwheel Galaxy (M 101). The quarter in the lower right shows the tail of Ursa Major with the stars Mizar, Alcor and Alkaid.. The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on, unbarred, and counterclockwise spiral galaxy located 21 million light-years (6.4 megaparsecs) [5] from Earth in the constellation Ursa Major.
Messier 74 (also known as NGC 628 and Phantom Galaxy) is a large spiral galaxy in the equatorial constellation Pisces. [a] It is about 32 million light-years away from Earth. [6] The galaxy contains two clearly defined spiral arms and is therefore used as an archetypal example of a grand design spiral galaxy. [7]
NGC 1300 is a barred spiral galaxy located about 65 million light-years away in the constellation Eridanus.The galaxy is about 110,000 light-years across. It is a member of the Eridanus Cluster, a cluster of 200 galaxies, [3] [4] [5] in a subgroup of 2-4 galaxies in the cluster known as the NGC 1300 Group.