Messier 51B, NGC 5195

Right Ascension	13 : 30.0 (h:m)
Declination	+47 : 16 (deg:m)
Distance	37000 (kly)
Visual Brightness	9.6 (mag)
Apparent Dimension	6.4x4.6 (arc min)

Discovered by Pierre Méchain in 1781.

M51B or NGC 5195, the companion of M51, was discovered by Pierre Méchain on March 20, 1781. Charles Messier mentions it in his description of M51 in the final (1781) edition of his original catalog. It was assigned an own number by William Herschel when he cataloged it on May 12, 1787: H I.186.

Because of Messier's description, NGC 5195 is sometimes considered as part of Messier Object 51; then the main galaxy, NGC 5194, is denoted M51A. Independent of this, NGC 5195 is frequently also referred to as M51B, and we include this object under that designation here.

This galaxy has undergone a close encounter with the larger and more massive M51 several million years ago. During this encounter, it has been significantly distorted from an original disk to irregular shape; the encounter has also significantly enhanced the spiral structure of larger M51. It is thought that NGC 5195 has passed M51 roughly along our line of sight and is now behind its large neighbor.

NGC 5195 is the smaller, distorted galaxy in the lower part of our image. This image has been cropped from a larger Isaac Newton Telescope image of both interacting galaxies M51 and NGC 5195. NGC 5195 can be seen in many images of M51.

One supernova has been discovered in NGC 5195 so far: Supernova 1945A was found by Humason in this galaxy on April 8, 1945, 6'W and 4'S of the galaxy's nucleus, and reached mag 14.0.

NGC Online data for M51B (NGC 5195)

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Hartmut Frommert
Christine Kronberg
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Last Modification: April 24, 2013