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Discovered by Pierre Méchain in 1781.

Messier 95 (M95, NGC 3351) is a beautiful barred spiral galaxy situated inconstellation Leo, and one of the fainter Messier Objects.

Pierre Méchain discoveredM95, together withM96, March 20, 1781. Consequently,Charles Messier included it inhis catalog on March 24, 1781.

M95 is a barred spiral of type SBb, or SB(r)ab according to de Vaucouleurs' classification, with nearly circular arms. Alan Sandage, in theHubble Atlas of Galaxies, calls it a "typical ringed galaxy". Its overall appearance is quite similar toM91 except that M95 has more pronounced spiral structure.

M95 is a member of theLeo I or M96 group,which also contains M96,M105 and a number of fainter galaxies.

Barred spiral galaxy M95 was one of the galaxies in the key project of theHubble Space Telescope for the determination of the Hubble constant: the HST was employed to look forCepheid variables and thereby determine this galaxy's distance. A preliminary result has been obtained and published in 1996-97 by the HSTH0 Key Project Team (paper VII, 1997).Their result, corrected for the semi-recent adjustment of the Cepheidbrightness zero point by ESA's Hipparcos astrometrical satellite, isa distance of 35.5+-3.1 million light years. This is in semi-good agreement with the value of about 41 million light years (after correctionfor Hipparcos results) which had been obtained earlier byNial R. Tanvir for its neighborM96, and implies a distance of all the galaxies in the Leo I group of about 38 million light years.

One supernova has been found in M95 so far:Supernova 2012aw, first designatedPSN J10435372+1140177, was discovered on March 16, 2012 by Paolo Fagotti andAlessandro Dimai of the Italian Supernovae Search Project, and independently by Jure Skvarc (Crni Vrh Observatory, Slovenia) when it was at 15th magnitude. On March 19, 2012 it had reached mag 13.1 and was rapidly rising. It is located 60" west and 115" south of the center of M95, in a spiral arm. Observations with the Swift satellite observatory and the location imply that this may be of type IIP.

NGC Online data for M95

References:

• H0 Key Project materials on M95:
  • The HST Key Project Archives - M95
  • J.A. Grahamet.al., 1997. The Extragalactic Distance Scale Key Project VII. The Discovery of Cepheids in the Leo I Group Galaxy NGC 3351. Astrophysical Journal, Vol. 477, p. 535. [ADS: 1997ApJ...477..535G]

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Christine Kronberg
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Last Modification: March 20, 2012

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