Messier 95

Right Ascension	10 : 44.0 (h:m)
Declination	+11 : 42 (deg:m)
Distance	38000 (kly)
Visual Brightness	9.7 (mag)
Apparent Dimension	4.4x3.3 (arc min)

Discovered by Pierre Méchain in 1781.

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

Pierre Méchain discovered M95, together with M96, March 20, 1781. Consequently, Charles Messier included it in his 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 the Hubble Atlas of Galaxies, calls it a "typical ringed galaxy". Its overall appearance is quite similar to M91 except that M95 has more pronounced spiral structure.

M95 is a member of the Leo 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 the Hubble Space Telescope for the determination of the Hubble constant: the HST was employed to look for Cepheid variables and thereby determine this galaxy's distance. A preliminary result has been obtained and published in 1996-97 by the HST H0 Key Project Team (paper VII, 1997). Their result, corrected for the semi-recent adjustment of the Cepheid brightness zero point by ESA's Hipparcos astrometrical satellite, is a 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 correction for Hipparcos results) which had been obtained earlier by Nial R. Tanvir for its neighbor M96, 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 designated PSN J10435372+1140177, was discovered on March 16, 2012 by Paolo Fagotti and Alessandro 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. Graham et.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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Hartmut Frommert
Christine Kronberg
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Last Modification: March 20, 2012