M95 is a barred spiral galaxy about 36 million light-years away in the constellation of Leo. It was discovered by Pierre Méchain on March 20, 1781, which was the same night he discovered M96. Four days later, Charles Messier including both items in his catalogue. With an apparent magnitude of +10.3, it's visible in small telescopes. Together with M96 and M105 they form a close group of galaxies that are gravitationally bound. Of these, M96 is the brightest and the largest. The group is known as the Leo I or M96 group of galaxies and contains at least another 21 fainter galaxies. It's one of many groups that lie within the Virgo Supercluster. M105 was not included in the original Messier catalogue but added much later by Helen B. Sawyer Hogg in 1947.
The galaxies are best seen during the months of March, April and May.
The constellation of Leo is relatively bright and large. It contains one first magnitude star, Regulus (α Leo - mag. +1.4), which also happens to be the brightest star in the surrounding region of sky. About 24 degrees east and two degrees north of Regulus is the third brightest constellation star, Denebola (β Leo - mag. +2.1). Just less than half the way along a line connecting these two stars are M95, M96 and M105. The northernmost member of the trio is M105 with M96 located 50 arc minutes south of M105 and M95 positioned 40 arc minutes west of M96.
The three galaxies are among the faintest objects in Messier's catalogue. They are visible from dark locations with large 15x70 or 20x80 binoculars, appearing as faint smudges of light. Each galaxy is of a different type; M95 is a barred spiral galaxy, M96 an intermediate spiral galaxy and M105 an elliptical galaxy. The brightest of the three and easiest to spot is M96. It shines at magnitude +9.6, with an apparent size of 8 x 5 arc minutes. At magnitude +10.3 and spanning 4 x 3 arc minutes, M95 is fainter and smaller than M96. The third member, M105, shines at magnitude +9.8 and spans about 5 arc minutes in diameter.
In medium size telescopes of the order of 150mm (6-inch) or 200mm (8-inch) aperture, M95 appears as an oval patch of diffuse light with a bright core. On nights of good seeing, it's possible to notice the central bar structure and surrounding nebulosity. Also visible in the same low power telescope field of view is M96, with its bright oval shaped core. M105 is the least impressive of the trio and appears as a small faint ball of fuzz.
M95 has a diameter of 46,000 light-years. For comparison, M96 and M105 have diameters of 80,000 and 55,000 light-years respectively. On March 16, 2012 a Type II supernova (SN 2012aw) was discovered in M95. It peaked at magnitude +12.7.
M95 Data Table
|Object Type||Barred Spiral galaxy|
|Distance (light-years)||36 Million|
|RA (J2000)||10h 43m 58s|
|DEC (J2000)||+11d 42m 13s|
|Apparent Size (arc mins)||4.4 x 3.3|
|Number of Stars||40 Billion|
|Notable Feature||M95 is a member of the Leo I or M96 group of galaxies|