Messier 95: Barred Spiral Galaxy in Leo

M95 is one of three Messier galaxies in a tight group in Leo, together with M96 and M105. It is the faintest of the three, but its location due east of Regulus makes it straightforward to find.

What it is

M95 is a barred spiral galaxy: a bar of stars runs across its center, with spiral arms starting from its ends. It lies about 33 million light-years away, and its visible disk spans roughly 40,000 light-years, smaller than our Milky Way. We see it nearly face-on.

Around its nucleus is a small ring where stars are forming rapidly, fed by gas that the bar channels inward. This ring shows up as a bright circle of young star clusters in Hubble images. In March 2012 a supernova, SN 2012aw, appeared in one of its arms, the collapse of a massive star.

M95 belongs to the Leo I group, also called the M96 group, a small cluster of galaxies that includes M96, M105 and several fainter galaxies.

When to see it

From about 40°N, M95 is highest around midnight in early March and around 10 p.m. standard time in early April, reaching about 62° above the southern horizon. Its position just north of the celestial equator makes it visible from most of the Southern Hemisphere too, in the northern sky on autumn evenings.

How to find it

Start at Regulus, the bright star at the base of the Sickle in Leo. Move about 9° due east, to a region with no bright stars. M95 is about 8.7° east of Regulus and almost exactly at the same declination, and M96 is about 0.7° farther east. A useful check is 52 Leonis, a 5th-magnitude star about 2.4° north of M96. Sweep at low power until you find two small glows less than a degree apart; the western, fainter one is M95.

What you will see

M95 is a hard binocular target: under a very dark sky, 10×50s may show a faint spot. In a 70–100 mm telescope it is a small, round, dim glow with a slightly brighter center; from the suburbs it is easy to miss. A 200 mm telescope under dark skies shows a brighter core and, with patience, a faint elongation from the bar running through it. The spiral arms need a larger instrument. Filters do not help.

History

Pierre Méchain discovered M95 on March 20, 1781, together with M96. Charles Messier observed both four days later and added them to his catalog. Its central star-forming ring was studied in detail by later telescopes, and the 2012 supernova gave astronomers a close look at the death of a massive star.