Messier 95 NGC 3351, Messier 96 NGC 3368, Messier 105, NGC 3384, and NGC 3389 – a first night

It is an almost perfectly symmetric barred spiral galaxy, the core of which is visible to the amateur astronomer as twin spokes surrounded by a wheel or circle. At visual magnitude 9.7, it is a fainter Messier, being 34 million light years distant.

Messier 95 is in the “main body” of the constellation Leo, near I Leonis and k Leonis, only 2/3 of a degree from Messier 96. As in previous cases of the Messier numbering system, Pierre Mechain discovered the nebula with confirmation occurring a week or two, or even a year later by his friend and colleague, Charles Messier. It was the only way to purely confirm scientifically, a discovery as photography was uninvented and even accurate means of telling time and Longitude were in their infancy. If after discovery, Charle Messier could, using the coordinates provided find the nebulae unaided by the discoverer, it was a true discovery. Thus, a scientific science was born. Both galaxies were discovered by Pierre Mechain in 1781, and catalogued by Charles Messier four days after their discovery.

Méchain discovered either 25 or 26 deep-sky objects. His greatest work might have been measuring “the metre” for the revolutionary French metric system. He was installed as astronomer at the Paris Observatory to continue the work. This measurement would become the basis for the unit of length. He encountered numerous difficulties on this project, largely stemming from the effects of the Terrors.

He was arrested after it was suspected his instruments were weapons (how many times was I pulled over by American Border Patrol at the Peace Arch in Blaine, WA with my mobile 8″ Celestron as suspect?), he was interned in Barcelona after war broke out between France and Spain, and his property in Paris was confiscated. He was released from Spain to live in Italy, then returned home in 1795.

A barred spiral of type SBb, its nearly circular arms span 4.4′ x 3.3′ of sky. Its overall appearance is quite similar to that of M 91, except that M 95 has a more pronounced spiral structure. For the astronomer, March, 2012 will forever shine as the month in which a supernova was discovery in the galaxy before dying out.

Messier 95 has a true diameter extending over 70,000 light years, and a luminosity of 10 billion suns. The nucleus of the galaxy is surrounded by a ring-shaped star forming region with a diameter of approximately 2000 light years. M 95 is receding at 420 miles per second.

M 95 is a member of the M 96 subgroup of the Leo I Group. The M 96 Group’s brightest members are M 95, M 96, the giant ellipticals M 105 and NGC 3377, and the lenticular system NGC 3384. The M 96 Group is extremely compact, covering 3° x 1.5° of sky. The larger Leo I Group also includes the M 65 – M 66 Galaxy Group in western Leo.

William Herschel discovered NGC 3384 in 1784. Dreyer describes it in the New General Catalog as “very bright, large, round, westward abruptly much brighter middle, 2nd of 3 (galaxies).”

NGC 3384 is ~35 million light years from Earth, and is a lenticular that seems to have a central bar. The high age of the stars in its central region was confirmed by their color.

NGC 3384 is part of a trio of galaxies that includes the elliptical M 105 and spiral NGC 3389. All of these are a part of the Leo I galaxy group, which also includes M 95 and M 96.

M 105 was discovered by Pierre Mechain in 1781, only few days after he discovered the nearby galaxies M 95 and M 96. But for unknown reasons, M 105 was not included in Charles Messier’s original list, until 1947, when Helen Hogg found a letter by Mechain describing Messier 105. William Herschel had also observed M 105 in 1784, and assigned it the number H I.17.

In telescopes, M 105 appears as a fuzzy ball, only 2′ across, that gets brighter near the center. It is of type E1, and often studied as a typical representative of elliptical galaxies. With a visual magnitude of 9.25, Messier 105 is the brightest of an 8′-wide triangle of galaxies that includes NGC 3384 and NGC 3389. This trio is part of the M 96 Galaxy Group, and its distance is about 32 million light-years. While NGC 3384 is probably a member of the same Leo I group as M 105, NGC 3389 is probably a background object, as it is receding at 1138 km/sec, much faster than M 105 (752 km/sec), or the other members of the Leo I group (450 – 760 km/sec).

M 105 is a giant elliptical galaxy. Its luminosity corresponds to 15 billion suns. Its true diameter is in excess of 35,000 light years. Investigations with the Hubble Space Telescope have revealed that M 105 contains a supermassive central black hole, of about 50 million solar masses.

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