Messier 105
Elliptical galaxy in the constellation Leo
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Messier 105 or M105, also known as NGC 3379, is an elliptical galaxy 36.6[3] million light-years away in the equatorial constellation of Leo. It is the biggest elliptical galaxy in the Messier catalogue that is not in the Virgo cluster.[8] It was discovered by Pierre Méchain in 1781, just a few days after he discovered the nearby galaxies Messier 95 and Messier 96.[a][9] This galaxy is one of a few not object-verified by Messier so omitted in the editions of his Catalogue of his era. It was appended when Helen S. Hogg found a letter by Méchain locating and describing this object which matched those aspects under its first-published name, NGC 3379.[9]
| Messier 105 | |
|---|---|
| |
| Observation data (J2000 epoch) | |
| Constellation | Leo |
| Right ascension | 10h 47m 49.600s[1] |
| Declination | +12° 34′ 53.87″[1] |
| Redshift | 0.003026±0.00000734[2] |
| Heliocentric radial velocity | 908 km/s[3] |
| Distance | 36.6 Mly (11.22 Mpc)[3] |
| Group or cluster | Leo I Group[4] |
| Apparent magnitude (V) | 9.3[5] |
| Characteristics | |
| Type | E1[6] |
| Size | ~67,100 ly (20.57 kpc) (estimated)[2] |
| Apparent size (V) | 5.4′ × 4.8′[2] |
| Other designations | |
| M105, HOLM 212A, NGC 3379, UGC 5902, MCG +02-28-011, PGC 32256, CGCG 066-018[7][2] | |
Messier 105 has a morphological classification of E1,[6] indicating a standard elliptical galaxy with a flattening of 10%. The major axis is aligned along a position angle of 71°. Isophotes of the galaxy are near perfect ellipses, twisting no more than 5° out of alignment, with changes in ellipticity of no more than 0.06. There is no fine structure apparent in the isophotes, such as ripples.[10] Observation of giant stars in the halo indicate there are two general populations: a dominant metal-rich subpopulation and a weaker metal-poor group.[4]
Messier 105 is known to have a supermassive black hole at its core whose mass is estimated to be between 1.4×108 and 2×108 M☉.[11] The galaxy has a weak active galactic nucleus of the LINER type with a spectral class of L2/T2, meaning no broad Hα line and intermediate emission line ratios between a LINER and a H II region.[12] The galaxy also contains a few young stars and stellar clusters, suggesting some elliptical galaxies still form new stars, but very slowly.[13]
This galaxy, along with its companion the barred lenticular galaxy NGC 3384, is surrounded by an enormous ring of neutral hydrogen with a radius of 200 kiloparsecs (650 kilolight-years) and a mass of 1.8×109 M☉ where star formation has been detected.[14] Messier 105 is one of several galaxies within the M96 Group (also known as the Leo I Group), a group of galaxies in the constellation Leo, the other Messier objects of which are M95 and M96.[15][16][17][18] It is one of the richest group of galaxies in the Local Volume, and unlike the Local Group, it is dominated by not one but several galaxies.[19]
