Messier 100 (also known as NGC 4321 or the Mirror Galaxy) is a grand design intermediate spiral galaxy in the southern part of the mildly northern Coma Berenices It is one of the brightest and largest galaxies in the Virgo Cluster and is approximately 55 million light-years from our galaxy, about 166,000 light-years in diameter. It was discovered by Pierre Méchain in 1781 and 29 days later seen again and entered by Charles Messier in his catalogue “of nebulae and star clusters”. It was one of the first spiral galaxies to be discovered,and was listed as one of fourteen spiral nebulae by Lord William Parsons of Rosse in 1850. NGC 4323 and NGC 4328 are satellite galaxies of M100; the former is connected with it by a bridge of luminous matter.
Messier 100 is considered a starburst galaxy with the strongest star formation activity concentrated in its center, within a ring – actually two tightly wound spiral arms attached to a small nuclear bar of radius: one thousand parsecs – where star formation has been taking place for at least 500 million years in separate bursts.
As usual on spiral galaxies of the Virgo Cluster, in the rest of the disk both star formation and neutral hydrogen, of which M100 is deficient compared to isolated spiral galaxies of similar Hubble type, are truncated within the galaxy’s disk, which is caused by interactions with the intracluster medium of Virgo.
Other designations. HOLM 387A, IRAS 12204+1605, NGC 4321, UGC 7450, MCG +03-32-015, PGC 40153, CGCG 099-030 From Wikipedia, the free encyclopedia| Constellation | Coma Berenices |
|---|---|
| Right ascension | 12h 22m 54.8616s |
| Declination | +15° 49′ 17.886″ |
| Redshift | 0.005240 |
| Heliocentric radial velocity | 1,571±1 km/s |
| Distance | 55 Mly |
| Group or cluster | Virgo Cluster |
| Apparent magnitude (V) | 9 |
