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Messier Index/M99

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Messier 99 (also known as M99 or NGC 4254) is an w:unbarred spiral galaxy approximately 60 million w:light-years away in the w:constellation w:Coma Berenices.

Messier 99
A w:near-infrared image of M99.
Credit: w:2MASS/w:NASA.
Observation data (w:J2000 epoch)
Constellation w:Coma Berenices[1]
Right ascension 12h 18m 49.6s[2]
Declination +14° 24′ 59″[2]
Redshift 2407 ± 3 km/s[2]
Distance 60 Mly[citation needed]
Type SA(s)c[2]
Apparent dimensions (V) 5′.4 × 4′.7[2]
Apparent magnitude (V) 10.4[2]
Other designations
NGC 4254,[2] UGC 7345,[2] PGC 39578,[2] Coma Pinwheel Galaxy,[3] Virgo Cluster Pinwheel[3]

The galaxy has a normal looking arm and an extended arm that is less tightly wound. A bridge of neutral hydrogen gas links NGC 4254 with w:VIRGOHI21. The gravity from the w:dark galaxy w:VIRGOHI21 appears to have distorted M99 and drawn out the gas bridge, as the two galaxy-sized objects have a close encounter, before they go their separate ways. It is expected that the drawn out arm will relax to match the normal arm once the encounter is over. Three supernovae have been observed in this galaxy.

Amateur Image of Messier 99 Courtesy Hunter Wilson


Messier 99 was discovered by w:Pierre Méchain on w:March 17, w:1781. The discovery was then reported to w:Charles Messier, who included the object in the w:Messier Catalogue, which was the first astronomical catalogue of star clusters, nebulae, and galaxies.[4]

Messier 99 was one of the first galaxies in which a spiral pattern was first seen. The spiral pattern was first identified by w:Lord Rosse in the mid-nineteenth century.[4]

External links


  1. R. W. Sinnott, editor (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN 0-933-34651-4. 
  2. a b c d e f g h i "NASA/IPAC Extragalactic Database". Results for NGC 4254. Retrieved 2006-11-25. 
  3. a b "SIMBAD Astronomical Database". Results for NGC 4254. Retrieved 2006-11-25. 
  4. a b K. G. Jones (1991). Messier's Nebulae and Star Clusters (2nd edition ed.). Cambridge: Cambridge University Press. ISBN 0-521-37079-5.