| NGC 4818 | |
|---|---|
 NGC 4818 imaged byHubble Space Telescope | |
| Observation data (J2000epoch) | |
| Constellation | Virgo |
| Right ascension | 12h 56m 48.8829s[1] |
| Declination | −08° 31′ 30.906″[1] |
| Redshift | 0.003552 ± 0.000103[1] |
| Heliocentric radial velocity | 1,065 ± 31 km/s[1] |
| Distance | 45.2 ± 14.2Mly (13.9 ± 4.4Mpc)[1] |
| Group orcluster | Virgo II Groups |
| Apparent magnitude (V) | 11.1[2] |
| Characteristics | |
| Type | SAB(rs)ab pec[1] |
| Size | ~56,000 ly (17.3 kpc) (estimated)[1] |
| Apparent size (V) | 4.3′ × 1.5′[1] |
| Other designations | |
| IRAS 12542-0815,MCG -01-33-057,Mrk 9022,PGC 44191[1] | |
NGC 4818 is aspiral galaxy in the constellationVirgo. The galaxy lies about 45 millionlight years away from Earth, which means, given its apparent dimensions, that NGC 4818 is approximately 55,000 light years across.[1] It was discovered byWilliam Herschel on March 3, 1786.[3]
NGC 4818 has an ellipticalbulge with a bright nucleus. The galaxy has a bar which appears about 30 degrees offset from the major axis of the bulge. Some loosely wrappedspiral arms emerge from the bulge. A faint disk with a low contrast broad spiral pattern is seen surrounding the bulge, aligned with the major axis of the elliptical bulge.[4] The spectrum of the nucleus is similar to that of anHII region.[5] The totalstar formation rate is estimated to be 0.7M☉ per year. The total gas mass is estimated to be109.77 M☉ while the total star mass is about1010.2 M☉.[6]
A. M. Garcia considers the galaxy to be a member of the NGC 4699 Group, or LGG 307. Other members of that group includeNGC 4699,NGC 4700,NGC 4722,NGC 4742,NGC 4781,NGC 4790, andNGC 4802.[7] Makarov et al consider the galaxy to be a member of the Messier 104 Group, along withNGC 4802 and theSombrero Galaxy among other members.[8] It is part of aVirgo II Groups, a chain of groups extending from theVirgo Cluster.[9]
