NGC 2903
Spiral galaxy in the constellation Leo
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NGC 2903 is an isolated barred spiral galaxy in the equatorial constellation of Leo, positioned about 1.5° due south of Lambda Leonis.[10] It was discovered by German-born astronomer William Herschel, who cataloged it on November 16, 1784. He mistook it as a double nebula, as did subsequent observers, and it wasn't until the nineteenth century that the Third Earl of Rosse resolved into a spiral form.[5] J. L. E. Dreyer assigned it the identifiers 2903 and 2905 in his New General Catalogue; NGC 2905 now designates a luminous knot in the northeastern spiral arm.[11]
| NGC 2903 | |
|---|---|
A natural color picture of NGC 2903 captured in 2026. | |
| Observation data (J2000 epoch) | |
| Constellation | Leo |
| Right ascension | 09h 32m 10.111s[1] |
| Declination | +21° 30′ 02.99″[1] |
| Redshift | 556±1 km/s[2] |
| Distance | 30.4 Mly (9.33 Mpc)[3] |
| Group or cluster | Virgo Supercluster[4] |
| Apparent magnitude (V) | 9.0[5] |
| Characteristics | |
| Type | SBbc[6] or SAB(rs)bc[7] |
| Size | 100,000 ly (diameter) |
| Apparent size (V) | 11.48′ × 5.25′[8] |
| Other designations | |
| UGC 5079, IRAS 09293+2143,[9] PGC 27077[2] | |
This field galaxy[12] is located about 30[3] million light-years away from the Milky Way, and is a member of the Virgo Supercluster.[4] The morphological classification of this galaxy is SBbc,[6] indicating a barred spiral (SB) with moderate to tightly-wound spiral arms (bc). De Vaucouleurs and associates assigned it the class SAB(rs)bc, suggesting a weaker bar structure (SAB) with a partial ring (rs). The bar structure appears stronger in the near infrared band. The galaxy as a whole is inclined by an angle of 60° to the line of sight from the Earth.[7]
72% of the stellar mass is located in the outer disk of the galaxy, and 20% is found in the bar. The bulge adds 5% of the stellar mass, and its star population is generally older.[13] However, the central ~650 pc radius volume of the core is a strong starburst region. The star formation rate here is 0.7 M☉ y−1 and it is being fed by gas inflow along the bar. There is no evidence of an active nucleus.[7]
The irregular dwarf galaxy KKH 51 appears to be a companion, as they have an angular separation of 25′ and nearly the same radial velocity.[14]
