NGC 7424
| NGC 7424 | |
|---|---|
|
|
| Observation data (J2000 epoch) | |
| Constellation | Grus |
| Right ascension | 22h 57m 18s |
| Declination | −41° 04′ 14″ |
| Redshift | 0.003132 (939 ± 2 km/s) |
| Distance | 37.5 Mly (11.5 Mpc) |
| Apparent magnitude (V) | 11.0 |
| Characteristics | |
| Type | SAB(rs)cd |
| Apparent size (V) | 9.5 x 8.1 arcmin |
| Notable features | similar to the Milky Way |
| Other designations | |
| PGC 070096 | |
NGC 7424 is a barred spiral galaxy located 37.5 million light-years away in the southern constellation Grus (the Crane). Its size (about 100,000 light-years) makes it similar to our own galaxy, the Milky Way. It is called a "grand design" galaxy because of its well defined spiral arms. One supernova and two ultraluminous X-ray sources have been discovered in NGC 7424.
NGC 7424 is intermediate between normal spirals (SA) and strongly barred galaxies (SB). Other features include the presence of a central ring-like structure and a relatively low core brightness relative to the arms. The redder color of the prominent bar indicates an older population of stars while the bright blue color of the loose arms indicates the presence of ionised hydrogen and clusters of massive young stars. NGC 7424 is listed as a member of the IC 1459 Grus Group of galaxies, but is suspected of being a "field galaxy"; that is, not gravitationally bound to any group.
SN 2001ig was a rare Type IIb supernova discovered by Australian amateur Robert Evans on the outer edge of NGC 7424 on 10 December 2001. Type IIb supernovae (SNe) initially exhibit spectral lines of hydrogen (like typical Type II's), but these disappear after a short time to be replaced by lines of oxygen, calcium and magnesium (like typical Type Ib's and Ic's).
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