Triangulum Galaxy
The Triangulum Galaxy is a spiral galaxy 2.73 million light-years (ly) from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC (New General Catalogue) 598. With the D25 isophotal diameter of 18.74 kiloparsecs (61,100 light-years), the Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Andromeda Galaxy and the Milky Way.
| Triangulum Galaxy | |
|---|---|
Galaxy Messier 33 in Triangulum (the Triangulum Galaxy) | |
| Observation data (J2000 epoch) | |
| Pronunciation | /traɪˈæŋɡjʊləm/ |
| Constellation | Triangulum |
| Right ascension | 01h 33m 50.02s |
| Declination | +30° 39′ 36.7″ |
| Redshift | -0.000607 ± 0.000010 |
| Heliocentric radial velocity | -179 ± 3 km/s |
| Galactocentric velocity | -44 ± 6 km/s |
| Distance | 970 kpc (3.2 Mly) |
| Apparent magnitude (V) | 5.72 |
| Characteristics | |
| Type | SA(s)cd |
| Mass | 5×1010 M☉ |
| Number of stars | 40 billion (4×1010) |
| Size | 18.74 kpc (61,120 ly) (diameter; 25.0 mag/arcsec2 B-band isophote) |
| Apparent size (V) | 70.8 × 41.7 arcminutes |
| Other designations | |
| NGC 0598, MCG+05-04-069, UGC 1117, PGC 5818 | |
The galaxy is the smallest spiral galaxy in the Local Group (although the smaller Large and Small Magellanic Clouds may have been spirals before their encounters with the Milky Way), and is believed to be a satellite of the Andromeda Galaxy or on its rebound into the latter due to their interactions, velocities, and proximity to one another in the night sky. It also has an H II nucleus.