Malin 1
Malin 1 is a giant low surface brightness (LSB) spiral galaxy. It is located 1.19 billion light-years (366 Mpc) away in the constellation Coma Berenices, near the North Galactic Pole. As of February 2015, it is the largest known spiral galaxy, with an approximate diameter of 650,000 light-years (200,000 pc), thus over six times the diameter of our Milky Way. It was discovered by astronomer David Malin in 1986 and is the first LSB galaxy verified to exist. Its high surface brightness central spiral is 30,000 light-years (9,200 pc) across, with a bulge of 10,000 light-years (3,100 pc). The central spiral is a SB0a type barred-spiral.
| Malin 1 | |
|---|---|
Image by the DESI Legacy Imaging Surveys, Data Release 10 | |
| Observation data (J2000.0 epoch) | |
| Constellation | Coma Berenices |
| Right ascension | 12h 36m 59.34697s |
| Declination | +14° 19′ 49.1585″ |
| Redshift | 0.082702±0.000013 |
| Heliocentric radial velocity | 24750±10 km/s |
| Galactocentric velocity | 24707±10 km/s |
| Apparent magnitude (V) | 15.809±0.009 |
| Absolute magnitude (V) | −22.01±0.50 |
| Characteristics | |
| Type | SB0a |
| Mass | ~1012 M☉ |
| Size | 34.11 to 36.39 kpc (111,250 to 118,690 ly) (diameter; D25.0 B-band and 2MASS K-band total isophotes) |
| Apparent size (V) | 0.25′ × 0.23′ |
| Notable features | Surrounded by a H I disk |
| Other designations | |
| PGC 42102, LEDA 42102, VPC 1091, 2MASX J12365934+1419494, Gaia DR2 3932516418935413504 | |
Malin 1 is peculiar in several ways: its diameter alone would make it the largest barred spiral galaxy ever to have been observed.
Malin 1 was found later to be interacting with two other galaxies, Malin 1B and SDSS J123708.91+142253.2. Malin 1B is located 46,000 light-years (14,000 pc) away from the high surface brightness central spiral of Malin 1, which may be responsible for the formation of the galaxy's central bar. Meanwhile, SDSS J123708.91+142253.2 is located within the huge, faint halo of Malin 1 and might have caused the formation of the extended low surface brightness disc through tidal stripping.
Observations by Galaz et al. in April 2014 revealed a detailed view of the spiral structure of Malin 1 in optical bands. The galaxy exhibits giant and very faint spiral arms, with some segments up to 33,000 light-years (10,000 pc) in diameter. Other details, such as possible stellar streams and formation regions, are revealed as well. The same authors also say that Malin 1 is larger than thought, with another estimated diameter of around 750,000 light-years (230,000 pc).