Messier 82
| Messier 82 | |
|---|---|
A mosaic image taken by the Hubble Telescope of Messier 82, combining exposures taken with four colored filters that capture starlight from visible and infrared wavelengths as well as the light from the glowing hydrogen filaments.
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| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 09h 55m 52.2s |
| Declination | +69° 40′ 47″ |
| Redshift | 203±4 km/s |
| Distance | 11.4-12.4 Mly (3.5-3.8 Mpc) |
| Apparent magnitude (V) | 8.41 |
| Characteristics | |
| Type | I0 |
| Size | ~37,000ly in diameter |
| Apparent size (V) | 11′.2 × 4′.3 |
| Notable features | Edge on starburst galaxy |
| Other designations | |
| NGC 3034, UGC 5322, Arp 337, Cigar Galaxy, PGC 28655, 3C 231 | |
Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy about 12 million light-years away in the constellation Ursa Major. A member of the M81 Group, it is about five times more luminous than the whole Milky Way and has a center one hundred times more luminous than our galaxy's center. The starburst activity is thought to have been triggered by interaction with neighboring galaxy M81. As the closest starburst galaxy to Earth, M82 is the prototypical example of this galaxy type.SN 2014J, a type Ia supernova, was discovered in the galaxy on 21 January 2014. In 2014, in studying M82, scientists discovered the brightest pulsar yet known, designated M82 X-2.
M82 was previously believed to be an irregular galaxy. In 2005, however, two symmetric spiral arms were discovered in near-infrared (NIR) images of M82. The arms were detected by subtracting an axisymmetric exponential disk from the NIR images. Even though the arms were detected in NIR images, they are bluer than the disk. The arms were previously missed due to M82's high disk surface brightness, the nearly edge-on view of this galaxy (~80°), and obscuration by a complex network of dusty filaments in its optical images. These arms emanate from the ends of the NIR bar and can be followed for the length of 3 disc scales. Assuming that the northern part of M82 is nearer to us, as most of the literature does, the observed sense of rotation implies trailing arms.
In 2005, the Hubble Space Telescope revealed 197 young massive clusters in the starburst core. The average mass of these clusters is around 200,000 solar masses, hence the starburst core is a very energetic and high-density environment. Throughout the galaxy's center, young stars are being born 10 times faster than they are inside the entire Milky Way Galaxy.
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