Messier 82
From Wikipedia, the free encyclopedia
| Galaxy | List of galaxies |
|---|---|
M82 |
|
| Observation data (Epoch J2000) |
|
| Constellation | Ursa Major |
| Right ascension | 09h 55m 52.2s[1] |
| Declination | +69° 40′ 47″[1] |
| Redshift | 203 ± 4 km/s[1] |
| Distance | 11.5 ± 0.8 Mly (3.5 ± 0.3 Mpc)[2] |
| Type | I0[1] |
| Apparent dimensions (V) | 11′.2 × 4′.3[1] |
| Apparent magnitude (V) | 9.3[1] |
| Notable features | Edge on starburst galaxy |
| Other designations | |
|
Cigar Galaxy, PGC 28655[1] |
|
Messier 82 (also known as NGC 3034 or the Cigar Galaxy) is a starburst galaxy about 12 million light-years away in the constellation Ursa Major.
Forming a striking pair in small telescopes with nearby M81, M82 is being physically affected by its bigger neighbor. Tidal forces caused by gravity have deformed this galaxy, a process that started roughly 100 million years ago. This interaction has caused star formation to increase 10 fold compared to "normal" galaxies. Ignoring any difference in their respective distances from us, the centers of M81 and M82 are about 130,000 light-years apart.[3] The actual separation is 300+300−200 kly.[4][2]
The Chandra X-ray Observatory detected fluctuating X-ray emissions from a location approximately 600 light-years away from the center of M82. Astronomers have postulated that this fluctuating emission comes from the first known intermediate-mass black hole, of roughly 200 to 5000 solar masses.[5]
[edit] Structure
In 2005, two symmetric spiral arms were discovered in the near-infrared (NIR) images of M82. The arms were detected by subtracting an axisymmetric exponential disk from the NIR images. These arms emanate from the ends of the NIR bar and can be followed for the length of 3 disc scales. Even though the arms were detected in the NIR images, they are bluer than the disk. Assuming that the northern part of M82 is nearer to us, which most literature assumes, the observed sense of rotation implies trailing arms. Due to M82's high disk surface brightness, nearly edge-on orientation with respect to us, and the presence of a complex network of dusty filaments in optical images, the arms were not previously detected.[6]
[edit] External links
- M82, SEDS Messier pages
- M82 at Chandra
- SST: Galaxy on Fire!
- M82 at NASA/IPAC EXTRAGALACTIC DATABASE
- WIKISKY.ORG: SDSS image, M82
[edit] References
- ^ a b c d e f g NASA/IPAC Extragalactic Database. Results for NGC 3034. Retrieved on 2006-10-27.
- ^ a b Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics 49 (1): 3-18.
- ^ Declination separation of 36′.87 and Right Ascension separation of 9′.5 gives via Pythagorean theorem a visual separation of 38′.07; Average distance of 11.65 Mly × sin(38′.07) = 130,000 ly visual separation.
- ^ Separation = sqrt(DM812 + DM822 - 2 DM81 DM82 Cos(38′.07)) assuming the error direction is about the same for both objects.
- ^ Patruno, A.; Portegies Zwart, S.; Dewi, J.; Hopman, C. (2006). "The ultraluminous X-ray source in M82: an intermediate-mass black hole with a giant companion". Monthly Notices of the Royal Astronomical Society: Letters 370 (1): L6-L9.
- ^ Mayya, Y. D.; Carrasco, L.; Luna, A. (2005). "The Discovery of Spiral Arms in the Starburst Galaxy M82". The Astrophysical Journal 628 (1): L33-L36.
