Messier 82

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**Messier 82**
Observation data (Epoch J2000)
Galaxy	List of galaxies
Image:M82galaxy.jpg M82
Constellation	Ursa Major
Right ascension	09^h 55^m 52.2^s<ref name="ned" />
Declination	+69° 40′ 47″<ref name="ned" />
Redshift	203 ± 4 km/s<ref name="ned" />
Distance	11.5 ± 0.8 Mly (3.5 ± 0.3 Mpc)<ref name="Karachentsevetal2006">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.</ref>
Type	I0<ref name="ned">NASA/IPAC Extragalactic Database. Results for NGC 3034. Retrieved on 2006-10-27.</ref>
Apparent dimensions (V)	11′.2 × 4′.3<ref name="ned" />
Apparent magnitude (V)	9.3<ref name="ned" />
Notable features	Edge on starburst galaxy
Other designations
NGC 3034, UGC 5322, Arp 337, Cigar Galaxy, PGC 28655<ref name="ned" />

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.

Chandra X-ray Observatory image of the Cigar Galaxy

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.<ref>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.</ref> The actual separation is 300⁺³⁰⁰₋₂₀₀

fr:Modèle:± kly.<ref>Separation = sqrt(D_M81² + D_M82² - 2 D_M81 D_M82 Cos(38′.07)) assuming the error direction is about the same for both objects.</ref><ref name="Karachentsevetal2006" />

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.<ref name="Patrunoetal2006">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.</ref>

[edit] Structure

Image:M82s.jpg

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.<ref name="Mayyaetal2005">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.</ref>