M82

Discovered by Johann Elert Bode in 1774,  Messier 82 (M82, NGC 3034) is a remarkable galaxy of peculiar type in constellation Ursa Major. It is usually classified as irregular, though probably a distorted disk galaxy, and famous for its heavy star-forming activity, thus a prototype member of the class of starbursting galaxies.  Forming a most conspicuous physical pair with its neighbor, M81 (THE showpiece galaxies for many Northern hemispherers), this galaxy is the prototype of an irregular of the second type, i.e. a "disk" irregular. Its core seems to have suffered dramatically from a semi-recent close encounter with M81, being in a heavy starburst and displaying conspicuous dark lanes. This turbulent explosive gas flow is also a strong source of radio noise, discovered by Henbury Brown in 1953. The radio source was first called Ursa Major A (strongest radio source in UMa) and cataloged as 3C 231 in the Third Cambridge Catalogue of Radio Sources.

In the infrared light, M82 is the brightest galaxy in the sky; it exhibits a so-called infrared excess (it is much brighter at infrared wavelengths than in the visible part of the spectrum). This behaviour can also be observed for the companion of M51, NGC 5195, and the peculiar galaxy NGC 5128 (Centaurus A). The visual appearance is that of a silvery sliver, as John Mallas decribed it.

Recently, over 100 freshly-formed (young) globular clusters have been discovered in M82 with the Hubble Space Telescope. Their formation is probably another effect triggered by the encounter with M81. It was estimated that the most recent tidal encounter occurred between about 50 and several 100 million years ago: STScI's most recent number was 600 million years, when the 100-million-year-long period of heavier interaction began.

As a member of the M81 group, M82 is 12 million light years distant.

One confirmed, and two possible supernovae have been reported in M82 so far as of  July 2009.

Image Information  Courtesy of SEDS

Image Details:

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  • Instrument:  TMB Optical 152/1200 triplet apo refractor @ f/8
  • Mount:  AP1200GTOCP3
  • Image Scale:  1.6 arc-seconds per pixel after processing
    Camera: SBIG ST-2000XM with AO8 Adaptive Optics and CFW10 Color Filter Wheel using Custom Scientific LRGB filters 
    Filters & Exposure Times:
    • L:  18 x 5 minutes binned 1 x 1
    • R:  18 x 5 minutes binned 2 x 2
      G:    9 x 5 minutes binned 2 x 2
      B:  15 x 5 minutes binned 2 x 2
    • Multiple Luminance Layering in Photoshop (technique as described by Rob Gendler)
    • Total equivalent unbinned exposure time of 8.5 hours
    Software: Maxim DL/CCD, CCDStack, Adobe Photoshop CS2, RC Astro Gradient X-Terminator
    Location:  C.A.A.S. East Observatory, Little Rock, AR., El. 650ft
    Dates: April 2nd-April 7th, 2011

Wade Van Arsdale
Little Rock, AR., USA
April 26th, 2011