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Coordinates: Sky map 11h 11m 31.0s, +55° 40′ 27″
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Revision as of 20:26, 23 February 2010

Messier 108
A Hubble Space Telescope image of M108.
Observation data (J2000 epoch)
ConstellationUrsa Major[1]
Right ascension11h 11m 31.0s[2]
Declination+55° 40′ 27″[2]
Redshift699 ± 9 km/s[2]
Distance14.1 Mpc[3]
Apparent magnitude (V)10.7[2]
Characteristics
TypeSB(s)cd[4]
Apparent size (V)8′.7 × 2′.2[2]
Other designations
NGC 3556,[2] PGC 34030,[2] UGC 6225[2]

Messier 108 (also known as NGC 3556) is a barred spiral galaxy in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 or 1782.[5] From the perspective of the Earth, this galaxy is seen almost edge-on.

This galaxy is an isolated[3] member of the Ursa Major Cluster cluster of galaxies in the Virgo supercluster. It has a morphological classification of type SBbc in the de Vaucouleurs system, which means it is a barred spiral galaxy with somewhat loosely wound arms. The maximum angular size of the galaxy in the optical band is 11′.1 × 4′.6, and it is inclined 75° to the line of sight.[4]

This galaxy has an estimated mass of 125 billion times the mass of the Sun and includes about 290 ± 80 globular clusters.[6] Examination of the distribution of neutral hydrogen in this galaxy shows shells of expanding gas extending for several kiloparsecs, known as H1 supershells. These may be driven by bursts of star formation activity, resulting in supernovae explosions. Alternatively they may result from an in fall of gas from outside the galaxy or by radio jets.[7]

Observations with the Chandra X-ray Observatory have identified 83 X-ray sources, including a source located at the nucleus. The brightest of these sources may be an intermediate-mass black hole that is accreting matter. The galaxy is also emitting a diffuse soft X-ray radiation within 10 kpc of the optical galaxy.[3] The spectrum of the X-ray source at the core is consistent with an active galactic nucleus, but an examination with the Spitzer Space Telescope shows no indication of activity. The supermassive black hole at the core has an estimated mass equal to 24 million times the mass of the Sun.[8]

Amateur image of M108

See also

References

  1. ^ R. W. Sinnott, editor (1988). The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer. Sky Publishing Corporation and Cambridge University Press. ISBN 0-933-34651-4. {{cite book}}: |author= has generic name (help)
  2. ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 3556. Retrieved 2007-06-21.
  3. ^ a b c Wang, Q. Daniel (2003). "Chandra Observation of the Edge-on Galaxy NGC 3556 (M 108): Violent Galactic Disk-halo Interaction Revealed". Retrieved 2009-10-15. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. ^ a b Tully, R. B.; Fisher, J. R. (1977). "A new method of determining distances to galaxies". Astronomy and Astrophysics. 54 (3): 661–673. Bibcode:1977A&A....54..661T. {{cite journal}}: |access-date= requires |url= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  5. ^ Kepple, George Robert (1998). The Night Sky Observer's Guide. Vol. 2. Willmann-Bell, Inc. p. 399. ISBN 0-943396-60-3. {{cite book}}: Cite has empty unknown parameter: |1= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ Rhode, Katherine L. (2007). "Global Properties of the Globular Cluster Systems of Four Spiral Galaxies". The Astronomical Journal. 134: 1403–1418. doi:10.1086/521397. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. ^ Gopal-Krishna; Irwin, Judith A. (2000). "Radio jet-blown neutral hydrogen supershells in spiral galaxies?". Astronomy and Astrophysics. pp. 888–894. Bibcode:2000A&A...361..888G. {{cite web}}: |access-date= requires |url= (help); Missing or empty |url= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  8. ^ Satyapal, S. (2008). "Spitzer Uncovers Active Galactic Nuclei Missed by Optical Surveys in Seven Late-Type Galaxies". The Astrophysical Journal. pp. 926–942. doi:10.1086/529014. {{cite web}}: Missing or empty |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)