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Messier 104

Spiral Galaxy M104 (NGC 4594), type Sa, in Virgo

Sombrero Galaxy

Right Ascension 12 : 40.0 (h:m)
Declination -11 : 37 (deg:m)
Distance 36000 (kly)
Visual Brightness 8.0 (mag)
Apparent Dimension 9x4 (arc min)

Discovered by Pierre Méchain in 1781.

Messier 104 (M104, NGC 4594) is numerically the first object of the catalog which was not included in Messier's originally published catalog. However, Charles Messier added it by hand to his personal copy on May 11, 1781, and described it as a "very faint nebula." It was Camille Flammarion who found that its position coincided with Herschel's H I.43, which is the Sombrero Galaxy (NGC 4594), and added it to the official Messier list in 1921. This object is also mentioned by Pierre Méchain as his discovery in his letter of May 6, 1783. William Herschel found this object independently on May 9, 1784.

This brilliant galaxy was named the Sombrero Galaxy because of its appearance. According to de Vaucouleurs, we view it from just 6 degrees south of its equatorial plane, which is outlined by a rather thick dark rim of obscuring dust. This dust lane was probably the first discovered, by William Herschel in his great reflector.

This galaxy is of type Sa-Sb, with both a big bright core, and as one can see in shorter exposures, also well-defined spiral arms. It also has an unusually pronounced bulge with an extended and richly populated globular cluster system - several hundred can be counted in long exposures from big telescopes.

Recent very deep photographs from the Australian Astronomical Observatory show that this galaxy has a very extended faint halo.

This galaxy was the first one with a large redshift found, by Vesto M. Slipher at Lowell Observatory in 1912. Its redshift corresponds to a recession velocity of about 1,000 km/sec (it is caused by the Hubble effect, i.e. the cosmic expansion). This was too fast for the Sombrero to be an object in our Milky Way galaxy. Slipher also detected the galaxy's (then the nebula's) rotation.

M104 is the dominating member of a small group of galaxies, the M104 group or NGC 4594 group of galaxies.

  • Historical Observations and Descriptions of M104
  • Hubble Space Telescope images of M104
  • ESO/VLT images of M104
  • More images of M104
  • Amateur images of M104; More amateur images

  • Multispectral Image Collection of M104, SIRTF Multiwavelength Messier Museum
  • SIMBAD Data of M104
  • NED Data of M104 - distances
  • Publications on M104 (NASA ADS)
  • Observing Reports for M104 (IAAC Netastrocatalog)
  • NGC Online data for M104

    Hartmut Frommert
    Christine Kronberg

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    Last Modification: August 30, 2007