National Astronomical Observatory of Japan



Sombrero Galaxy M104


Supernova Remnant Crab Nebula (M1) Floating in Empty Space

M104 is a galaxy located between the spring constellations Virgo and Corvus. Its galactic disk seen almost exactly edge on, the dust lane along the disk, and a round shape protruding from the disk are distinctive. This shape has been compared to a Mexican wide brimmed hat, a “sombrero,” and so it is sometimes called the “Sombrero Galaxy.” Although this is one of the Messier objects, which are relatively easy to find with even small-aperture telescopes, it seems to be difficult to recognize this distinctive shape with the naked eye.

Complicated Structures

Based on this distinctive shape, M104 was usually classified as a “spiral galaxy” in the galaxy shape classification system (Hubble Sequence). But, recent observations from large-aperture telescopes and infrared rays revealed that the faint halo, which surrounds the central round protrusion, extends out to a very large distance. In addition, within the halo of M104, it was found that there are thousands of globular clusters; usually only hundreds of these exist in spiral galaxies. Based on these features, M104 is now considered to be an elliptical galaxy, but one that has a disk-shaped structure inside. Astronomers will continue observing with very large telescopes and space telescopes, and I am looking forward to finding out the scenario that resulted in these complex structures.

104th Object in the Messier Objects

M104 is the 104th object in the “Messier Catalog,” a list of nebulae, star clusters, and galaxies compiled by the French astronomer Charles Messier (1730 - 1817). Actually, it is said that the catalog which Messier published himself only included up to M103. But later on, his pupil Pierre Mechain (1744 - 1804) discovered the rest of the objects and added them to the catalog as "nebulae." William Herschel (1738 - 1822), a British astronomer, independently discovered these objects by observing with large-aperture telescopes and identified them as “galaxies.”

Text: Tomoko Ono (Public Relations Center, NAOJ)
Translation by: Hiroko Tsuzuki and Ramsey Lundock (NAOJ)

Image Data

ObjectM104 (Sombrero Galaxy)
TelescopeThe Subaru Telescope
Year Photographed2010
CreditNational Astronomical Observatory of Japan


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