Sombrero Galaxy

The Sombrero is a spiral galaxy in the constellation Virgo. In the Messier catalog it bears the number M 104

Discovery

M 104 was discovered on April 9, 1781 by Pierre Méchain, as this indicates in a letter on May 6, 1783. In the same year on 11 May Charles Messier took him into his catalog. Regardless of William Herschel discovered the galaxy on 9 May in 1794.

Location and appearance

M104, also known as NGC 4594, lies in the constellation Virgo in apparent proximity to the Virgo cluster of galaxies. With a distance of 30 million light- years, the Sombrero galaxy, however, is closer to us than a lot of these galaxy clusters and will therefore not be considered as a member of this cluster. The brightness of these spiral galaxy is 8.0 magnitudes. For this spiral galaxy is one of the apparently brightest visible in the night sky and in any small telescope. The apparent expansion is 9 arcmin along the major axis, ie a quarter of the diameter of the moon. This corresponds to a true diameter of about 70,000 light-years. The outdoor living area is also close to a very extensive, faintly luminous halo. The mass of the galaxy is estimated at about 800 billion solar masses. This makes it about twice as large as that of the Andromeda nebula and almost three times as large as that of our Milky Way (according to new research findings, the mass of the Milky Way is estimated to be 1.9 trillion solar masses, which is of the Andromeda nebula to 1.2 trillion solar masses. Thus the above estimate is not quite up to date ).

In the Hubble sequence, this spiral galaxy is classified under the type Sa or Sb. She has an exceptionally large and bright core and has very tightly wound spiral arms. The latter, however, are difficult to detect because the galaxy plane is only slightly inclined to the line of sight, that is, we look practically from the side of this galaxy. The very dark, and heavy dust lane, the umspinnt the galaxy, gives it the typical appearance that is reminiscent of a Mexican sombrero.

M104 has a fairly well populated system of globular clusters, of which several hundred are visible in larger telescopes. The total number is estimated at over 2000, and thus exceeds by far the number of globular clusters of the Milky Way.

1912 Vesto Slipher discovered that the Sombrero for that time shows a very large redshift. The resulting speed at which the galaxy is moving away from us, is about 1000 kilometers per second. This rate is so high that the galaxy travels within about 10 million years ago, a distance equal to the radius of the Milky Way. It was already in 1912 realized that this object can not be a permanent member of the galaxy group (cluster ) of the Milky Way, has been speculated as at that time.

Absorption in the infrared by the Spitzer Space Telescope