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A Tour of the Sombrero Galaxy

written by: •edited by: George Adcock•updated: 2/3/2011

Sombrero? Funny name for a galaxy! But, it depends on how you look at it, or what you look at it with. Take a look at the Sombrero galaxy as it is seen through the telescopic eyes of some of the greatest telescopes on the ground and in space.

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    Welcome To The Sombrero Galaxy

    The Sombrero Galaxy, NGC 4594, or Messier object, M104, probably fits its moniker much better when seen in grainy older images taken from small terrestrial based telescopes as can be seen in the image on the left, below. And, it is easy to see the resemblance in the image in the middle, below, taken in the near infrared by the 2MASS survey (Two-Micron All-Sky Survey).

    But, when seen through the lens of the ESO's VLT (Very Large Telescope) in Chile (below right), we see an image that is more reminiscent of the planet Saturn and its marvelous ring system. In this composite image, the galaxy appears almost edge-on and seems to be immersed in a cloud of stars. The nebulous cloud that surrounds the galaxy is made up of billions of unresolved older stars, along with dust and gas and dotted with thousands of globular clusters.

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    Classic image of the Sombrero galaxySombrero galaxy living up to its name.Sombrero from the VLT
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    The Sombrero galaxy is an Sa/Sb-type galaxy, well defined, tight spiral arms and bulbous nucleus. It is located in the constellation of Virgo, and is part of the Virgo cluster of galaxies. Located approximately 28 million light years from the Milky Way galaxy, it shines at a magnitude of +8.98. The galaxy is about 50,000 light years across, about half the size of our own galaxy, but has a mass of about 800 billion suns, slightly more than the mass of the Milky Way at 580 billion suns.

    Although Messier was aware of the galaxy, or nebula as it was perceived at that time, it was not added to the Messier list officially until1921. Originally documented by Pierre Méchain in 1767, it was also independently discovered again by William Herschel in 1784.

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    Hubble's View Of The Sombrero Galaxy

    The Hubble Space Telescope has provided us with an exceptional view of the galaxy in this enhanced image (below left) revealing the intricate dust lanes that lace the arms of this spiral galaxy. The image on the right shows the detail in the structure of the spiral arms, accented by the dark dust lanes.

    Sombrero galaxy by the Hubble Space Telescope Dust lanes in the arms of Sombrero 

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    Multi-spectral Views Of The Sombrero Galaxy

    In the remarkable composite image below, made with contributions from Hubble in the optical, Spitzer in the infrared, and Chandra in the X-Ray portions of the spectrum, one can see a more detailed structure of the Sombrero galaxy as defined by the different energy bands the telescopes view the cosmos in.Sombrero in X-ray, Visible and Infrared The blue image shows regions of the galaxy bright in X-rays. It emphasizes the bright core, indicative of an active black hole feeding on dust and hot gas distributed throughout the center of the galaxy. It should be noted that even though the black hole at the center of the Sombrero galaxy is one of the most massive discovered (approximately 1 billion solar masses, as compared to 4 million solar masses for the black hole at the center of the Milky Way) it is not very active, generating only a small radio signature. The bright blue dots in the image include objects in the galaxy and other background images.Sombrero in X-rays 

    The green image from Hubble shows the optical wavelengths and it is easily seen how the dust in the arms blocks this light from reaching us. One can also easily see the cloud of stars surrounding the galaxy.Sombrero in optical 

    These bands of cool dust can be seen even more clearly in the orange, infrared image from Spitzer. It also shows the dust distributed in the outer regions enveloping the galaxy.Sombrero in infrared 

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    Sombrero

    Whether you are viewing the Sombrero galaxy for the first time through a small backyard telescope or you are gazing at the fascinating multi-spectral images provided by the largest terrestrial telescopes and space telescopes, you can't help but appreciate the beauty of this jewel in the night sky.

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    Image Credits

    In order of appearance:

    http://www.redorbit.com/images/gallery/messier_objects/m_104__sombrero_galaxy/104/7/index.html

    http://www.astr.ua.edu/gifimages/m104color.gif

    http://www.eso.org/public/images/eso0007a/

    Hubble Heritage Team (AURA/STScI /NASA): http://heritage.stsci.edu/commonpages/infoindex/contactus/contactus.html

    http://chandra.harvard.edu/photo/2007/sombrero/