Saturday, November 30, 2013

The Sombrero Galaxy, also known as Messier 104 (M104), is a famous unbarred spiral galaxy located in the southern skies, in the direction of Virgo constellation. It lies at a distance of 29.3 million light years from Earth. The galaxy’s designation in the New General Catalogue is NGC 4594. The Sombrero Galaxy is known for its appearance, similar to that of a Mexican hat, with a bright white core surrounded by thick lanes of dust and a halo of globular clusters and stars, appearing almost edge-on when observed from Earth. Messier 104 has an exceptionally large and prominent central bulge, which contains billions of very old stars that are responsible for the glow of the galaxy’s central region. The dust lanes contain a number of younger, brighter stars. M104 is believed to contain a large black hole at its centre. The central region is quite bright across the electromagnetic spectrum. With an apparent visual magnitude of 8.98, the galaxy can’t be seen without binoculars, but it can easily be found in smaller telescopes. The Sombrero Galaxy can be seen in 7×35 binoculars or a 4-inch telescope. The galaxy’s central bulge can be made out in a medium-sized telescope, and the dust lane is visible in larger telescopes, starting from 10-inch and 12-inch telescopes. To distinguish the galaxy’s bulge from the disk, one needs at least an 8-inch telescope. Images from NASA’s Spitzer Space Telescope have revealed that Messier 104 has a significantly larger and more massive halo surrounding it than previously believed, which suggests that it might really be a giant elliptical galaxy. In 2012, infrared images from Spitzer indicated that the Sombrero Galaxy is really two galaxies in one: a large elliptical galaxy with a thin disk galaxy embedded within. The galaxy’s halo, seen glowing in visible light images, was revealed to be the right mass and size for a large elliptical galaxy. The discovery raised questions over the galaxy’s formation because what would usually be the most likely scenario – the giant elliptical galaxy swallowing the smaller spiral galaxy – does not make sense here because the smaller galaxy’s disk would most likely not have survived the collision. Another theory suggests that a cloud of dust was drawn in by the gravity of the elliptical galaxy, and formed a spinning disk around the galaxy’s centre. The Sombrero Galaxy is believed to be similar to Centaurus A, another elliptical galaxy with an embedded disk inside it, located in Centaurus constellation. Found at

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