Thursday, March 08, 2007

Centaurus A

This image of Centaurus A , also known as NGC 5128 , is an example of how frontier science can be combined with esthetic aspects.

This galaxy is a most interesting object for the present attempts to understand active galaxies . It is being investigated by means of observations in all spectral regions, from radio via infrared and optical wavelengths to X- and gamma-rays. It is one of the most extensively studied objects in the southern sky.

Centaurus A is one of the foremost examples of a radio-loud active galactic nucleus (AGN) . On images obtained at optical wavelengths, thick dust layers almost completely obscure the galaxy's centre. This structure was first reported by Sir John Herschel in 1847. Until 1949, NGC 5128 was thought to be a strange object in the Milky Way, but it was then identified as a powerful radio galaxy and designated Centaurus A .

The distance is about 10-13 million light-years (3-4 Mpc) and the apparent visual magnitude is about 8, or 5 times too faint to be seen with the unaided eye.

The core of Centaurus A is the smallest known extragalactic radio source, only 10 light-days across. A jet of high energy particles from this centre is observed in radio and X-ray images. The core probably contains a supermassive black hole with a mass of about 100 million solar masses.

Colour image of the two galaxies NGC 5011B (top) and NGC 5011C (bottom blue galaxy). NGC 5011C is a dwarf galaxy located in the Centaurus A group, while its companion on the sky is in fact a galaxy located 12 times further away and belonging to the Centaurus cluster of galaxies.

With this new distance determination, the astronomers also established that NGC 5011C lies 500,000 light-years away from the dominant galaxy in its group, Centaurus A. Centaurus A (NGC 5128) is the nearest giant elliptical galaxy, at a distance of about 13 million light-years. It is currently merging with a spiral companion galaxy. It possesses a very massive black hole at its centre and is a source of strong radio and X-ray emission.

The Giant That Turned Out To Be A Dwarf from European Southern Observatory.
Learning How Galaxies Form by Centauri Dreams
Double-star Systems Cycle Between Big And Small Blasts from SD
Jet Of Molecular Hydrogen Arising From A Forming High-mass Star

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