Galaxies Centaurus

Figure 15. A spectrum indicating the velocity of HCO+ molecules around the central black hole in the galaxy Centaurus A (NGC5128) [29]. Centaurus A is the nearest galaxy containing a supermassive black hole.

Fig. 3.31. X-ray spectrum taken from the XMM-Newton and Chandra X-ray observatories of the inner part of the Centaurus cluster of galaxies, where the metallicity is roughly twice solar, showing the iron L- and K-shell features at energies of 1.2 and 6.8 keV repectively. The curve is a two-component fit to the continuum with temperatures of 0.7 and 1.5 keV. After Sanders and Fabian (2006). Courtesy Andy Fabian.

The oxygen abundances found in the elliptical galaxy NGC 5128 (Centaurus-A) by Walsh et al. (1999) show a mean value of about 8.4, i.e. smaller than the mean value determined for the bright PNe in M31. This result is somewhat difficult to understand for such a massive galaxy, unless the most metal rich stars do not produce observable PNe. This possibility is known as the the AGB manque phenomenon (see e.g. Greggio Renzini 1990), by which intermediate mass stars do not reach the top of the AGB due to intense stellar winds. 

Great Attractor A huge concentration of mass, equivalent to about a million galaxies, beyond the Hydra and Centaurus constellations. Our own Galaxy and others near to it are heading towards the Great Attractor at a rate of about 600 kilometres per second. 

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