Image of the Day: Stunning Beauty of the Centaurus A Massive Elliptical Galaxy

 

         Centaurus a

 

Centaurus A, also known as NGC 5128, is an odd elliptical galaxy with a supermassive black hole at its heart. It lies about 12 million light-years away in the southern constellation of Centaurus (The Centaur) and has the distinction of being the most powerful radio galaxy in the sky. 

This new image of Centaurus A combines ALMA and near-infrared observations of the massive elliptical radio galaxy. The new ALMA observations, shown in a range of green, yellow and orange colors -the result of the Doppler effect as the gas clouds swirl around. They are the sharpest and most sensitive such observations ever made. 


Astronomers think that the bright nucleus, strong radio emission and jet features of Centaurus A are produced by a central black hole with a mass of about 100 million times that of the Sun. Matter from the dense central parts of the galaxy releases vast amounts of energy as it falls towards the black hole.

This Wide Field Imager (WFI) picture highlights the galaxy’s elliptical nature, which shows up as the elongated shape of the fainter outer parts. The glow that fills much of the picture comes from hundreds of billions of cooler and older stars. Unlike most elliptical galaxies, however, Centaurus A’s smooth shape is disturbed by a broad and patchy band of dark material that obscures the galaxy’s center.

The dark band harbors large amounts of gas, dust and young stars. Bright young star clusters appear at the upper-right and lower-left edges of the band along with the red glow of star-forming clouds of hydrogen, whilst some isolated dust clouds are silhouetted against the stellar background. These features, and the prominent radio emission, are strong evidence that Centaurus A is the result of a merger between two galaxies. The dusty band is probably the mangled remains of a spiral galaxy in the process of being ripped apart by the gravitational pull of the giant elliptical galaxy.

Extending from the galaxy to the upper left corner of the image are two groups of reddish filaments, which are roughly lined up with the huge jets that are prominent in radio images. Both sets of filaments are stellar nurseries, containing hot young stars. Above the left side of the dusty band, you'll sse the inner filaments, lying about 30 000 light-years away of the nucleus.

Further out, around 65 000 light-years away from the galaxy’s nucleus and close to the upper left corner of the image, the outer filaments are visible. There is also possibly a very much fainter trace of a counter jet extending to the lower right.

Centaurus A has been extensively studied at wavelengths ranging from radio all the way to gamma-rays. In particular, radio and X-ray observations have been crucial for studying the interaction between the energetic output of the central supermassive black hole and its surroundings.

The Daily Galaxy via ESO

Image credit: ALMA (ESO/NAOJ/NRAO); ESO/Y. Beletsky

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