Photos Taken at Chilean Observatory Show How One Galaxy Ate Another

By Dialogo
December 01, 2009

Astronomers with the European Southern Observatory (ESO) in Chile have taken photographs that show how the galaxy Centaurus A ate another, spiral one, between 200 and 700 million years ago, the scientific body announced. The clarity of the new photos is due to the use of the 3.58-meter New Technology Telescope located at La Silla Observatory, in northern Chile, which makes it possible to obtain an even sharper view of the structure of this galaxy, completely free of the dust that obscures it. Centaurus A is the giant elliptical galaxy closest to Earth, at a distance of about 11 million light-years, and is one of the most studied objects in the southern sky, according to the ESO. The well-known British astronomer John Herschel, the author of one of the largest catalogues of the southern skies, detected this galaxy in 1847. Years later, and thanks to observations by the ESA Infrared Space Observatory, a structure 16,500 light-years across was identified, and more recently, the U.S. space agency (NASA)’s Spitzer Space Telescope clarified that the structure is a parallelogram, a giant spiral galaxy, the result of the fusion of two galaxies. “Further analysis of this structure will provide important clues on how the merging process occurred and what has been the role of star formation during it,” Jouni Kainulainen, the principal author of the article published in the journal Astronomy and Astrophysics, maintained in a statement. The activity in the interior of Centaurus A is ongoing, and images captured by the Very Large Telescope, installed in the Cerro Paranal observatory, also in northern Chile, have revealed a black hole at the center of the galaxy with a mass equivalent to 200 million times that of the sun. Unlike the case of the black hole at the center of our galaxy, the Milky Way, the Centaurus black hole is continuously fed by material falling into it, confirming Centaurus as a very active giant galaxy. The ESO is the principal European intergovernmental astronomical organization. It is supported by fourteen countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland, and the United Kingdom.