NGC 1316-17, the radio galaxy Fornax A

NGC 1316-17, the radio galaxy Fornax A
AAO image reference AAT 118. « Previous || Next

NGC 1316-17, the radio galaxy Fornax A, ngc1316-17,jpg
Top left is NE. Image width about 17 arc min
Image and text © 2001-2010, Australian Astronomical Observatory, Photograph from AAT plates by David Malin.

NGC 1316-17 are on the outskirts of a nearby cluster of galaxies in the southern constellation of Fornax, at a distance of about 60 million light years. At first glance, the optical image of these galaxies does not seem to be very unusual. However, closer inspection shows that the larger galaxy, the elliptical NGC 1316, has distinct dust lanes in its inner regions, and NGC 1317 is a strangely distorted spiral. The dust lanes strongly suggest that NGC 1316 has recently absorbed a dusty spiral galaxy, and that the merger is not yet complete. The colour picture also hints at faint arcs or shells of stars in the outer parts of the galaxy, another strong indication of recent merger activity. A much deeper picture reveals enormous loops and shell-like structures extending far beyond this photograph, again supporting the merger hypothesis.

If any more evidence were needed, it is provided by radio astronomers, who see Fornax A as one of the strongest and largest sources in the sky, with radio lobes extending over several degrees of sky. However, unlike the faint optical extensions, the radio lobes extend roughly E-W across the sky. There is another southern galaxy with many of these characteristics -- dusty elliptical, faint outer shells and somewhat detached from a cluster of galaxies. This is NGC 5128, Centaurus A, a confimed merger remnant.

Related Images
n1316_d    NGC 1316-17, deep image of Fornax A
AAT 7.      Centaurus A, NGC 5128
AAT 7a.    Centaurus A, NGC 5128 (wide field)
AAT 52.    Detail in the dust lane of NGC 5128
UKS 32.   The field of NGC 5128 (Centaurus A, landscape format)
Constellation of Fornax (external site)

For other details of photographic exposure, search technical table by AAT reference number.

Updated by David Malin, 2011 July 4