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> Interacting Galaxies Arp 254 in Libra

Interacting Galaxies Arp 254 in Libra

author: ESO/Novapix

reference: a-gax59-17001

Image Size 300 DPI: 11 * 16 cm

MCG-01-39-003 (bottom right) is a peculiar spiral galaxy, that presents a hook at one side, most probably due to the interaction with its neighbour, the spiral galaxy NGC 5917 (upper right). Both these galaxies are located at similar distances, about 87 million light-years away, towards the constellation of Libra (The Balance). NGC 5917 (also known as Arp 254 and MCG-01-39-002) is about 750 times fainter than can be seen by the unaided eye and is about 40,000 light-years across. It was discovered in 1835 by William Herschel, who strangely enough, seems to have missed its hooked companion, only 2.5 times fainter. As seen at the bottom left of this exceptional VLT image, a still fainter and nameless, but intricately beautiful, barred spiral galaxy looks from a distance the entangled pair, while many 'island universes' perform a cosmic dance in the background. Last year, a star exploded in the vicinity of the hook. The supernova, noted SN 2005cf as it was the 84th found that year, was discovered by astronomers Pugh and Li with the robotic KAIT telescope on 28 May 2005. It appeared to be projected on top of a bridge of matter connecting MCG-01-39-003 with NGC5917. Further analysis with the Whipple Observatory 1.5m Telescope showed this supernova to be of the Ia type and that the material was ejected with velocities up to 15 000 km/s (that is, 54 million kilometres per hour!).The discovery of supernovae in tidal tails connecting interacting galaxies remains quite an exceptional event.

Keywords for this photo:

2006 - ARP 254 - ASTRONOMY - GALAXY - INTERACTING - LIBRA - NGC 5917 - SN 2005cf - SPIRAL GALAXY - STAR - SUPERNOVA - TYPE Ia - VLT -