ATNF Daily Astronomy Picture

20th of April 2015


Hydrogen streams in the Grus Quartet
by Bärbel Koribalski (CASS)

The Grus Quartet consists of four large spiral galaxies, three of which appear to be close together (NGC 7582, NGC 7590 and NGC 7599), while the nearly face-on starburst galaxy NGC 7552 is located a bit further to the west. A dwarf irregular galaxy lies just north of the starburst galaxy NGC 7582, which features prominent HI tidal tails and debris. The contours show the intensity of neutral hydrogen as measured with the 64-m Parkes Telescope (in blue) as part of the HI Parkes All Sky Survey (HIPASS) and with the Australia Telescope Compact Array (ATCA; in black), overlaid onto an optical image from the Digitised Sky Survey. In this map, the angular resolution achieved with the ATCA is a factor 10 better than with Parkes. (Work by Koribalski, Lutz & Kilborn).

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