![]() Caption:Interacting galaxies NGC 5394/5395. This image was made by combining three CCD frames, taken at the Kitt Peak 0.9-m telescope in April 1987. By using different filters in front of the monochrome detector, corresponding approximately to the primary colors red, green and blue, it is possible to recreate a true-color picture. Each image was processed to correct for detector sensitivity variations and to remove incorrect regions caused by manufacturing defects and by the arrival of cosmic rays at the telescope. This system (Arp 84, VV 48, K 404) has been known for some time as one of the class of "M51-type" pairs (although it is also in the constellation Canes Venatici, it is a considerable distance from M51 itself, both along the line of sight and in projection on the sky). It comprises the large inclined spiral NGC 5395 and the smaller, open spiral NGC 5394, with a very bright stellar nucleus, to the north-west. It is reasonable to assume that the apparent attachment of the two galaxies has been caused by their interaction. NGC 5394 shows arcs of surprisingly high surface brightness around its nucleus. At a distance of over 110 million light years, the galaxies are approximately 50,000 and 100,000 light years across. It was once claimed that NGC 5395 contains leading spiral arms (that is, arms curving ahead of the direction of rotation), which would be very unusual since almost all (some would say categorically all) spiral galaxies seem to have trailing arms (as displayed when stirring cream into a cup of coffee, for example). This anomaly was, almost regrettably, disproved by better data. Copyright: Credit:National Optical Astronomy Observatories |