The interacting spiral-galaxy pair MCG-3-25-19 in Hydra, shown from a red-light exposure with an RCA CCD in the EFOSC system at the 3.6-meter telescope of the European Southern Observatory on Cerro La Silla, Chile. North is at the top and east to the left, for direct comparison with a chart or eyepiece view. The image uses a logarithmic intensity transformation to preserve information across a wide dynamic range. The field is 2.9 arcminutes square.
This pair is also known as Arp 252. The MCG designation is from the Morphologicheskii Katalog Galaktik (Morphological Catalog of Galaxies) by B.A. Vorontsov-Valyaminov and coworkers. The first number denotes a declination band on the Palomar Sky Survey (the leading minus is significant!), the second is the sequence number of the sky-survey field within that band, and the final number is a catalog sequence number in that field. This pair, with its spectacular inverted question-mark shape evocative of cosmic mystery, is well fit by numerical simulations of close passages of equal-mass galaxies close to their disk planes. As is common with such strongly interacting galaxies, this pair is a significant far-infrared source, powered by extensive star formation triggered during the interaction.
Last changes: August 1997