Second Pair of Taffy Galaxies

The "Taffy" galaxies: This composite image shows the results of a collision between two galaxies, UGC 813 (right) and UGC 816 (left). The optical emission from stars appears in its natural color, 21 cm radio emission from interstellar atomic Hydrogen (HI) gas is shown in blue, and 1.4 GHz radio continuum emission in red. UGC 813 and UGC 816 were normal disk galaxies before they collided face-on at a speed of one million miles per hour about 50 million years ago. The disks of stars and dense clouds of molecular gas passed through each other relatively unharmed and are now separating. Diffuse HI gas clouds cannot interpenetrate and were stopped between the galaxies or thrown out in long tails by tidal forces. Disk magnetic fields are anchored by dense molecular clouds and are being stretched like bands of taffy between the galaxies as they separate. The bridge of magnetic fields and relativistic electrons stripped from the disks by the collision produces the radio continuum emission depicted in red. The wreckage from this "cosmic crash test" contains forensic evidence about both the collision itself and the nature of normal galaxies, through their response to such a collision.

Legacy Astronomical Images

NRAO/AUI/NSF does not hold full copyright for this image. Contact the archivist for details.

Legacy Astronomical Image

UGC813

J. M. Uson (NRAO)

J. J. Condon (NRAO), G. Helou (IPAC), T. H. Jarrett (IPAC)

Very Large Array (VLA)

POSS

2001-07-27

spectral line

RA 1:16:16.540, Dec: 46:44:24.200 (J2000)

0.166667 x 0.166667 degrees

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Galaxies Series

Peculiar Unit