Atomic Gas in 'The Mice'

A composite image of the optical light (green), warm gas (pinkish white), and cold atomic hydrogen gas (blue) in the well known interacting pair of galaxies known as "The Mice", or NGC 4676. The nickname of this object derives from its optical appearance, specifically the narrow tails emering from oval shaped bodies, reminiscent of two mice . This system is the result of two spiral galaxies which are falling together. As computer simulations demonstrate, the tidal tails are thrown out after the galaxies pass each other once and are pulled together by their mutual gravitational attraction. The tails emerge from the far side of the disks, which is pulled less than the other parts of the galaxy. The tails are, in effect, the material that gets "left behind" as the galaxies fall back together. The atomic hydrogen observations, taken with the VLA in its C- and D-array configurations, show the tidal tails to be rich in cold gas, confirming the gas-rich nature of the progenitor disks. The warm gas, as mapped in the Halpha line emission, is likely heated by the young massive stars in star forming regions. There are numerous such regions distributed all along the tails, which may seed the formation of small stellar systems, and possibly even distinct dwarf galaxies.

VLA C+D array observations with a resolution of 30". Optical image is an B-band image, and both this image and the continuum subtracted Halpha image were obtained with the KPNO 2.1m telescope.

Legacy Astronomical Images

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

Legacy Astronomical Image

NGC4676

J. Hibbard & J. van Gorkom

J. Hibbard, J. van Gorkom

Very Large Array (VLA)

1991-05-13

spectral line

21 cm

1420.4 MHz

HI

RA 12:46:10.760, Dec: 30:43:36.000 (J2000)

0.050000 x 0.083333 degrees

Galaxies Series

Peculiar Unit