NRAO: National Radio Astronomy Observatory

About this Image

A composite image of the optical light (green and yellow) and cold atomic hydrogen gas (blue) in the peculiar galaxy Arp 299, also known as NGC 3690/IC 694. Arp 299 is the result of two spiral galaxies which are in the process of colliding and merging into a single object. The atomic hydrogen observations (shown in blue in the image), taken with the Very Large Array, reveal a tremendous HI tail extending 55,000 light years (180 kiloparsecs) from the main bodies of the merging galaxies (see also this alternative version of these same data). Curiously, the gas tail is displaced from the optical tail (green in the figure), an unexpected and presently unexplained phenomena.

Investigator(s):  J. Hibbard & M. Yun

Alternate Resolutions

Help

This image is available in the following downloadable versions:

• 296 x 422 low resolution color gif

If you would like to obtain a higher resolution version of this image, please contact Pat Smiley.

For More Information

• Read the Journal article
• Visit related website http://www.nrao.edu/~jhibbard/a299/
• Up one level for more info on Peculiar galaxies
• For unfamiliar terms, visit the NRAO Radio Astronomy Glossary

Technical Data

Telescope	VLA
Date of Observation	1995-04-18
Type of Observation	Spectral Line Observations
Wavelength	21 cm
Frequency	1420.4 GHz
Species	HI
Center of Image	RA: 11:25:50.00, Dec: 58:53:28.00 (B1950)
Field of View	0.1450 x 0.2083 degrees
Technical Caption	VLA C+D array observations with a resolution of 20". Optical image is a B-band image obtained with the University of Hawai'i's 88" telescope. A discussion of possible explanations for the optical/gaseous offsets can be found in Hibbard, Vacca & Yun 2000 (AJ, 119, 1130)



Astronomical database entries for Arp299
• Query NED for images of Arp299
• Query SIMBAD for more Arp299 data

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