NRAO: National Radio Astronomy Observatory

About this Image

Composite image of the nearest Ultraluminous Infrared Galaxy (ULIG), Arp 220. The image shows the optical starlight depicted in green, yellow, and orange, with the neutral atomic hydrogen gas depicted in blue. ULIGs emit more energy in the Infrared than at any other wavelength. This energy arises from a powerful dust-enshrouded starburst, believed to be triggered when two galaxies smash together. The dust is heated by the UV light emitted by the young, hot stars made in the starburst, and re-radiate this energy at infrared wavelengths. The peculiar optical morphology of this system supports the idea that Arp 220 is the result of two galaxies merging into one, and the neutral atomic gas in the outer regions indicates that the galaxies which merged were gas-rich spiral galaxies. There is actually not a hole in the atomic gas distribution; the central gas is absorbed against a bright central radio continum source (not shown) so it is not seen in emission.

Investigator(s):  M. S. Yun and J. E. Hibbard

Alternate Resolutions

Help

This image is available in the following downloadable versions:

• 375 x 332 color JPEG
• 586 x 519 color JPEG
• 1172 x 1037 color TIFF

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.cv.nrao.edu/~jhibbard/a220/
• Up one level for more info on Peculiar galaxies
• For unfamiliar terms, visit the NRAO Radio Astronomy Glossary

Technical Data

Telescope	ALMA
Date of Observation	1994-12-00
Type of Observation	Spectral Line Observations
Wavelength	21 cm
Frequency	1420.4 MHz
Species	HI
Center of Image	RA: 15:34:57.21, Dec: 23:30:9.50 (J2000)
Field of View	0.1000 x 0.1000 degrees
Technical Caption	VLA C+D array observations at 30" resolution. Optical image is a 900 sec R-band observation with the University of Hawai'i 88" telescope obtained in June 1995.



Astronomical database entries for Arp220
• Query NED for images of Arp220
• Query SIMBAD for more Arp220 data

---

SEARCH THE IMAGE GALLERY To search the Image Gallery for other images of Arp220, click the Submit button. Object Name Show Results As: Thumbnails List To search the Image Gallery for similar images, click the Submit button. Category Sub-Category Telescope Mode Show Results As: Any Galaxy AGN Galactic_Sources Solar_System Miscellaneous Telescopes Historical Any Spiral Early-type Dwarf Peculiar Clusters Any GBT VLA VLBA ALMA 12 m 140 ft Any Continuum Spectral Line Thumbnails List For more search options, please use our Advanced Search form.