NRAO: National Radio Astronomy Observatory

About this Image

Three separate sets of observations are involved in this composite image of the spiral galaxy M51, also known as the "Whirlpool Galaxy". The optical image (depicted by green and yellow colors in the above image) highlights the younger stars, as well as the dust; the latter can be seen as dust lanes in the spiral arms of M51 itself and in obscuring the eastern (left hand) part of its companion, NGC5195. The continuum radio emission (depicted by red in the image) is partly due to thermal emission from HII regions, partly to synchrotron emission from relativistic electrons moving in magnetic fields, delineating areas of high compression (i.e. the dust lanes). The spectral-line observations of neutral atomic hydrogen (depicted by blue) gives us the distribution, as well as the kinematics, of the neutral hydrogen gas.

Investigator(s):  A.H. Rots, J.M. van der Hulst, P.E. Seiden, R.C. Kennicutt, P.C. Crane, A. Bosma, L. Athanassoula, and D.M. Elmegreen

Alternate Resolutions

Help

This image is available in the following downloadable versions:

• 484 x 480 color JPEG
• 908 x 900 color JPEG
• 2100 x 2081 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.nrao.edu/astrores/HIrogues/webGallery/RoguesGallery06.html#roguesm51
• Up one level for more info on Spiral galaxies
• For unfamiliar terms, visit the NRAO Radio Astronomy Glossary

Technical Data

Telescope	VLA
Date of Observation	1983-12-31
Type of Observation	Spectral Line Observations
Wavelength	21 cm
Frequency	1420.4 MHz
Species	HI
Center of Image	RA: 13:27:46.50, Dec: 47:27:9.00
Field of View	0.2833 x 0.2833 degrees
Technical Caption	Optical image is a photographic plate taken in Blue light with the KPNO 4m telescope. The radio continuum image is a 1.4 GHz image from the VLA with 7 arcsec resolution. The 21cm line observations are from combined VLA B-array and D-array observations, shown at a resolution of 8 arcsec.



Astronomical database entries for M51
• Query NED for images of M51
• Query SIMBAD for more M51 data

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