Radio/Optical Composite of M51

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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

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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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