3C120 Radio Jet

Minimum credit line: Image courtesy of NRAO/AUI and R.C. Walker(for details, see Image Use Policy).

About this Image

This pseudo color image shows the structure of the 1.66 GHz emission from the radio source 3C120 as measured by the VLBA in June 1994. The resolution is 0.015 by 0.007 arcseconds with the higher resolution in the east-west direction. The radio jet is seen extending from the bright core region, where the energy is presumably generated, to about 0.5 arcseconds, or almost 1000 light years. Other observations with both VLBI and the VLA have shown this source to have emission on scales from significantly less than a light year to well over a million light years. The inner few light years of the jet have long been known to show motions of components at speeds faster than that of light. This is the well known "superluminal motion" seen in many bright, compact radio sources. No violation of relativity is involved, just a projection effect for a source moving near the speed of light almost directly toward the observer. Such motions are good evidence that the jet is relativistic (moving near the speed of light) so they give interesting information about the jet physics. It is not known how far from the central object (black hole by most models) the relativistic motion extends before it slows. This source is a good one to use to address this question because it is relatively close so motions can still be measured with the lower resolutions required to to see the structures far from the center. This image is one of a series made by R. C. Walker and collaborators to look at motions on scales of a few hundred light years.

Investigator(s):  R.C. Walker

Alternate Resolutions Help

This image is available in the following downloadable versions:If you would like to obtain a higher resolution version of this image, please contact Pat Smiley.

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Technical Data

    Telescope VLBA 
    Date of Observation 1994-10-06 
    Type of Observation Continuum Observations 
    Band L 
    Wavelength 20 cm 
    Frequency 1.4 GHz 
    Center of Image RA: 04:33:11.10, Dec: 05:21:15.60 (J2000)  
    Field of View 0.0001 x 0.0002 degrees  
    Technical Caption  

  • Astronomical database entries for 3C120
    • Query NED for images of 3C120
    • Query SIMBAD for more 3C120 data


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