The Jet Base of M87


M87, an elliptical galaxy located at the center of the Virgo galaxy cluster, has a jet that is well-studied on arcsec and milli-arcsec scales. Because the jet is bright, the black hole is very massive, and M87 is relatively nearby, this is the best object in which to attempt imaging of the region close to the black hole where the jet is generated and collimated. The figure above is a combined image from five different observations using the VLBA and the Global VLBI Network at 43 GHz. With a high resolution of 430 by 210 microarcseconds (1.3 by 0.64 light-months or at least 100 times better than the Hubble Space Telescope), it reveals that the jet appears brighter at its edge compared to the center, and collimation of the jet is occurring within 100 Schwarzschild radii, which is consistent with previous results by Junor et al. (1999). In addition, the counter-jet may have been detected for the first time. A counter-jet will be important in constraining the geometry of the jet. Proper motions appears to indicate subluminal (below the speed of light) speeds. Student C. Ly acknowledges support through the U.S. NSF Research Experience for Undergraduates (REU) program and NRAO Graduate Research Program.
The above image is an average of five VLBA and Global VLBI observations taken at 43 GHz. The resolution is 430 by 210 microarcseconds or 129 by 63 Schwarzschild radii. The color scale is from 0 to 100 mJy per beam.


Legacy Astronomical Images


NRAO/AUI/NSF does not hold full copyright for this image. Contact the archivist for details.


Legacy Astronomical Image

Object Name


Photo Credit

Chun Ly, UCLA; R Craig Walker, NRAO; William Junor, LANL


Chun Ly, R. Craig Walker, William Junor


Very Long Baseline Array (VLBA)
Global VLBI

Observation Date


Type of Observation





7 mm


45 GHz

Center of Image

RA 12:30:49.420, Dec: 12:23:28.040 (J2000)

Field of View

0.000117 x 0.000200 degrees

Link to journal article


Contact the archivist for a high resolution tif of this image.


Active Galactic Nuclei Series


Radio Galaxies Unit


Legacy Astronomical Images, “The Jet Base of M87,” NRAO Archives, accessed December 3, 2021,