M87 is a giant elliptical galaxy near the center of the
a large cluster of galaxies at a distance of 16 Mpc in the
It is one of the first galaxies discovered to have an
optical "jet", which is visible faintly as it protrudes
through the bright optical emission from the stars
in the galaxy. M87 contains the nearest active galactic
nucleus (AGN) in the northern sky, offering the possibility
of studying an AGN at the highest linear resolution.
At radio wavelengths, AGN often display dramatic jets, with
a bright spot at the nucleus and long-thin trails of emission
emanating from the nucleus, passing through the entire galaxy,
and ending in huge "radio lobes" well outside the galaxy.
The jet in M87 it thought to be powered by a super-massive black hole,
which contains about 3 billion solar masses!
The image shown on the right is the first Space VLBI image of M87.
It used radio telescopes spread across the Earth and one
in space to simulate a telecope with incredible angular
resolution. The Japanese HALCA space craft carrying the VSOP
telescope came into operation in 1997 and has well demonstrated
the potential of Space VLBI. This image reveals that the jet
remains strongly limb-brightened to within 2 mas of the black hole.
Mark Reid, Alice Argon, Lincoln Greenhill, Jim Moran