EMBARGOED UNTIL: 9:20 AM CST, January 6, 1999 CONTACT: John Biretta Space Telecsope Science Institute, Baltimore, MD (Phone: (410) 338-4917; Internet: biretta@stsci.edu) HUBBLE DETECTS FASTER-THAN-LIGHT MOTION IN GALAXY M87 Astronomers reported today discovering clouds which appear to move many times faster than the speed of light, shooting out from the region of a black hole at the center of the M87 galaxy. These results help explain the nature of distant quasars and ``BL Lac'' objects. ``We see almost a dozen clouds which appear to be moving out from the galaxy's center at between four and six times the speed of light. These are all located in a narrow jet of gas streaming out from the region of the black hole at the galaxy's center," said Dr. John Biretta of the Space Telescope Science Institute. ``We believe this apparent speed translates into an actual velocity just slightly below that of light itself." Biretta and his colleagues Duccio Macchetto, William Sparks, and Eric Perlman announced the results at a meeting of the American Astronomical Society in Austin, Texas. The speeds reported are two to three times faster than the fastest motions previously recorded in M87, the only nearby galaxy to show evidence for superluminal motion. ``This discovery goes a long way towards confirming that radio galaxies, quasars and exotic BL Lac objects are basically the same beast, powered by super massive black holes, and differ only in orientation with respect to the observer," Biretta said. ``Here we have, for the first time, a fairly normal radio galaxy with both excellent evidence for a super-massive black hole, as well as superluminal jet speeds similar to those seen in distant quasars and BL Lac objects." The result also represents a first for the Hubble Space Telescope. ``This is the first time superluminal motion has been seen with any optical telescope, and this discovery was made possible by the extremely fine resolution obtained by Hubble,'' said Macchetto. The measurements compared observations made between 1994 and 1998 with Hubble's Faint Object Camera. In those four years, despite the astonishing speed involved, the clouds traveled only about one-tenth of an arcsecond across the sky -- or about the width of a human hair seen from 100 yards away. ``Current so-called `unified' models hypothesize that radio galaxies, quasars, and BL Lac objects are all the same type of object, but merely seen from different directions. In the case of quasars and BL Lacs, we must be observing from a special direction where the jet is nearly aimed at us. For this orientation, effects related to Einstein's theory of relativity cause the jet to appear very bright, move rapidly, and vary in brightness -- all properties associated with quasars and BL Lacs. And in the more common radio galaxies the jet is hypothesized to be seen side-ways, so it appears relatively undistinguished. ``Our discovery of fast superluminal speeds in M87, a fairly normal radio galaxy, essentially confirms the unified model," said Biretta. The term `superluminal motion' is something of a misnomer. While it accurately describes the speeds measured, scientists still believe the actual speed falls just below the speed of light. ``It's an illusion created by the finite speed of light and rapid motion," Biretta said. ``Our present understanding is that this `superluminal motion' occurs when these clouds move towards Earth at speeds very close to that of light, in this case, more than 98 percent of the speed of light. At these speeds the clouds nearly keep pace with the light they emit as they move towards Earth, so when the light finally reaches us, the motion appears much more rapid than the speed of light. Since the moving clouds travel slightly slower than the speed of light, they do not actually violate Einstein's theory of relativity which sets light as the speed limit." M87 is a faint [9th magnitude] galaxy about 50 million light years distant in the constellation Virgo. Its jet was first discovered in 1918 by an optical astronomer, Heber Curtis, who noticed a very faint wisp of light extending outward from the center of the galaxy. Decades later, radio telescopes were turned to this object, and Curtis's slightly peculiar galaxy turned out to be one of the brightest sources of radio waves in the sky. Such galaxies with strong radio emission are termed ``radio galaxies'' and are now known to be fairly common. The evidence for a super massive black hole at the center of M87 comes from spectroscopic observations made with HST by groups led by Drs. Holland Ford (Johns Hopkins Univ.) and Duccio Macchetto. Macchetto's group found there must be a mass of 3 billion solar masses within 10 light years of the center, which virtually rules out any explanation other than a black hole. The details of how black holes form jets with speeds approaching that of light are still unclear, but current models favor mechanisms where rotation of the accretion disk surrounding the black hole acts to twist-up the magnetic field lines much like a rubber band. This energy is released by flinging material, probably thin clouds of electrons and positrons, down the field lines along the rotation axis, hence forming a narrow jet moving very nearly at the speed of light. This work is made possible by grants from the National Aeronautics and Space Administration and European Space Agency. -===- Color images, high-quality black and white images, video, and other materials are available at our WWW site: http://www.stsci.edu/ftp/science/m87/m87.html More information: John Biretta (410) 338-4917. This work is presented in poster 7.10.