Cygnus X-1, the mysterious object in space that is considered one of the best known candidates to be a black hole, appears to be producing huge quantities of antimatter, astronomers at the National Aeronautics and Space Administration's Jet Propulsion Laboratory have reported.

Antimatter is just like ordinary matter except that the electrical charge of its particles is opposite that of matter. Near Cygnus X-1, there appear to be vast amounts of positrons, the positively charged equivalent of the familiar negatively charged electron.

"Many theoretical models have predicted this effect {of black holes}, but this is the first clear evidence supporting such predictions," said the laboratory's James Ling, who described the findings earlier this month at a conference here.

Cygnus X-1, which is about 7,500 light years from Earth, has been known for years as a powerful source of X-rays. That is why astrophysicists consider it a probable black hole. The evidence indicates that Cygnus X-1 contains a mass equivalent to 10 suns compressed into an infinitely small point. The gravity is so strong within a surrounding sphere about 40 miles in diameter that nothing, not even light, can escape.

Meanwhile, the object is attracting matter from a nearby companion star, causing it to rush toward the black hole and go into orbit in a so-called accretion disk. As some matter falls into the black hole, more replaces it from the companion star. The density of matter spinning around Cygnus X-1 appears to be so great that friction of the particles hitting each other has produced tremendous quantities of energy. The energy excites the atoms in a way that causes them to emit X-rays. It is because of the X-ray intensity that astrophysicists suspect Cygnus X-1 is a black hole.