The search for stars that don't shine took a giant step forward yesterday with fresh evidence that a star in the contellation Circinus may be a mysterious "black hole".
The evidence comes from the High Energy Astronomy Observatory, a 7,000-pound scientic satellite put into earth orbit a little more than three months ago. An array of six x-ray detectors on the satellite discovered that an invisible star in the center of Circinus (Compass) generating X-rays in periodic bursts that suggest it is a long-sought-after black hole.
"There are very preliminary results but we're not dealing with an ordinary star," Dr.Herbert Friedman of the Naval Research Laboratory said yesterday during a press conference at space agency headquarters. "This evidence gives us more detail than we've ever had on a suspected black hole.
Together with Dr.Dror Sadeh of the University of Tel Aviv, Dr.Friedman made the preliminary analysis of the findings of the satellite's six x-ray detectors.
The star at the center of Cicinus (called Cicirnus X-1) is one of two stars suspected of being black holes by scientists. The other is a star at the center of the constellation Cygnus (the swan) that is called Cygnus X-1.
Black holes have been sought ever since the name was coined in 1968 by Princeton University's Dr. John Wheeler, who pointed out that when a massive star exhausted its nuclear fuel and collapsed it would become so dense that its gravity would not allow its light to escape.
The only evidence of a black hole would be the x-ray bursts it generates as its immense gravity draws gas from space and nearby stars at such speeds that it heats the gas to temperatures of millions of degrees.
What the HEAO statellite found at Circinus X-1 was bursts of X-rays, one 2.5 seconds long and the other just short of 2.5 seconds. The bursts occured just far enough apart so that one burst overlapped the other.
"We see two diferent hot spots on the star," Friedman said, "that appear to have different peaking periods. This makes Circinus a definite candidate for a black hole."
Circling earth 230 miles up and scanning a different piece of the sky every day, the HEAO satellite will pick up Circinus again Feb. 20. Astronomers will then configure the satellite to time its X-rays bursts more precisely.
"We need to say there is more than one periodicty to the bursts, more erratic emission if the bursts".
While no scientist has yet identified a black hole with certainty, almost all astromers are convinced they exist. They were first predicted by 18th-century French astronomer Pierre La Place, and again by the late physicist J.Robert Oppenheimer, when he was at the University of California before World War 11.
SO convinced are some astronomers of the existence of black holes that they believe they fill the sky, forming as often as one every four years as massive stars throughout the galaxies, burning out and collapsing to the sixe of ordinary plants.