Several Harvard professors in the Astronomy and Physics Departments yesterday expressed skepticism over a black hole sighting which a group of astronomers in California and Arizona announced last week.

Astronomers at the Hale and Kitt Peak National Observatories said Friday they observed a massive black hole with a density millions of times greater than the sun at the center of Galaxy M-87.

Lost in Space

Black holes occur when a neutron or another dense star collapses, and causes an area of violent activity in space exerting such strong gravitational forces that no light rays can emerge. This area then "vanishes out of sight, so to speak," Alastair G.W. Cameron, chairman of the Astronomy Department, said yesterday.

Cameron said these new findings are "the first observational confirmation" of violent activity in a galaxy, but he cautioned the activity may not necessarily result from a black hole.

Steven Weinberg, Higgins Professor Physics, said yesterday that although the findings are "really interesting, there is no direct evidence of a black hole."

Several professors and researchers at the Center for Astrophysics are currently seeking explanations for the violent activity similar to that observed in Galaxy M-87.

Larry L. Smarr, junior fellow at the Center for Astrophysics, is currently using computers to examine gravitational waves that result from two colliding black holes, Weinberg said yesterday.

Riccardo Giacconi, professor of Astronomy, said yesterday he and others have researched a black hole named Cygnus X-1, which has a smaller mass than the alleged black hole observed last week.

Despite the amount of research now taking place, Weinberg said, "Little connection exists between the calculations and what is observed."