Why Is A Light Pulsing In Space?

Astronomers using an automated telescope that scans 10 million stars and galaxies a night have discovered a mysterious pulsing light in the Big Dipper.

It flashes like a slowly rotating searchlight, scientists say.

"It's a mystery," said Los Alamos researcher Jim Wren. "It's definitely a strange object."

It was spotted March 29 by the Robotic Optical Transient Search Experiment at Los Alamos. It brightens, then dims and brightens again in a cycle, Wren said.

Ron Remillard of Massachusetts Institute of Technology was the first to see it. He sent out a request for corroborating observations and received a response from Japan within an hour that scientists there saw it, too.

Remillard theorizes the pulsing may come from a black hole, a dying star with a force of gravity so intense that not even light readily escapes its pull. He said the black hole, perhaps on the fringes of our galaxy, may be sucking dust and gas which heats as it spirals to its death, giving off the pulsing light and X-rays.

He has seen similar phenomena, he said, but with different pulse patterns.

"There's a big mystery out there that's not solved," Remillard said.

The lightweight ROTSE telescope is designed to wheel around at a moment's notice, giving astronomers a view of celestial fireworks as they occur. It's mainly intended to watch for gamma ray bursts, but it will watch for other phenomena when gamma rays aren't keeping it busy.

The telescope, built in 1997 by Los Alamos National Laboratory, Lawrence Livermore National Laboratory and the University of Michigan, is housed here in an 8-foot steel cylinder along with the computer that runs it. The computer is linked to satellites that may signal phenomena like the pulsing light.

It takes 5.5 seconds from a satellite signal until ROTSE, plugged into the Internet, gets the message. The satellite gives only a general area of sky, so ROTSE swings around and starts snapping electronic pictures, rapidly scanning that part of the sky.