NEW PLANETS FOUND ORBITING A DISTANT STAR, REPORT CLAIMS

                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, January 9, 1992                   TAG: 9201090290
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A5   EDITION: STATE 
SOURCE: Associated Press
DATELINE: NEW YORK                                LENGTH: Medium
NEW PLANETS FOUND ORBITING A DISTANT STAR, REPORT CLAIMS
Scientists say they have detected at least two planets orbiting a dense star in the Milky Way galaxy, a report one expert called the best evidence yet for a planet-like system outside the solar system.
Combined with a report in July of a planet circling a similar star, the new work suggests "planet-making in our galaxy or in the universe . . . is perhaps even more common than we have thought," said co-author Alexander Wolszczan.
If confirmed, the planets from the two studies would be the first known outside the solar system. Several earlier studies had claimed to find such planets, but some of them have been rebutted and none is widely accepted.
David Black, director of the Lunar and Planetary Institute in Houston, called the new report the strongest evidence so far of a planet-like system outside the solar system. Compared to the study reported last July, "it's going to be much more difficult . . . to concoct alternative explanations" for its evidence, he said.
"It's a credible story they're telling. Time will tell if it holds up," he said.
Princeton University physics professor Joseph Taylor said the new evidence was "very persuasive-looking and the analysis thorough. . . . I think they've really got something interesting there."
The study is presented in today's issue of the journal Nature by Wolszczan, a senior research associate with the National Astronomy and Ionosphere Center at the Arecibo Observatory in Puerto Rico, and Dale A. Frail at the National Radio Astronomy Observatory in Socorro, N.M.
They concluded that at least two planets were orbiting a pulsar that lies about 1,300 light-years from Earth in the direction of the constellation Virgo.
A pulsar is an extremely dense star that sends pulses of energy toward Earth. A light-year is the distance light travels in one year, about 5.9 trillion miles.
Normally a pulsar's bursts are extremely regular. But the new study found that radio-wave pulses from the studied pulsar, which arrive about 161 times a second, showed an irregular pattern.
The pattern suggested the pulsar was repeatedly edging toward Earth and then away, being pulled to and fro by the gravity of orbiting planets, researchers said. This wobble was calculated to be about 1,000 miles wide.
One apparent planet, containing at least 2.8 times the mass of Earth, appeared to orbit the pulsar every 98.2 days at about half the distance between the Earth and sun.
The other planet, with at least 3.4 times Earth's mass, appeared to orbit every 66.6 days at just over one-third the distance between the Earth and sun.
Results also suggested the possibility of a third planet that orbits about once a year, Wolszczan said.
The planets may have a density and composition like Earth's, although there is little evidence on that point, he said. But "life as we know it most certainly does not exist" on them because the pulsar bombards them with "a really vicious mix of gamma rays and X-rays" and particles moving near the speed of light, Wolszczan said.
The pulsar formed at least 1 billion years ago, he said. The planets probably formed much later, and after a companion star that orbited the pulsar disappeared, he said.

by Archana Subramaniam by CNB