July 19, 1990

Article at Reuters

Cataclysm may not be the end for some recyclable stars

A pulsar (pink) can be seen at the centre of the galaxy Messier 82

By Wilson da Silva

SYDNEY – A pulsar, the husk of an old exploded star, may get a new burst of life after listlessly spinning through space for a few billion years.

Dr Dick Manchester of the Australia Telescope National Facility told a meeting of the International Astronomical Union in Sydney on Thursday that the 10 or so rapidly spinning pulsars found in the past year could be pulsars risen from the dead.

The pulsars may be billions of years old, but if they have a companion star, matter ejected from it could be dumped on the neutron core of the dead star, rekindling its ancient heart and sparking a burst of new life, he told Reuters.

Manchester said a pulsar was the remains of an ageing star that ran low on fuel and then fell into itself, triggering a cataclysmic explosion that blew much of its mass away.

The core left behind by the explosion continues to compress itself until it is so heavy that a “sugar cube” of the core, if brought to Earth, would weigh 100 million tonnes.

The power of the explosion causes it to spin, and nearby dust is sucked in and crushed at the centre, emitting a strong radio signal that can be picked up by astronomers.

Manchester said a pulsar’s spin should slow as it ages. A young pulsar spins a few hundred times per second, but as they age over millions of years they slow to between 10 times per second to once every few seconds.

If the recycling pulsar theory holds true, pulsars that form part of a two-star system may collect enough material from their partner to begin spinning rapidly again and start “beeping” faster.

Manchester said that although the recycled pulsar theory was first put forward five years ago, it had taken his team’s new discoveries to solidify the case for their existence.

“There are still some astronomers who think they are just very young neutron stars (pulsars) that spin very rapidly,” he said. “But they are now very much in the minority.”