X-ray Binaries

When attending any social function that is not related to his work Dr. Paul Roche commented that when asked what he 'does' he usually answers, "I weigh black holes". Whether this fairly unique reply either spurs the small talk to new heights or stops the conversation dead he declined to say, but nowadays most people have at least heard of these black areas of space where light disappears.

Dr. Roche began his scientific career as a geologist and was very interested in the geology of Mars. Since then he has moved into the field of astrophysics. He is heavily involved in a scheme known as the Faulkes Telescope Project which, for a modest fee, aims to allow schools and amateur astronomers have access to two large robotic telescopes over the internet. One of the telescopes is in Hawaii and the other in Australia and it is hoped that both will be operational by the end of next year. Known respectively as FT-N (for north) and FT-S (for south) each telescope will have a mirror 2m in diameter and a CCD camera to record the observations. So far things are progressing well with the Hawaiian telescope enclosure nearly complete and they are hoping to install the telescope inside it sometime in December. You can catch up on developments and take a peek through the northern webcam by visiting their website:


When he can find time in his hectic project schedule, Dr. Roche does spend time studying black holes but his specialist subject, as coined by Mastermind, is neutron stars. More specifically, he studies pairs of stars more formally known as X-ray binary systems where one of the stars is a neutron star.

Unlike a black hole, this type of star has received far less media coverage and many people will be unfamiliar with the term. A neutron star is what is left after a large star has come to the end of its lifetime and run out of fuel to keep it shining. It becomes unstable, collapsing in on itself and then explodes, ejecting most of its mass into the surrounding area of space. The matter that is left is so compacted that only the type of subatomic particles called neutrons can exist; hence the given name.

Neutron stars have only really been studied seriously since the 1960s and are strange objects in their own right. They have the largest known magnetic fields in the Universe and are so dense that a cubic centimetre of their material would weigh on Earth as much as Mount Everest. If you dropped a marshmallow-sized piece of material from a height of 1m it would hit the crust with the energy of a Hiroshima bomb. As they move through space their orbits may encompass hundreds of thousands of kilometres but their paths are incredibly circular, only deviating by fractions of a millimetre. A special type of neutron star, a pulsar, emits a torch-like beam of radio waves. The interval of these pulses is so regular that they are the best timekeepers to date, even better than the atomic clocks in high-tech laboratories.

If you think that all this is a little too esoteric and too far from everyday experience then you should consider one more little gem. When two twirling neutron stars run out of steam they coalesce in milliseconds in a very violent manner. One of the results of the union is the alchemist's dream of gold. So this Christmas when someone receives a glittering piece of gold jewellery take a moment to think about the real nuclear furnace of its birth.