The Monster in the Crab

Gary Poyner gave a fascinating talk on a binary black hole system called OJ+287 which is visible in the constellation Cancer and is one of the largest black holes discovered so far. The larger black hole is accompanied by a smaller one which orbits so close to the primary that it goes through the main black hole’s accretion disc causing major disruption to the system. The luminosity of the system varies significantly – even in a matter of our hours or minutes! Gary has been recording these variations for many years and this has helped scientists understand a lot more about the system both in the short timescales just mentioned but also throughout the system’s 11 year cycle.

Gary is an amateur astronomer working alongside professional scientists who want to understand this system better. In fact, Gary has been working on this for 25 years and has been published in scientific magazines that are usually the exclusive reserve of professionals. That’s quite an achievement!

One thing that Gary brought home really well is the significance of amateur astronomers’ participation in scientific research. He demonstrated by example how we can all make a difference to scientific endeavour by sharing our observations of solar and deep space objects alike.

The main black hole is big – 18 billion solar masses. That’s right, 18 billion times as massive as our Sun. But it’s not the biggest! S5 0014+81 is the largest found so far. This one is 40 billion times the mass of the Sun and Gary told us its diameter is 37 times the distance in Pluto’s orbit. So if I have my sums right that means it is roughly 37 times 23 billion miles across which equals 854 billion miles.

Black holes have been known about for a long time but the first prediction of such objects was longer ago than you might think – John Michell (1724 – 1793) first proposed them. Michell was an extraordinary natural philosopher whose ideas were ground breaking. Here’s an exert from his Wikipedia entry:
John Michell (25 December 1724 – 29 April 1793) was an English clergyman and natural philosopher who provided pioneering insights in a wide range of scientific fields, including astronomy, geology, optics, and gravitation. Considered “one of the greatest unsung scientists of all time”, he was the first person known to propose the existence of black holes in publication, the first to suggest that earthquakes travel in waves, the first to explain how to manufacture artificial magnets, and the first to apply statistics to the study of the cosmos, recognizing that double stars were a product of mutual gravitation. He also invented an apparatus to measure the mass of the Earth. He has been called both the father of seismology and the father of magnetometry.

According to one source, “a few specifics of Michell’s work really do sound like they are ripped from the pages of a twentieth century astronomy textbook.” The American Physical Society (APS) has described Michell as being “so far ahead of his scientific contemporaries that his ideas languished in obscurity, until they were re-invented more than a century later.” The APS states that while “he was one of the most brilliant and original scientists of his time, Michell remains virtually unknown today, in part because he did little to develop and promote his own path-breaking ideas.”

Our thanks to Gary for giving up his time to talk to us.