On the 28th February saw the return of Dr Susan Cartwright to update us on Supernovae. She delivered the talk with her usual humour. She explained that in supernovae there is a struggle between pressure and gravity. In the end gravity always wins.
There are two types of Supernovae – type 1 and type 2.
In type 1 the mass of a star, reaches a critical limit of 1.44 solar masses then its core collapses.
A type II supernova occurs in larger stars of around 10 solar masses. After it leaves the main sequence it starts fusing increasingly heavy elements in shells around the core. At some point the energy produced by the fusion process in the core isn’t sufficient to overcome gravity and the core collapses. Hence gravity always wins.
Our star will end its life as a white dwarf, having shed its outer layers spectacularly but relatively quietly as a planetary nebula.
Susan went on to show us the periodic table and point out the elements needed to seed new stars.
She took us on a journey back in time, showing us supernovae going back two thousand years. She told us the Chinese were very good at recording these events. The only trouble was that the records were kept in the Emperor’s palace and each time there was a change of emperor, the successor destroyed the previous one’s possessions!!! It was also very hard to translate the records that did survive, because there are not many people who understand ancient Chinese!!!
We are well overdue for a supernovae event. As for Betelgeuse, she very diplomatically said, those of us with more years to look back on as opposed to looking forward to will hopefully see the star go supernova soon!!!

Marilyn Bentley