No fancy title obscuring the subject of this brilliant lecture from Prof Bob Lambourne – this one did exactly what it said on the tin! And what a tour de force it was too – each element of the talk deserved a lecture by itself! But such is the calibre of speaker that WAS attracts these days.
Stars are born, we learned, in what appear to be knots in the spiral arms of galaxies. And understanding galaxy dynamics is a key part of understanding star birth – there is more going on than meets the eye and our knowledge has grown only through observations in visible light, microwave and infra-red. Star formation takes place in dense molecular clouds by a condensation process. A protostar is formed featuring jets and an accretion disk out of which planets are created.
Once formed, they take their place as main sequence stars on a Hertzsprung-Russell plot, a graph plotting absolute magnitude of stars against spectral types showing the correspondence between temperature and luminosity. And there it stays for millions of years in a state of hydrostatic equilibrium.
But as the star ages, the hydrogen converts to helium, thence to form carbon; large stars go on to form silicon, sulphur, oxygen, nitrogen and ultimately to the most stable atom of the lot, iron. A small to medium sized star eventually collapses to form a planetary nebula around a white dwarf. A large star, on the other hand, dies in a catastrophic explosion that ejects most of its mass – a supernova – leaving either a black hole or a neutron star. A neutron star is the densest and smallest star known to exist in the Universe, sitting amid a pile of debris, a supernova remnant.
We could have listened all evening but had to finish by 10 pm. Judging by the questions Prof Lambourne fielded, there’s plenty more we want to learn – we must have him back!
In the meantime, our next lecture will be on Wednesday, 16th March from Nik Szymanek about Astrophotography. And that’s always interesting!