Stars are some of the most important objects in the Universe. Even though they make up less than 3% of the matter they make up 100% of the visible matter. They are a major apparatus for studying the universe and its evolution. This includes the remnants left from their deaths and the discarded material from stellar winds during their life.
The research into stellar evolution at the IoA encompasses all aspects of stellar evolution but the main themes currently are binary stars, magnetic fields, stellar winds, supernova progenitors, progenitors of gamma-ray bursts, spectral synthesis of resolved and unresolved stellar populations and asymptotic-giant branch stars. The research is primarily theoretical in nature. Our main code is the novel and versatile Cambridge STARS code to produce stellar models to study the above phenomena. In addition we also have strong links with observational groups around the world for which we provide theoretical input.
Neutron Stars
Neutron stars are what is left behind after the death of massive stars. The collapsed cores of these stars reach incredibly high densities; one tablespoon of material from a neutron star would have a mass of several billion tonnes, or about the mass of Mount Everest. The collision of pairs of neutron stars are important sources of gravitational waves (GWs), and are also thought to produce much of the heavy elements in Universe, such as gold. On 17th August, 2017 the first gravitational wave signal from a pair of colliding neutron stars was detected by the LIGO and Virgo detectors. Two seconds later, a flash of high-energy radiation known as a gamma-ray burst was detected by the Fermi telescope. Over the following days and weeks, the signal was detected by numerous other telescopes across the entire electromagnetic spectrum. This is the first time that astronomers have been able to study the same event with such a wide range of different techniques and represents a new era in astronomy.
Black Holes
Even heavier stars can collapse to form black holes, objects so compact that their gravitational pull traps even light. Black holes are the most extreme gravitational objects in the Universe and understanding their properties pushes our current theories of physics to their limits. We now detect GWs from pairs of colliding black holes on a regular basis. By measuring the properties of these black holes (properties such as their masses, angular momenta, and distances from Earth) we hope to build a better understanding of how massive stars pair up and evolve together in ways that they can eventually collide.