Research Fellows Directory
Dr Jonathan Mackey
Dublin Institute for Advanced Studies
Massive stars, despite being few in number and short-lived, are the main drivers of the evolution of gas in galaxies. They emit strong winds and ionizing radiation, both of which heat the surrounding gas and drive strong outgoing shocks. When they reach the end of their lives they explode as supernovae and/or gamma-ray bursts, driving a blast-wave through nearby gas and enriching their environment with heavy elements. Supernova remnants are important sites for acceleration of high-energy cosmic rays. The gas swept up in old supernova remnants can ultimately fragment into dense clouds that form the next generation of stars and planets. Planets and all life on earth are made from the elements such as carbon that are produced in this cosmic cycle of stellar birth and death.
I use a combination of mathematical models and computer simulations to investigate the winds and radiation emitted by massive stars during their lives, and how their explosions as supernovae return their ashes to interstellar space. By comparing the models with observations from telescopes on earth and in space, we can learn about both the stars and their environments. A good example is Betelgeuse, the 10th brightest star in the sky and brightest star in the constellation Orion. It is a massive star near the end of its life, having evolved to become a red supergiant, and is flying through space at more than 100,000 km/h. Two shells of dust and gas have recently been found surrounding it, and I have developed theories and models to explain these shells and their consequences for Betelgeuse and other red supergiant stars. We found that dense shells of gas could be very common around supergiant stars, and that they dramatically change what we would see when these stars explode as supernovae. It is even possible that future generations of stars could form within these shells of dense gas surrounding old stars.
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