Astrophysics in St Andrews/SUPA

The St Andrews astronomy group is interested in questions of origins: where do galaxies, stars and planets come from, and what fundamental physics explains their formation? We are world leaders in solving intricate mathematical problems in these areas, and we use novel methods such as observations at very high precision and simulations with super-computers. Recently we have joined with other groups across Scotland via the Scottish Universities Physics Alliance (SUPA), and in particular broadened our studies of planet formation via theoretical and experimental work from new team members in Edinburgh and Strathclyde. We study a very wide spread of size scales, from discovering planetary systems around stars a few light years away out to measuring the force of gravity acting on the whole universe. We are especially known for comparing observations and theory of astronomical phenomena, so as to best understand the real universe. For example, we predict how protostars form in molecular clouds and grow and interact, and then observe real clouds to test that young stars have the predicted masses and positions. We have five major themes to our research programme. Theme A involves the search for planets beyond the Solar System and focuses on finding the first planets of mass as low as the Earth's. We use timing of transits, when a planet crosses the face of its star causing a brief darkening, and also gravitational lensing, which exploits Einstein's prediction that a planet drifting across the sightline to a distant background star will bend more of its light towards us. Theme B studies how these extrasolar planets form, in the brief time when a young star is orbited by a remnant disc of gases and rocks. We simulate how this material collects into planets, and check that the basic physics is correct using low-gravity plane flights to experimentally collide rocks in interstellar-like conditions of cold and vacuum. The results are tested by imaging real discs to track how planet systems form and then evolve over billions of years. Theme C examines how the young stars themselves form out of gas clouds, and we are working towards simulations with a billion interacting test particles, to study whether events like supernova explosions trigger the birth of new generations of stars. We also analyse if a star connects by magnetic fields to its disc, and if this affects how fast the star spins and what happens to the material that could form planets. Theme D expands this work to much bigger scales, and we will simulate a whole galaxy of stars, while a survey of 250,000 galaxies will study how their structure emerges. If we know how galaxies form into their characteristic shapes of flat discs, spiral arms and central bulges, we can then look at exotic phenomena such as mass flowing inwards to make a super-massive black hole. The intense light from these black holes has an echo effect as it travels to our telescopes that we also use to study the mass and expansion of the universe as a whole. Theme E wraps up this large-scale picture of the universe by testing Newton's law of gravity - some strange results on how galaxies move could be explained if the law is different on small and large scales. We explore this new idea mathematically and design astronomical observations to test it, ranging from the motion of spacecraft in the Solar System to fluctuations in radiation left over from the Big Bang. We address key questions in the Science Roadmap, especially: what are the laws of physics in extreme conditions? how do galaxies, stars and planets form and evolve? and are we alone in the universe? Our work uses many STFC-funded telescopes at a wide range of wavelengths from radio through visible to X-ray. Our new science projects are building up to use major international projects such as ALMA, eMERLIN, Herschel, JWST, SKA and the KEPLER and PLATO planet-detection missions.