Scientists at St Andrews spent the last decade leading the ground-based discovery of hot Jupiters with WASP. NASA's Kepler/K2 has since delivered large numbers of smaller planets with known radii. We now move from the discovery era into one of characterisation and trying to understand what sort of planets emerge from the formation process in different environments. HARPS-N is enabling us to measure their masses and hence bulk densities. A picture is emerging in which planets smaller than 1.6 Earth radii are predominantly rocky, while bigger ones have lower densities indicating deep water/ice mantles and extended gaseous atmospheres. NASA's Transiting Exoplanet Survey Satellite (TESS) is similar in concept to WASP, using small wide-field telescopes, but in space. It will find many small planets transiting bright stars. We will weigh them with HARPS-N, and learn how easy it is for planets of different sizes to retain oceans and atmospheres under irradiation by their host stars. The ESA CHaracterising ExOPlanets Satellite will measure radii of small planets and phase curves for gas giants. Such phase-curve observations will inform and challenge the work done by our theoretical astrophysicists on the atmospheric structure of exoplanets.
The window into extrasolar planets are their atmospheres. Transition spectra, obtained with the Hubble Space Telescope and from the ground with super-sensitive instruments like FORS2 at the VLT, review the presence of clouds and of gaseous water in some of the extrasolar planets. We perform numerical simulations of exoplanet atmospheres in order to understand what these observations tell us, for example, about the gas chemistry and cloud formation. Researchers in St Andrews have pioneered the cloud formation modelling in exoplanet atmospheres. We simulate the formation of mineral and diamond clouds and their effect on atmospheres in order to understand the chemical diversity of extrasolar planets. Our work links laboratory work, quantum mechanical cluster calculation and large-scale atmosphere modelling in order to predict atmospheres on exoplanets. We are also interested in the occurrence of lightning and other charge-processes in such unusual environments. Lightning has been suggested as a possibility to initiate the chemical steps that led to the emergence of life on Earth.
Simulations of planet-forming disks help to disentangle observations from high-performance facilities like ALMA and and space missions like Herschel. We seek to understand the processes that set the initial conditions for planet formation in planet forming disks. Knowing that the solar system is unique, we aim to understand why so many other planetary systems are different from the solar system.
The long-term evolution of a planet involves an inter-linked set of chemical, physical and geologic processes. On Earth, biology has dramatically altered all of these systems. Research in Earth and Environmental Sciences focuses on the formation of terrestrial planets/atmospheres and their complex evolution through time, guided by the traces these processes leave in the rock record. We use a combination of geochemistry, field geology, spacecraft data, laboratory experiments, and numerical modelling to study how the evolution of life has changed our planet (such as the oxygenation of Earth’s atmosphere, major swings in past climates, etc.) with aims towards uncovering general principles that could affect the evolution and detectability of planets elsewhere in the Galaxy.
Philosophers at the University of St Andrews are excited to work with scientists in the Centre for Exoplanet Science. The collaboration will enable us to give new dimensions to our existing research projects, and also to develop brand-new projects. Our research falls into three main areas:
(1) The ethics of research and exploration, including our responsibilities to protect and/or exploit extraterrestrial resources, and the roles of corporate, national, and international interests in looking beyond Earth. Relevant expertise here includes environmental ethics, our obligations to future generations, and the role of values in science.
(2) The ways in which discovering - or not discovering - simple or complex life elsewhere in the universe may impact our ideas of human value and purpose, in both secular and religious contexts. Relevant expertise here includes population ethics, animal ethics, and the philosophy and anthropology of religion.
(3) Responsible communication and public dialogue around exoplanet science, including both general research into science communication and public engagement, and the distinctive challenges which arise in this area of science. Relevant expertise here includes the ethics and epistemology of trust, distrust, and dialogue; this research also falls under the 'Knowledge, Democracy and Public Discourse' focus of the St Andrews Centre for Ethics, Philosophy and Public Affairs (CEPPA).
StA-CES researchers from the School of Biology study, amongst many topics, gene regulatory networks applying statistical methods like Bayesian networks, and pioneered their use in neuronal and ecological systems. Microbes and microbial communities are evolved in highly parallel experiments (e.g., 200 cultures); exploring their similarities/divergence can address questions such as repeatability of evolution and potential scope of evolutionary trajectories.
StA-CES researchers from the School of Biology develop general theory on Darwinian adaption on the topics of inclusive fitness and multilevel selection, and also tailor general theory to the biology of particular species to facilitate empirical testing. Natural selection explains the appearance of design in the living world, but at what level is this design expected to manifest – gene, individual, society – and what is its function? Social evolution provides a window on this problem, by pitting the interests of genes, individuals and societies against each other. A wide range of biological systems is part of these studies, including viruses, bacteria, protozoa, crustaceans, insects, arachnids, fish, mice and humans. Logic and formal equations of natural selection are applied to nonbiological scenarios. For example, Price's theorem of natural selection was used to formalise the idea of cosmological natural selection (the idea that new universes are birthed in black holes and that a process of selection acting at the level of a multiverse leads individual universes to come better adapted for making black holes), and also the weak anthropic principle. With respect to the CES, the interest is in uncovering universals in the logic of natural selection and social evolution, that may go beyond the particulars of biological life on Earth.