Warwick Astronomy & Astrophysics Consolidated Grant 2023-2026

How do stars, planets and galaxies form? How do they evolve, how do they die? The Astronomy and Astrophysics group at the University of Warwick studies questions such as these through observations on telescopes, both large and small, and through physics-driven computational modelling. The use of optical telescopes in astronomy dates back over 400 years to Galileo, but we are now in a new Galilean era of discovery with the first detection of gravitational waves (GWs) only made in 2015. GWs provide a completely different view of the universe, delving to the heart of the most extreme events known as unimaginably dense stars spiral together, and, in their last moments before merging, rival the power output of the rest of the entire observable universe. GW telescopes can "see" almost everywhere at once, but have the equivalent of very blurred vision. To pinpoint sources, we need to see them electromagnetically (EM), i.e. with optical, radio and x-ray telescopes, but even that is difficult because you have to know where to look first. At Warwick we are working on a telescope called GOTO to do just this. From sites in Europe and Australia, GOTO is designed for breadth of vision and speed, to chase the universe's fastest and most violent events within minutes of their detection. Many less powerful, but longer lasting objects emit GWs much closer to Earth within our own galaxy, the Milky Way. We are starting to find systems from EM observations that will also be detectable as GW sources from space. These are exotic sources: one consists of two stars, each the size of the Earth but 100,000 times more massive, that circle each other in a little over five minutes. We will apply specialist high-speed cameras to their study, mounted on large optical telescopes, to probe how they evolve and important step in understanding how many of them there are, and how they came to be. Gravitational waves have given us new eyes on the universe, but new instruments and techniques do almost the same thing. In 1995 the first exoplanet was found through a particularly sensitive application of an old tool of astronomy called spectroscopy. Since then thousands of planets have been found in a bewildering variety of systems, many very different from our Solar System. At Warwick we have long pursued the discovery of exoplanets using both telescopes on Earth and in space, and will do so in this grant in order to understand processes that can destroy or erode planets when they are close to their host stars. Many known exoplanets are close to their host stars, but that is in part due to how we find them, so another strand of our research aims to push planetary detection to wider orbits, closer to those of our Solar system. Warwick has a strong interest in a new ESA-led space mission called PLATO which will provide a dramatic boost to this work. PLATO has a large field of view to allow it to pick up planets orbiting the brightest stars. These are key targets as they are close by, but above all they allow even more challenging application of spectroscopy, enough to allow us to probe the very composition of the planetary atmospheres. Earth and the other planets of the Solar system formed from a disk of material around the young Sun that lives on as the planets themselves but also "debris" in the form of comets, asteroids and dust. We aim to find evidence for similar structures around other stars, in particular from their dust as it scatters starlight. Such material can survive the several billion year lifetime of the star until just a hot dense remnant called a white dwarf remains. The formation of a white dwarf should "deep clean" the environment close to the star, and yet remarkably we have found many example of the planetary debris, and within our research we aim to find out how this can be. There are many other white dwarfs left from stellar evolution which we will map using a new generation of fibre-fed spectrographs that capture objects, 1000 at a time.