Armagh Observatory Consolidated Grant 2015 - 2018

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This research combines studies of our Sun, Solar System, and Stars (including the evolution of single and binary systems), and the role played by stars as tracers for our understanding of the wider Universe. Brown dwarfs, thought just a few years ago to be incapable of emitting any significant amounts of radio waves, have been discovered putting out extremely bright beams of radio emission. The study of these apparent 'runts' of the main sequence menagerie could hold vital clues to solving long standing conundrums in conventional coronal astrophysics.A key uncertainty in our knowledge of stars is the role of binarity and the interactions of one star with another during their evolution. In this case, at different times, material from one star can flow onto the other (and sometimes vice versa), and more rarely two stars may collide to produce a single more massive object or sometimes a gigantic explosion called a supernova. Such stellar collisions are called mergers, and they lead to objects with unusual chemical composition which contain a 'fossil' record of the two stars' joint history or (in the case of a supernova) to an object with short-lived properties that can be used to probe the most distant parts of the Universe. A second aspect of our research concerns the measurement of stellar magnetic fields and the impact of magnetic fields on a star's evolution. The reason why some stars are magnetic, and others less so, remains a mystery, and our work aims to provide reliable data with which to compare the different ideas. A third is the origin, evolution and fate of the most massive stars in the Universe. Their evolution is dominated by powerful stellar winds. Do such stars explode disruptively at the end of their lives, or do they ultimately collapse to produce black holes; and, in either case, what is the effect of the stellar wind on neighbouring stars and the nearby star-forming regions? This work will significantly advance our understanding of stars.Our work on the Sun - our nearest Star - has implications not just for understanding stars generally but also for how processes in our Sun's visible atmosphere produce the observed phenomena that ultimately leads to heating of its million-degree Corona and the formation of the Solar Wind. The Sun is a variable star showing a dominant roughly 11-year cycle of magnetic activity between episodes of sunspot maximum and minimum. It is currently observed continuously by a fleet of spacecraft, and our detailed observations from instruments onboard these spacecraft (which cover a very wide range of wavelengths) are designed to improve our understanding of the physics of the Sun's atmosphere and the mechanisms by which it produces occasional massive outbursts of mass and energy. Some of these outbursts have huge power, and can lead not just to the visible appearance of aurorae in the Earth's upper atmosphere but to potentially damaging effects on spacecraft and large-scale power systems on Earth. The variable magnetic activity of the Sun has broad implications for Earth's place in the near-space environment.Lastly, we seek to understand the origin of our planetary system, and the evolution of the small bodies - comets and asteroids (and their debris) - within it. We will study the Trojan asteroids in the orbits of the major planets, for example those of Jupiter and Mars, to test theories of the origin of the Solar System and to understand better how small bodies evolve with time. We will also investigate the detailed processes by which comets decay into meteoroid streams, debris from which may occasionally cross Earth's orbit to produce the well-known phenomenon of a meteor shower - the burning up of small pieces of cometary material in the Earth's atmosphere. Not only are there interesting scientific reasons to study such objects and their interrelationships with each other in the Solar System, but the study of Earth's near-space has important practical benefits.