This thesis focus on the interaction between M dwarf stellar winds and Galactic cosmic rays and the possible effects on the habitability of exoplanets. We use numerical simulations to describe the... Show moreThis thesis focus on the interaction between M dwarf stellar winds and Galactic cosmic rays and the possible effects on the habitability of exoplanets. We use numerical simulations to describe the stellar winds of M dwarfs using observable constraints, such as the mass-loss rate, X-ray luminosity, and magnetic field strength/flux. Additionally, we use numerical simulations to describe the propagation of Galactic cosmic rays within M dwarf planetary systems. With these simulations, we can calculate the flux of Galactic cosmic rays reaching exoplanet magnetospheres/atmospheres. Measuring cosmic ray fluxes in exoplanet atmospheres is yet not possible, but cosmic rays are an important ingredient in the context of planetary habitability. For this reason, quantifying these fluxes is essential to complete the habitability “puzzle”. Future exoplanet atmosphere observations with space telescopes, such as the JWST and the ARIEL, will enable us to constrain cosmic ray fluxes in exoplanet atmospheres. Show less
Until the 1990s, the only known planets were those in our Solar System. Three decades later, several thousand exoplanets have been discovered orbiting stars other than the Sun, and substantial... Show moreUntil the 1990s, the only known planets were those in our Solar System. Three decades later, several thousand exoplanets have been discovered orbiting stars other than the Sun, and substantial efforts have been made to explore these strange new worlds through spectroscopic analyses of their atmospheres. In particular, high-dispersion spectroscopy has provided robust measurements of these objects, enabling investigations of the significant, outstanding questions of exoplanetary science: What kinds of planets exist beyond our Solar System? Of what are they made? How did they form? Is there life beyond Earth? This dissertation touches upon all of these topics. Chapter 2 details a study to understand the chemical composition of one of the most extreme exoplanets. Chapter 3 investigates the feasibility of studying the different isotopes of titanium in large gaseous exoplanets, which may provide insight into their formation. Chapter 4 presents an attempt to detect young, still-forming planets in an effort to better understand how this process works. Chapter 5 concludes this dissertation with an evaluation of the ability of large future telescopes to detect molecular oxygen in Earth-like exoplanets, which may trace the presence of life. Show less
Dubber, S.; Biller, B.; Bonavita, M.; Allers, K.; Fontanive, C.; Kenworthy, M.A.; ... ; Taylor, W. 2022
This thesis describes the Multi-site All-Sky CAmeRA (MASCARA), which consists of two small robotic telescope designed to detect exoplanets around the brightest stars in the sky. These telescopes... Show moreThis thesis describes the Multi-site All-Sky CAmeRA (MASCARA), which consists of two small robotic telescope designed to detect exoplanets around the brightest stars in the sky. These telescopes search for exoplanets by continuously taking images of the sky and measuring the brightness of stars in these images, searching for the characteristic dimming that occurs when a planet passes in front of the star, blocking some of the starlight. An introduction to exoplanets is provided in chapter 1. The optical and mechanical design of the MASCARA telescopes, as well as the image processing algorithms, are described in chapter 2. The primary and secondary calibration methods used to remove systematic effects from the brightness measurements, as well as the transit search algorithm used, are described in chapter 3. The first planets discovered by MASCARA, two hot Jupiters orbiting the stars HD 201585 and HD 185603, are described in chapters 4 and 5. Show less
The thesis addresses the long-term dynamical evolution of hierarchical multiple systems. First, we consider the evolution of orbits of stars orbiting a supermassive black hole (SBH). We... Show more The thesis addresses the long-term dynamical evolution of hierarchical multiple systems. First, we consider the evolution of orbits of stars orbiting a supermassive black hole (SBH). We study the long-term evolution and compute tidal disruption rates of stars by the SBH. Such disruption events reveal the physics and properties of stars and SBHs. Furthermore, we study the dynamics of planetesimals in the galactic center (GC). When planetesimals are tidally disrupted by the SBH, this can produce a potentially observable flare. We compute the rates of such disruptions, and find rates consistent with observations, suggesting that planetesimals are formed in the GC around stars, similarly to stars in the solar neighbourhood. Subsequently, we consider the long-term evolution of hierarchical quadruple systems. We appy our techniques to provide an explanation for the lack of transiting circumbinary planets around short-period binaries. Lastly, we generalise our methods, and apply them to study the implications of the long-term dynamical evolution of multiplanet systems on hot Jupiters (HJs). We find that the long-term dynamical evolution in multiplanet systems can explain at most a few per cent of the observed HJs, unless the efficiency of tidal dissipation is much higher than is currently believed. Show less
