Starshades: Geoengineering Solutions and Technosignatures in Direct Imaging Phase Curves

Sammanfattning: The stellar luminosity increases as a star evolves which inevitably yields a higher temperature on planets in orbit around the star. It is reasonable to assume that intelligent civilizations would tackle this issue through installing artificial structures that can alter the radiation received by the planet. Such structures, if they exist, are potentially detectable with current or near-future technology. I have created a mathematical model that can be used to simulate starshade size as a function of stellar age. With the assumption that life needs a few Gyr to develop, I conclude from habitable zone simulations that stars with masses around $1 M_\odot$ are the most likely to require such solutions. In my project, the structure is assumed to be a circular, reflecting surface -- a so-called starshade -- placed at the inner Lagrange point between the star and the planet. Based on my simulations of the starshade size it can be argued that it can be of similar size to the planet. Through simulations I show that the phase curve of the starshade has a distinct shape and that the technosignature of a starshade is strongly dependent on the starshade size, starshade albedo and the inclination of the star--planet system with respect to the observer. Assuming favorable values on these parameters does, however, point towards starshades being detectable with the next generation telescope technology. This is motivated by my simulations of one of the targets of the Habitable World Observatory.