Host Stars And Their Effects On Exoplanet Atmospheres

Like planets in our solar system, exoplanets form, evolve, and interact with their host stars in many ways. As exoplanets acquire material and grow to the final size, their atmospheres are subjected to intense UV and X-radiation and high-energy particle bombardment from the young host star. Whether a planet can retain its atmosphere and the conditions for significant mass loss both depend upon the strength of the host star's high-energy radiation and wind, the distance of the exoplanet from its host star, the gravitational potential of the exoplanet, and the initial chemical composition of the exoplanet atmosphere. This introductory overview describes the physical processes responsible for the emission of radiation and acceleration of winds of host stars that together control the environment of an exoplanet, focusing on topics that are critically important for understanding exoplanetary atmospheres but are usually not posed from the perspective of host stars. Accordingly, both host stars and exoplanets are not studied in isolation but are treated as integrated systems. Stellar magnetic fields, which are the energy source for activity phenomena including high-energy radiation and winds, play a critical role in determining whether exoplanets are habitable. This text is primarily for researchers and graduate students who are studying exoplanet atmospheres and habitability, but who may not have a background in the physics and phenomenology of host stars that provide the environment in which exoplanets evolve. It provides a comprehensive overview of this broad topic rather than going deeply into many technical aspects but includes a large list of references to guide those interested in pursuing these questions. Nonspecialists with a scientific background should also find this text a valuable resource for understanding the critical issues of contemporary exoplanet research.

Over the past twenty years, astronomers have identified hundreds of extrasolar planets--planets orbiting stars other than the sun. Recent research in this burgeoning field has made it possible to observe and measure the atmospheres of these exoplanets. This is the first textbook to describe the basic physical processes--including radiative transfer, molecular absorption, and chemical processes--common to all planetary atmospheres, as well as the transit, eclipse, and thermal phase variation observations that are unique to exoplanets. In each chapter, Sara Seager offers a conceptual introduction, examples that combine the relevant physics equations with real data, and exercises. Topics range from foundational knowledge, such as the origin of atmospheric composition and planetary spectra, to more advanced concepts, such as solutions to the radiative transfer equation, polarization, and molecular and condensate opacities. Since planets vary widely in their atmospheric properties, Seager emphasizes the major physical processes that govern all planetary atmospheres. Moving from first principles to cutting-edge research, Exoplanet Atmospheres is an ideal resource for students and researchers in astronomy and earth sciences, one that will help prepare them for the next generation of planetary science. The first textbook to describe exoplanet atmospheres Illustrates concepts using examples grounded in real data Provides a step-by-step guide to understanding the structure and emergent spectrum of a planetary atmosphere Includes exercises for students

This book is a compendium of key scientific questions, challenges, and opportunities across different areas of exoplanetary science. The field is currently experiencing rapid growth, and the book provides a front-row view of the advancements at the cutting-edge of the field. Each chapter contains a short exposition on the most important open questions, challenges, and opportunities in a specific area from the perspective of one or more top experts in the area. It provides a starting point for researchers, experts and non-experts alike, to obtain a quick overview of the forefront of exoplanetary science and a vision for the future of the field. Topics range from observational developments and techniques, including exoplanet detection and characterisation methods and state-of-the-art and future missions, to exoplanet theory and modelling including planet formation, planetary interiors, atmospheres, habitability and the search for life. Key Features Provides a close-up view of the frontiers of exoplanetary science research Summarises key questions, challenges, and opportunities across different areas of the field Written by leading experts in the field Provides a valuable reference for early career researchers Topics span from state-of-the-art and emerging areas to long-term future directions

This PhD thesis details the development of a new 1D ionospheric model to describe the upper atmospheres of extrasolar giant plants. The upper atmospheres of Hot Jupiters are subject to extreme radiation conditions that can result in rapid atmospheric escape. The composition and structure of these planets’ upper atmospheres are affected by high-energy emissions from the host star. The nature of these emissions depends on the stellar type and age, making them important factors in understanding the behaviour of exoplanetary atmospheres.

The past decade has delivered remarkable discoveries in the study of exoplanets. Hand-in-hand with these advances, a theoretical understanding of the myriad of processes that dictate the formation and evolution of planets has matured, spurred on by the avalanche of unexpected discoveries. Appreciation of the factors that make a planet hospitable to life has grown in sophistication, as has understanding of the context for biosignatures, the remotely detectable aspects of a planet's atmosphere or surface that reveal the presence of life. Exoplanet Science Strategy highlights strategic priorities for large, coordinated efforts that will support the scientific goals of the broad exoplanet science community. This report outlines a strategic plan that will answer lingering questions through a combination of large, ambitious community-supported efforts and support for diverse, creative, community-driven investigator research.

This book explores the relations between physical parameters of extrasolar planets and their respective parent stars. Planetary parameters are often directly dependent upon their stellar counterparts. In addition, the star is almost always the only visible component of the system and contains most of the system mass. Consequently, the parent star heavily influences every aspect of planetary physics and astrophysics. Drs. Kaspar von Braun and Tabetha Boyajian use direct methods to characterize exoplanet host starts that minimize the number of assumptions needed to be made in the process. The book provides a background on interferometric techniques for stellar diameter measurements, illustrates the authors' approach on using additional data to fully characterize the stars, provides a comprehensive update on the current state of the field, and examines in detail a number of historically significant and well-studied exoplanetary systems.

In this book, renowned scientists describe the complexity of exoplanetary atmospheres and all of the observational techniques that are employed to probe them. Readers will also find a panoramic description of the atmospheres of the planets within the Solar System, with explanation of considerations especially relevant to exoplanets. Over the past few years, thousands of exoplanets have been discovered orbiting around stars relatively close to the Solar System. Astronomers have revealed how varied these exoplanets are (rocky, icy, giant) and how diverse their architecture can be, confirming science fiction images in several cases and extending beyond the human imagination in others. The natural next step is to study their atmospheres and to understand their chemical composition and the physical processes taking place in their interiors, with the aim of detecting biomarkers. This book will appeal to all who seek a comprehensive, state-of-the-art account of the latest knowledge in the rapidly developing and highly interdisciplinary field of exoplanet research.

In this book an international group of specialists discusses studies of exoplanets subjected to extreme stellar radiation and plasma conditions. It is shown that such studies will help us to understand how terrestrial planets and their atmospheres, including the early Venus, Earth and Mars, evolved during the host star’s active early phase. The book presents an analysis of findings from Hubble Space Telescope observations of transiting exoplanets, as well as applications of advanced numerical models for characterizing the upper atmosphere structure and stellar environments of exoplanets. The authors also address detections of atoms and molecules in the atmosphere of “hot Jupiters” by NASA’s Spitzer telescope. The observational and theoretical investigations and discoveries presented are both timely and important in the context of the next generation of space telescopes. The book is divided into four main parts, grouping chapters on exoplanet host star radiation and plasma environments, exoplanet upper atmosphere and environment observations, exoplanet and stellar magnetospheres, and exoplanet observation and characterization. The book closes with an outlook on the future of this research field.