New Windows on Massive Stars (IAU S307)


Book Description

Massive stars play a crucial role in the Universe: they are important drivers for the photometric and chemical evolution of galaxies; they are sources of important elements, including those necessary for life; and, with their strong winds and supernova explosions, they feed the interstellar medium with momentum and kinetic energy, impacting on the star formation rate. Knowledge of the evolution of massive stars is important not only for stellar physics, but also for probing the evolution of galaxies and their star formation histories throughout cosmic time. This volume provides an introduction to these topics and to the techniques used to investigate the properties of massive stars, including asteroseismology, spectropolarimetry, and interferometry. It highlights synergies between these new techniques and more classical methods, to create a synthetic view of massive stars, leading researchers towards new and innovative solutions to the most topical questions regarding the evolution of massive stars.




Interior Modelling of Massive Stars in Multiple Systems


Book Description

This thesis by Cole Johnston brings novel insights into the inner workings of young massive stars. By bridging the observational fields of binary stars and asteroseismology this thesis uses state of the art statistical techniques to scrutinise theories of modern stellar astrophysics. Developing upon the commonly used isochrone fitting methodology, the author introduces the idea of isochrone cloud fitting in order to account for the full breadth of physics observed in stars. The author combines this methodology with gravity mode asteroseismic analysis to asses the level of chemical mixing deep within the stellar core in order to determine the star‘s age and core mass. Wrapped into a robust statistical framework to account for correlations, this methodology is employed to analyse individual stars, multiple systems, and clusters alike to demonstrate that chemical mixing has dramatic impact on stellar structure and evolution.




Luminous Stars in Nearby Galaxies


Book Description

Studies on the populations of luminous stars in nearby resolved galaxies have revealed a complex distribution in the luminosity–temperature plane (the HR diagram). The fundamentals of massive star evolution are mostly understood, but the roles of mass loss, episodic mass loss, rotation, and binarity are still in question. Moreover, the final stages of these stars of different masses and their possible relation to each other are not understood. The purpose of this volume is to provide a current review of the different populations of evolved massive stars. The emphasis is on massive stars in the Local Group, the Magellanic Clouds, and the nearby spirals M31 and M33.




Observational Imprints of Binary Evolution on B- and Be-star Populations


Book Description

This book presents novel observational evidence toward detecting and characterizing the products of massive, interacting binary stars. As a majority of massive stars are born in close binary systems, a large number of so-called massive binary interaction products are predicted to exist; however, few have been identified so far. Based on observations with the largest telescopes around the world, equipped with state-of-the-art instrumentation, this book helps to remedy this situation. In her outstanding PhD-thesis Julia Bodensteiner identifies a new class of post-interaction binaries in a short-lived phase just briefly after the initially more massive star has been stripped of part of its envelope. She further provides new evidence for the Be phenomenon to largely result from binary interactions. These results represented a new and testable prediction for the evolution of these stars and opened up a new way forward for identifying hundreds of post-interaction products. Finally, using the MUSE integral field spectrograph at the Very Large Telescope in Chile, the author presents a novel spectroscopic campaign focusing on the 40 Myr-old star cluster NGC 330 in the Small Magellanic Clouds. Combined with photometric observations from the Hubble Space Telescope, the MUSE data allow to characterize the entire massive star population of NGC 330, revealing their multiplicity properties and rotational velocities and providing unique observational constraints on their (binary) evolution history. This is made possible by the developments of novel numerical methods allowing to extract star spectra from the MUSE integral field spectroscopic data and to characterize their properties by the simultaneous comparison of MUSE spectroscopy and Hubble photometry with atmospheric models. This book is a partly re-written version of the author's thesis offering a highly readable coherent text presenting not only new insights into the properties of binary interaction products but also giving students an excellent introduction into the field.




Astrophysics with Radioactive Isotopes


Book Description

Dealing with astrophysics derived from the radiation emitted by radioactive atomic nuclei, this book describes the different methods used to measure cosmic radio-isotopes. It demonstrates how this astronomical window has contributed to the understanding of the sources and the chemical evolution of cosmic gas. Reference materials and explanations are included for students in advanced stages of their education. Nuclear reactions in different sites across the universe lead to the production of stable and unstable nuclei. Their abundances can be measured through different methods, allowing to study the various nuclear processes taking place in cosmic environments. Nucleosynthesis is the cosmic formation of new nuclear species, starting from hydrogen and helium resulting from the big bang origins. Stars create and eject synthesized nuclei during their evolution and explosions. Incorporation of the new interstellar composition into next-generation stars characterises the compositional (chemical) evolution of cosmic gas in and between galaxies. Radioactive species have unique messages about how this occurs. Since the first Edition of this book published in 2011 with the title Astronomy with Radioactivities, long-awaited new direct observations of supernova radioactivity have been made and are now addressed in two updated chapters dealing with supernovae. In this second Edition, the advances of recent years beyond one-dimensional treatments of stellar structure and stellar explosions towards 3-dimensional models have been included, and led to significant re-writings in Chapters 3-5. The sections on the Solar System origins have been re-written to account for new insights into the evolution of giant molecular clouds. The chapter on diffuse radioactivities now also includes material measurements of radioactivities in the current solar system, and their interpretations for recent nucleosynthesis activity in our Galaxy. Significant new results on gamma-rays from positron annihilations have been accounted for in that chapter, and led to new links with nucleosynthesis sources as well as interstellar transport processes. A new chapter now provides a description of interstellar processes often called 'chemical evolution', thus linking the creation of new nuclei to their abundance observations in gas and stars. The experimental / instrumental chapters on nuclear reaction measurements, on gamma-ray telescopes, and pre-solar grain laboratories have been updated. Moreover, new windows of astronomy that have been opened up in recent years have been included in the discussions of the multi-messenger approach that broadens the basis for astrophysical insights.




Asteroseismology in the Kepler Era


Book Description




Evolution of Peculiar Red Giant Stars


Book Description

Red giant stars are evolutionarily advanced objects in the closing stages of their nuclear burning lifetime. Observed with increasing spectral coverage they display a variety of unusual phenomena. Many are characterized by peculiar (non-solar) surface chemical compositions which provide otherwise unobtainable clues to interior nucleosynthesis, mixing and evolution. Others may have received their chemical peculiarities by mass transfer from a companion. This book reports on the proceedings of the International Astronomical Union Colloquium 106. It contains discussions on many aspects of these stars, combining theory and observation to interpret these objects in terms of their evolutionary history. There are 20 review papers, 69 abstracts and short contributed papers and a complete transcript of the valuable summary panel discussion. Professional astronomers will find this book useful as a reference work which incorporates current research on the modelling and evolution of these unstable stars.




New Perspectives on Stellar Pulsation and Pulsating Variable Stars


Book Description

How can the interior of the Sun, white dwarfs and other stars be studied by stellar seismology? What can Doppler imaging tell us about high-degree pulsations? What impact are CCD and infrared observations having on extending the Cepheid and RR Lyrae distance scale? And how are other classes of pulsators providing independent checks of the distance scale? These and many other critical questions are answered in this timely review of the dramatic advances made in pulsating star research in the last decade. This survey collects together more than thirty comprehensive reviews and over one hundred summaries of research papers from the 139th IAU Colloquium, held in Victoria, British Columbia. Together these cover all aspects of recent developments in the field of variable star research and preview some of the exciting advances anticipated for the next decade. This volume provides an essential review for graduate students and researchers.




Populations of High-Energy Sources in Galaxies (IAU S230)


Book Description

For the last 40 years astronomers have observed sources of intense X-ray radiation from beyond our Solar System. These have been associated with remarkable objects, such as neutron stars and black holes. Current satellite observatories have enabled us to extend the studies of these objects from the Milky Way and Magellanic Clouds to individual X-ray sources in other galaxies. At the same time, imaging facilities at gamma-rays and TeV energies have improved enormously, leading to many further discoveries within our own galaxy. This Symposium presents an overview of these new developments, covering detailed studies of individual sources within the Milky Way, global descriptions of X-ray source populations in other galaxies, and less resolved relatives at high redshift. Galaxy nuclei and diffuse emission components are included, as are new discoveries at gamma-rays and TeV energies. IAU S230 is a valuable resource for astronomers and graduates working in high-energy astrophysics.