It is now clear that a binary evolutionary pathway is responsible for a significant fraction of all planetary nebulae, with some authors even going so far as to claim that binarity may be a near requirement for the formation of an observable nebula. This has led to the requirement that textbooks most likely need to be rewritten. Building upon the review of Jones and Boffin in Nature Astronomy (2017), this Springer Brief takes a first step in this direction. It offers the first expanded presentation of all the theoretical and observational support for the importance of binarity in the formation of planetary nebulae, initially focusing on common envelope evolution but also covering wider binaries. This book emphasises the wider impact of the field, highlighting the critical role binary central stars of planetary nebulae have in understanding a plethora of astrophysical phenomena, including type Ia supernovae, chemically peculiar stars and circumbinary exoplanets.

Stars are mostly found in binary and multiple systems, with at least 50% of all solar-like stars having companions; this fraction approaches 100% for the most massive stars. A large proportion of these systems interact and alter the structure and evolution of their components, leading to exotic objects such as Algol variables, blue stragglers and other chemically peculiar stars, but also to phenomena such as non-spherical planetary nebulae, supernovae and gamma-ray bursts. While it is understood that binaries play a critical role in the Initial Mass Function, the interactions among binary systems significantly affect the dynamical evolution of stellar clusters and galaxies. This interdisciplinary volume presents results from state-of-the-art models and observations aimed at studying the impact of binaries on stellar evolution in resolved and unresolved populations. Serving as a bridge between observational and theoretical astronomy, it is a comprehensive review for researchers and advanced students of astrophysics.

This book contains the best and most up-to-date contributions in the field of late stage stellar evolution, as presented at the APNVII conference in Hong Kong in December 2017. A total of 60 scientists from 20 countries gathered to present, listen, interact and discuss the most current issues and problems in planetary nebulae and related objects research. The emphasis of this influential series of meetings, which was the seventh occasion over the last 20 years, has always been on the hypothesized and observed physical shaping mechanisms of the ejected nebulae that have such wonderful and intriguing forms. This special Galaxies conference issue of fully refereed contributions brings together a representative compilation of the meeting presentations in paper form. It captures the current “snap shot” status of this research field in some real sense. Such proceedings are well received and can be used as a reference material by both participants and all others working in the field for years to come.

A large majority of planetary nebulae (PNe) are non-spherical, and many have complex structures; these are unlikely to be created trivially by a single central star. The Binary Hypothesis proposes that the complex morphologies of most non-spherical PNe are caused by interactions between their central stars and companions, with some unknown percentage in close binary systems. In this study, a software pipeline was developed to generate light curves for 140 PNe targets from the Kepler K2 campaign 11 field. Of these 140 targets, 29 appeared to show periodicity in their light curves, all of which had period under two weeks, for a close binary fraction of 21%; furthermore, 25 out of 29 (86%) detected periods were between two hours and five days. The size of this data set (140 PNe) is larger than any previous photometric search for close binary companions of PNe central stars, and the calculated short-period binary fraction is consistent with past photometric searches. These results support the Binary Hypothesis, which in turn helps explain the development of the varied and complex morphologies of PNe.

In this book we will look at what planetary nebulae are, where they come from and where they go. We will discuss what mechanisms cause these beautiful markers of stellar demise as well as what causes them to form their variety of shapes. How we measure various aspects of planetary nebulae such as what they are made of will also be explored. Though we will give some aspects of planetary nebulae mathematical treatment, the main points should be accessible to people with only a limited background in mathematics. A short glossary of some of the more arcane astronomical terms is at the end of the book to help in understanding. Included at the end of each chapter is an extensive bibliography to the peer reviewed research on these objects and I would encourage the reader interested in an even deeper understanding to read these articles.