Systems of two or more stars are called multiple star systems. These systems, especially when more distant, often appear to the unaided eye as a single point of light, and are then revealed as multiple by other means. Research over the last two centuries suggests that half or more of visible stars are part of multiple star systems.
The term double star is often used synonymously with binary star; however, double star can also mean optical double star. Optical doubles are so called because the two stars appear close together in the sky as seen from the Earth. They are almost on the same line of sight.
Nevertheless, their doubleness depends only on this optical effect. The stars themselves are distant from one another and share no physical connection. A double star can be revealed as optical by means of differences in their parallax measurements, proper motions, or radial velocities.
Most known double stars haven’t been studied adequately to determine if they are optical doubles or doubles physically bound through gravitation into a multiple star system.
Binary star systems are very important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined, which in turn allows other stellar parameters, such as radius and density, to be indirectly estimated. This also determines an empirical mass-luminosity relationship (MLR) from which the masses of single stars can be estimated.
Forty specialists in astronomy, physics and astrophysics all over Europe and elsewhere in the world in 14 countries – Austria, Belgium, Czech Republic, Chile, Germany, Israel, Italy, the Netherlands, New Zealand, Poland, Spain, Switzerland, the United Kingdom, and the United states – authored the 21 chapters of this book named below to provide you an overview:
- The Zoo of Binary Stars
- Statistics of Binary and Multiple Stars
- Gaia and LSST: Their Importance in Binary Star Research
- Population Synthesis of Binary Stars
- Low- and Intermediate-Mass Star Evolution: Open Problems
- The Symbolic Stars
- Binary Post-AGB Stars as Tracers of Stellar Evolution
- The Importance of Binarity in the Formation and Evolution of Planetary Nebulae
- Massive Star Evolution: Binaries as Two Single Stars
- Binary at High Masses
- Luminous Blue Variables: Formation, Instability in the Context of Binary Intersections
- Type Ia Supernovae: Where Are They Coming From and Where Will They Lead Us?
- Binary Interactions and Gamma-Ray Bursts
- Binaries As Sources of Gravitational Waves
- The Impact of Binaries on the Stellar Initial Mass Function
- The Formation of Binary Stars: Insights From Theory and Observation
- The Maxwell’s Demon of Star Clusters
- Alternative Stellar Evolution Pathways
- Clocks and Scales: Playing with the Physics of Blue Stragglers
- Binaries at Very Low Metallicity
- Population and Spectral Synthesis
In this book, the editors basically point out that in the last few decades, there has been a paradigm shift with the realization that stars are mostly found in binary or multiple systems. At least 50 percent of all solar-like stars have companions, and the percentage goes as high as 100 percent for most of the massive stars that have been observed.
Also, a large number of them will interact in some way or another. Such interactions will often alter the structure and evolution of both components of the system. Most massive stars may in fact be mergers of initially smaller stars. They also point out that one of the most luminous stars in our galaxy – the n Carinae – is a binary.
The contents of this book are a legacy from the July 3-7, 2017 conference of the European Southern Observatory (ESO) held in Garching, a city in Bavaria, Germany. Its theme was “The Impact of Binaries on Stellar Evolution.”
This book is unique in the sense that it sheds light on binary stars and star systems, about which not much was known in the past. For that reason, it’s an important and pioneering contribution to the field of astronomy by Giacomo Beccari and Henri M.J. Boffin and all those who contributed to this enlightening book.
Giacomo Beccari is a staff astronomer at the European Southern Observatory. His work is focused on the study of Blue Straggler stars in Globular Clusters. He is a former winner of the Levi-Montalcini Prize and coauthor of The Ecology of Blue Straggler Stars.
Henri M.J. Boffin is a staff astronomer at the European Southern Observatory. Recently he has shown the importance of binary stars in explaining planetary nebulae, including discovering the binary star of Fleming I. He pioneered the use of optical interferometry to study mass transfer in symbiotic stars.