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1 - The Zoo of Binary Stars
Edited by Giacomo Beccari, European Southern Observatory, Garching, Henri M. J. Boffin, European Southern Observatory, Garching
Book:

The Impact of Binary Stars on Stellar Evolution

Published online:

05 April 2019

Print publication:

18 April 2019, pp 1-11
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Summary

Stars are mostly found in binary and multiple systems, as at least 50% of all solarlike stars have companions – a fraction that goes up to 100% for the most massive stars. Moreover, a large fraction of them will interact in some way or another: at least half of the binary systems containing solarlike stars, in particular when the primary will evolve on the Asymptotic Giant Branch and at least 70% of all massive stars. Such interactions can, and often will, alter the structure and evolution of both components in the system. This will, in turn, lead to the production of exotic objects whose existence cannot be explained by standard stellar evolution models. Moreover, the chapter explores one of the most luminous stars in our Galaxy, Eta Carinae. The year 2016 saw the first ever announcement of the detection of gravitational waves, coming from the merging of a binary black hole. In this chapter, the author leads the reader through a walk in the zoo of binary stars, highlighting some specific examples.

Edited by Giacomo Beccari, Henri M. J. Boffin
Published online:

05 April 2019

Print publication:

18 April 2019
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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.

Exoplanet Upper Atmosphere Environment Characterization
Helmut Lammer, Kristina G. Kislyakova, Petra Odert, Martin Leitzinger, Maxim L. Khodachenko, Mats Holmström, Arnold Hanslmeier
Journal:

Proceedings of the International Astronomical Union / Volume 7 / Issue S282 / July 2011

Published online by Cambridge University Press:

23 April 2012, pp. 525-532

Print publication:

July 2011
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The intense stellar SXR and EUV radiation exposure at “Hot Jupiters” causes profound responses to their upper atmosphere structures. Thermospheric temperatures can reach several thousands of Kelvins, which result in dissociation of H2 to H and ionization of H to H+. Depending on the density and orbit location of the exoplanet, as a result of these high temperatures the thermosphere expands dynamically up to the Roche lobe, so that geometric blow-off with large mass loss rates and intense interaction with the stellar wind plasma can occur. UV transit observations together with advanced numerical models can be used to gain knowledge on stellar plasma and the planet's magnetic properties, as well as the upper atmosphere.