From The Outer Heliosphere To The Local Bubble

Knowledge about the outer heliosphere and the interstellar medium, which were long treated as two separate fields, has improved dramatically over the past 25 years as a consequence of recent developments: The discovery of interstellar pickup ions and neutral helium inside the heliosphere, the determination of the interstellar hydrogen distribution in the heliosphere obtained using backscattered solar Lyman-alpha radiation, the prediction and subsequent detection of the hydrogen wall just outside of the heliopause, the development of detailed global models for the interaction of solar wind plasma with the interstellar medium, and most recently, direct in-situ plasma and field measurements inside of the heliosheath. At the same time, our understanding of the nearby galactic environment, including the composition and dynamics of the warm gas clouds and hot gas in the local bubble, has benefited greatly from absorption-line spectroscopy using nearby stars as background sources and dynamic modeling. The present volume provides a synopsis of these developments organised into seven sections: Dominant physical processes in the termination shock and heliosheath, three-dimensional shape and structure of the dynamic heliosphere, relation of the plasmas and dust inside and outside of the heliosphere, origin and properties of the very local interstellar medium, energy and pressure equilibria in the local bubble, physical processes in the multiphase interstellar medium inside of the local bubble, and the roles that magnetic fields play in the outer heliosphere and the local bubble. The last theme is probably the most basic of all as magnetic fields play important roles in most of the phenomena discussed here. The volume concludes with four papers providing the "big picture" by looking at the time evolution of both the heliosphere and the local bubble, looking beyond the local bubble, and finally addressing the challenges in modeling the interface between the two media.

In summary, we can conclude that the contributions of the different ionization processes to the total ionization rate for the most abundant interstellar species are basically known. The ionization of the noble gases He and Ne is almost completely dominated by photoionization, whereas for H charge-exchange with the solar wind is most important. For other species, such as 0 and Ar, both processes contribute significantly. Electron impact ionization can typically contribute by '" 10% to the total rate in the inner Solar System. Because direct measurements of the solar EUV flux are not yet continuously available, the variation of the ionization rate over the solar cycle still contains a relatively large uncertainty. The recent measurements of pickup ion distributions and of the neutral helium gas provide an independent tool to determine the total ionization rate that can be used to cross calibrate with the results obtained for the individual ionization processes. Acknowledgements The authors are grateful to M. Allen for supplying us with new data on photoioniza tion cross-sections compiled by him. We thank also M. Gruntman for drawing our attention to and support in collecting the most recent data on charge-exchange cross-sections. D. R. was supported by grant No. 2 P03C. 004. 09 from the Com mittee for Scientific Research (Poland). This work was also supported in part through NASA contract NAS7-918, NSF Grant INT-911637, NASA Grant NAGW- 2579.

This report is the summary of a workshop held in May 2003 by the Space Studies Board's Committee on Solar and Space Physics to synthesize understanding of the physics of the outer heliosphere and the critical role played by the local interstellar medium (LISM) and to identify directions for the further exploration of this challenging environment.

Written by experts who created the field, this volume explores uncharted scientific territory, with articles discussing the effect of our galactic environment on the heliosphere, planetary system and Earth. Leading experts in diverse fields discuss the physical changes expected as the heliosphere adjusts to its galactic environment. Topics include the interaction between solar wind and interstellar dust and gas, cosmic ray modulation, magnetospheres, variations in the solar environment, and the cosmic ray isotope record preserved in paleoclimate data.

The eleventh COSPAR colloquium The Outer Heliosphere: The Next Frontiers was held in Potsdam, Germany, from 24-28 July, 2000, and is the second dedicated to this subject after the first one held in Warsaw, Poland in 1989. Roughly a century has passed after the first ideas by Oliver Lodge, George Francis Fitzgerald and Kristan Birkeland about particle clouds emanating from the Sun and interacting with the Earth environment. Only a few decades after the formulation of the concepts of a continuous solar corpuscular radiation by Ludwig Bierman and a solar wind by Eugene Parker, heliospheric physics has evolved into an important branch of astrophysical research. Numerous spacecraft missions have increased the knowledge about the heliosphere tremendously. Now, at the beginning of a new millenium it seems possible, by newly developed propulasion technologies to send a spacecraft beyond the boundaries of the heliosphere. Such an Interstellar Proce will start the in-situ exploration of interstellar space and, thus, can be considered as the first true astrophysical spacecraft. The year 2000 appeared to be a highly welcome occassion to review the achievements since the last COSPAR Colloquia 11 years ago, to summarize the present developments and to give new impulse for future activities in heliospheric research.

Proceedings of the Second "Rencontres de l'observatoire", Observatoire de Paris, Meudon, France

Putting the “I” in IHY This book is about international cooperation. It demonstrates how the power of scienti?c imagination and investigation can bring together people form all continents in almost all countries around the globe. In presenting this impressive result, we can understand, how much unifying force the quest for understanding our universe and using outer space for that purpose have. Astronomy is far away from being a “political” area of science. But is has enormous political effects – and all of these effects are positive. This book about the international aspects and achievements of the “International Heliophysical Year (IHY) 2007” can be regarded as a compendium of the fertile impacts of conducting research in this ?eld. The main focus, as the title implicates, is the international cooperation, which has emerged from this grassroots initiative. North and South, industrialized and developing countries have been coordinating their efforts and have been learning from each other in a mutual partnership under a joint understanding of sharing the scienti?c bene?ts. Through this, trans-border networks have been created and scienti?c as well as cultural exchange took place.