National Academies Press: OpenBook

Plasma Physics of the Local Cosmos (2004)

Chapter: 7 Concluding Thoughts

« Previous: 6 Energetic Particle Acceleration
Suggested Citation:"7 Concluding Thoughts." National Research Council. 2004. Plasma Physics of the Local Cosmos. Washington, DC: The National Academies Press. doi: 10.17226/10993.
×

7
Concluding Thoughts

Our solar system, and stellar systems in general, are rich in the dynamical behaviors of plasma, gas, and dust organized and affected by magnetic fields. These dynamical processes are ubiquitous to highly evolved stellar systems, such as our own, but also play important roles in their formation and evolution. Stellar systems are born out of clumpy, rotating, primordial nebulas of gas and dust. Gravitational contraction, sometimes aided by shock waves (possibly from supernovas), passage through dense material, and other disruptions, forms condensation centers that eventually become stars, planets, and small bodies. Magnetic fields moderate early-phase contractions and may also play vital roles in generating jets and shedding angular momentum, allowing further contraction. The densest of the condensation centers become protostars surrounded by accretion disks. Dynamo action occurs within the protostars as the heat of contraction ionizes their outer gaseous layers, resulting in stellar winds. In similar fashion, rotating solid and gaseous planets form, and many of these also support dynamo action, producing magnetic fields. Ultraviolet and x-ray photons from the central stars partially ionize the upper atmospheres of the planets as well as any interstellar neutral atoms that traverse the systems. Viewed as a whole, the resulting plasma environments are called asterospheres, or in the Sun’s case, the heliosphere. In its present manifestation, the heliosphere—the local cosmos—is a fascinating corner of the universe, challenging our best scientific efforts to understand its diverse machinations. It must be appreciated at the same time that our local cosmos is a laboratory for investigating the complex dynamics of active plasmas and fields that occur throughout the universe from the smallest ionospheric scales to galactic scales. Close inspection and direct samplings within the heliosphere are essential parts of the investigations that cannot be carried out by a priori theoretical efforts alone.

This report summarizes much of what is known about the plasma physics of the local cosmos and lists many of the outstanding questions that will be driving the field for the near future. The discussions are organized around five broad themes, specifically (1) the creation and annihilation of magnetic fields, (2) the formation of structures and transients, (3) plasma interactions, (4) explosive energy conversion, and (5) energetic particle acceleration. These phenomena have been identified, and questions posed, in terms of specific observables either on the Sun or in various parts of the heliosphere and planetary systems. The

Suggested Citation:"7 Concluding Thoughts." National Research Council. 2004. Plasma Physics of the Local Cosmos. Washington, DC: The National Academies Press. doi: 10.17226/10993.
×

proposed solutions and experiments are also designed for the parameter ranges found in the local cosmos. Nonetheless, in every case the solutions are of universal applicability, and a challenge for solar and space physics in the future is to extend the models and theories that have been validated in the local cosmos to nonlocal astrophysical plasmas. It is obvious, for example, that the theories of magnetic dynamos and magnetic reconnection must be applicable to the generation of magnetic fields and to the explosive conversion of magnetic energy to heat and particle kinetic energy in every corner of the universe. Likewise, the acceleration of charged particles to high energies by shock waves and by both parallel and perpendicular electric fields is certainly of universal importance. Obstacles to plasma flows exist everywhere, and the interaction between two magnetized plasma populations can produce magnetic stresses that are relieved with cross-scale coupling processes that occur either gradually or explosively depending upon the capabilities of each plasma region.

As the discipline of solar and space physics has matured, the focus has become less on places to explore than on fundamental processes to investigate and understand. Understanding requires that the processes be investigated in diverse plasma environments. Important to this investigation are space missions to the magnetospheres of other planets as well as that of Earth, missions to sample the properties of the heliosphere, missions to observe the astonishing fine structure of the active Sun, and multispacecraft missions to sample the structure of magnetopauses, shock transitions, and the magnetic reconnection processes. The results must be fed into the latest theoretical models, and it is these models that provide the links to other parts of the cosmos. Thus, a plasma theory and modeling program that cuts across the disciplines of solar physics, space physics, and astrophysics is an important part of any efforts to understand the plasma physics of the cosmos.

Suggested Citation:"7 Concluding Thoughts." National Research Council. 2004. Plasma Physics of the Local Cosmos. Washington, DC: The National Academies Press. doi: 10.17226/10993.
×
Page 77
Suggested Citation:"7 Concluding Thoughts." National Research Council. 2004. Plasma Physics of the Local Cosmos. Washington, DC: The National Academies Press. doi: 10.17226/10993.
×
Page 78
Next: Appendix A: Statement of Task »
Plasma Physics of the Local Cosmos Get This Book
×
Buy Paperback | $29.00 Buy Ebook | $23.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Solar and space physics is the study of solar system phenomena that occur in the plasma state. Examples include sunspots, the solar wind, planetary magnetospheres, radiation belts, and the aurora. While each is a distinct phenomenon, there are commonalities among them. To help define and systematize these universal aspects of the field of space physics, the National Research Council was asked by NASA’s Office of Space Science to provide a scientific assessment and strategy for the study of magnetized plasmas in the solar system. This report presents that assessment. It covers a number of important research goals for solar and space physics. The report is complementary to the NRC report, The Sun to the Earth—and Beyond: A Decadal Research Strategy for Solar and Space Physics, which presents priorities and strategies for future program activities.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!