Non-equilibrium stationary states in the heliosphere and the influence of pick-up ions

G. Livadiotis, D. J. McComas

Research output: Chapter in Book/Report/Conference proceedingConference contribution

13 Scopus citations

Abstract

Space plasmas from the solar wind to planetary magnetospheres and the outer heliosphere are systems in stationary states out of equilibrium. Empirical kappa distributions successfully describe these space plasmas. Non-extensive Statistical Mechanics offers a solid statistical foundation and provides a set of proven tools for understanding these distributions. Here, by expressing the entropy in terms of the κ-index, we show the detailed paths by which the transition of stationary states evolves toward equilibrium. This procedure naturally provides four indices that are frequently observed in space plasmas: The extreme kappa values of infinity and ∼1.5 correspond to the stationary states at equilibrium and the furthest state from equilibrium, respectively; the value of κ∼1.63 is the fundamental state exhibiting the minimum entropy; and the value of κ∼2.45 is the escape state which separates the near-equilibrium states included in the monotonic region κ>2.45, from the far-equilibrium states included in the non-monotonic cavity of 2.45>κ>1.5. The fundamental state separates the entropy in two monotonic branches, κ>1.63 (A) and 1.63>κ (D). As the entropy increases, the value of κ-index increases along the A-branch, while it decreases along the D-branch, exhibiting a phenomenological Acceleration or Deceleration of particles, respectively. Starting from stationary states near the fundamental state, spontaneous procedures that increase entropy, move the system toward equilibrium either directly, along the A-branch, or indirectly, along the D-branch first, and then, along the A-branch, after isentropic switching between the branches. Finally, external factors that can decrease the entropy of the system, move it back into stationary states closer to the fundamental state. In the case of solar wind, newly formed pick-up ions play just such a role because their motion is highly ordered.

Original languageEnglish (US)
Title of host publicationPickup Ions Throughout the Heliosphere and Beyond - Proceedings of the 9th Annual International Astrophysics Conference
Subtitle of host publicationDedicated to the Memory of Sir W. Ian Axford January 2, 1933 - March 13, 2010
Pages70-76
Number of pages7
DOIs
StatePublished - Dec 1 2010
Externally publishedYes
Event9th Annual International Astrophysics Conference on Pickup Ions Throughout the Heliosphere and Beyond: Dedicated to the Memory of Sir W. Ian Axford January 2, 1933 - March 13, 2010 - Maui, HI, United States
Duration: Mar 14 2010Mar 19 2010

Publication series

NameAIP Conference Proceedings
Volume1302
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other9th Annual International Astrophysics Conference on Pickup Ions Throughout the Heliosphere and Beyond: Dedicated to the Memory of Sir W. Ian Axford January 2, 1933 - March 13, 2010
CountryUnited States
CityMaui, HI
Period3/14/103/19/10

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Plant Science
  • Physics and Astronomy(all)
  • Nature and Landscape Conservation

Keywords

  • entropy
  • Non-equilibrium states
  • solar wind
  • space plasmas

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    Livadiotis, G., & McComas, D. J. (2010). Non-equilibrium stationary states in the heliosphere and the influence of pick-up ions. In Pickup Ions Throughout the Heliosphere and Beyond - Proceedings of the 9th Annual International Astrophysics Conference: Dedicated to the Memory of Sir W. Ian Axford January 2, 1933 - March 13, 2010 (pp. 70-76). (AIP Conference Proceedings; Vol. 1302). https://doi.org/10.1063/1.3529993