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Title: Unsteady processes in the vicinity of the heliopause: Are we in the LISM yet?

As the twin Voyager spacecraft approach the boundary of the heliosphere, they continue returning new and unexplained measurements of the solar wind (SW) protons, energetic particles, and magnetic field that often differ markedly between the two spacecraft. Our recent studies show that time-dependent effects play a crucial role in understanding and interpreting the observational data. Since the SW is unsteady on many different time scales, its interaction with the local interstellar medium (LISM) should reflect the solar rotation and cycle, as well as merged interplanetary disturbances. Even a simplified solar cycle model allowed us to predict in 2009 the possibility of a negative radial velocity component in the SWas the heliopause is approached. Further analysis shows a nearly vanishing latitudinal velocity component, while the longitudinal component becomes comparable substantial. Here we discuss the change of the magnetic field and plasma properties across the heliopause, which is important for the identification of its spacecraft crossing. In conclusion, we discuss the effects of heliopause instabilities and corotating interaction regions, and demonstrate that Voyagers are unlikely to see a sharp boundary between the SW and the LISM, but rather a mixing layer of varying width.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [5] ;  [1] ;  [1]
  1. Univ. of Alabama, Huntsville, AL (United States). Dept. of Physics and Center for Space Plasma and Aeronomic Research (CSPAR)
  2. Univ. of Alabama, Huntsville, AL (United States). Center for Space Plasma and Aeronomic Research (CSPAR)
  3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States). Heliospheric Science Division
  4. Southwest Research Inst. (SwRI), San Antonio, TX (United States)
  5. National Space Science and Technology Center (NSSTC), Huntsville, AL (United States)
Publication Date:
Grant/Contract Number:
SC0008334; NNX08AE41G; NNX08AG62G; NNX08AJ21G; NNX09AB24G, NNX09AG29G, NNX09AP74A; NNX09AW44G; NNX09AG63G; NNX10AE46G; NNX12AB30G
Type:
Accepted Manuscript
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1539; Conference: SOLAR WIND 13: Proceedings of the Thirteenth International Solar Wind Conference, Big Island, Hawaii (United States), 17-22 Jun 2012; Journal ID: ISSN 0094-243X
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Alabama, Huntsville, AL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; interplanetary and interstellar magnetic fields; heliopause, solar wind termination, solar cycle variations; multi-fluid plasma; magnetohydrodynamics
OSTI Identifier:
1326064

Pogorelov, N. V., Borovikov, S. N., Burlaga, L. F., Ebert, R. W., Kryukov, I. A., Suess, S. T., Zank, G. P., and Bedford, M. C.. Unsteady processes in the vicinity of the heliopause: Are we in the LISM yet?. United States: N. p., Web. doi:10.1063/1.4811059.
Pogorelov, N. V., Borovikov, S. N., Burlaga, L. F., Ebert, R. W., Kryukov, I. A., Suess, S. T., Zank, G. P., & Bedford, M. C.. Unsteady processes in the vicinity of the heliopause: Are we in the LISM yet?. United States. doi:10.1063/1.4811059.
Pogorelov, N. V., Borovikov, S. N., Burlaga, L. F., Ebert, R. W., Kryukov, I. A., Suess, S. T., Zank, G. P., and Bedford, M. C.. 2013. "Unsteady processes in the vicinity of the heliopause: Are we in the LISM yet?". United States. doi:10.1063/1.4811059. https://www.osti.gov/servlets/purl/1326064.
@article{osti_1326064,
title = {Unsteady processes in the vicinity of the heliopause: Are we in the LISM yet?},
author = {Pogorelov, N. V. and Borovikov, S. N. and Burlaga, L. F. and Ebert, R. W. and Kryukov, I. A. and Suess, S. T. and Zank, G. P. and Bedford, M. C.},
abstractNote = {As the twin Voyager spacecraft approach the boundary of the heliosphere, they continue returning new and unexplained measurements of the solar wind (SW) protons, energetic particles, and magnetic field that often differ markedly between the two spacecraft. Our recent studies show that time-dependent effects play a crucial role in understanding and interpreting the observational data. Since the SW is unsteady on many different time scales, its interaction with the local interstellar medium (LISM) should reflect the solar rotation and cycle, as well as merged interplanetary disturbances. Even a simplified solar cycle model allowed us to predict in 2009 the possibility of a negative radial velocity component in the SWas the heliopause is approached. Further analysis shows a nearly vanishing latitudinal velocity component, while the longitudinal component becomes comparable substantial. Here we discuss the change of the magnetic field and plasma properties across the heliopause, which is important for the identification of its spacecraft crossing. In conclusion, we discuss the effects of heliopause instabilities and corotating interaction regions, and demonstrate that Voyagers are unlikely to see a sharp boundary between the SW and the LISM, but rather a mixing layer of varying width.},
doi = {10.1063/1.4811059},
journal = {AIP Conference Proceedings},
number = ,
volume = 1539,
place = {United States},
year = {2013},
month = {6}
}