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Title: The solar cycle dependence of the location and shape of the Venus bow shock

Abstract

From initial Pioneer Venus observations during the maximum of solar cycle 21 it was evident that the position of the Venus bow shock varies with solar activity. The bow shock radius in the terminator plane changed from 2.4 R{sub v} to 2.1 R{sub v} as solar activity went from maximum to minimum and, as activity has increased in cycle 22, it has increased again. The recent studies of the subsolar region show that the altitude of the nose of the bow shock varies from 1,600 km at solar minimum to 2,200 km at intermediate solar activity in concert with the terminator altitude so that the shape remains constant and only the size varies during the solar cycle. Using a gas dynamic model and the observed bow shock location, the authors infer the variation in the size of the effective obstacle during the solar cycle. At solar maximum, the effective obstacle is larger than the ionopause as if a magnetic barrier exists in the inner magnetosheath. This magnetic barrier acts as the effective obstacle deflecting the magnetosheath plasma about 500 km above the surface of Venus. However, at solar minimum the effective obstacle is well below the subsolar ionopause, and somemore » absorption of the solar wind plasma by the Venus neutral atmosphere is suggested by these observations. The dependence of the solar cycle variation of the shock position on the orientation of the interplanetary magnetic field reinforces the idea that planetary ion pickup is important in the interaction of the solar wind with Venus.« less

Authors:
; ;  [1]
  1. Univ. of California, Los Angeles (USA)
Publication Date:
OSTI Identifier:
5445024
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research; (United States)
Additional Journal Information:
Journal Volume: 95:A9; Journal ID: ISSN 0148-0227
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; SOLAR WIND; INTERACTIONS; VENUS PLANET; COORDINATES; MASS TRANSFER; MATHEMATICAL MODELS; PIONEER SPACE PROBES; PLANETARY IONOSPHERES; SHOCK WAVES; SOLAR ACTIVITY; SOLAR CYCLE; VARIATIONS; PLANETS; SPACE VEHICLES; VEHICLES; 640107* - Astrophysics & Cosmology- Planetary Phenomena

Citation Formats

Zhang, T L, Luhmann, J G, and Russell, C T. The solar cycle dependence of the location and shape of the Venus bow shock. United States: N. p., 1990. Web. doi:10.1029/JA095iA09p14961.
Zhang, T L, Luhmann, J G, & Russell, C T. The solar cycle dependence of the location and shape of the Venus bow shock. United States. https://doi.org/10.1029/JA095iA09p14961
Zhang, T L, Luhmann, J G, and Russell, C T. 1990. "The solar cycle dependence of the location and shape of the Venus bow shock". United States. https://doi.org/10.1029/JA095iA09p14961.
@article{osti_5445024,
title = {The solar cycle dependence of the location and shape of the Venus bow shock},
author = {Zhang, T L and Luhmann, J G and Russell, C T},
abstractNote = {From initial Pioneer Venus observations during the maximum of solar cycle 21 it was evident that the position of the Venus bow shock varies with solar activity. The bow shock radius in the terminator plane changed from 2.4 R{sub v} to 2.1 R{sub v} as solar activity went from maximum to minimum and, as activity has increased in cycle 22, it has increased again. The recent studies of the subsolar region show that the altitude of the nose of the bow shock varies from 1,600 km at solar minimum to 2,200 km at intermediate solar activity in concert with the terminator altitude so that the shape remains constant and only the size varies during the solar cycle. Using a gas dynamic model and the observed bow shock location, the authors infer the variation in the size of the effective obstacle during the solar cycle. At solar maximum, the effective obstacle is larger than the ionopause as if a magnetic barrier exists in the inner magnetosheath. This magnetic barrier acts as the effective obstacle deflecting the magnetosheath plasma about 500 km above the surface of Venus. However, at solar minimum the effective obstacle is well below the subsolar ionopause, and some absorption of the solar wind plasma by the Venus neutral atmosphere is suggested by these observations. The dependence of the solar cycle variation of the shock position on the orientation of the interplanetary magnetic field reinforces the idea that planetary ion pickup is important in the interaction of the solar wind with Venus.},
doi = {10.1029/JA095iA09p14961},
url = {https://www.osti.gov/biblio/5445024}, journal = {Journal of Geophysical Research; (United States)},
issn = {0148-0227},
number = ,
volume = 95:A9,
place = {United States},
year = {Sat Sep 01 00:00:00 EDT 1990},
month = {Sat Sep 01 00:00:00 EDT 1990}
}