**Author details**

*Solar System Planets and Exoplanets*

field as it is the case along the earth's wake.

justifies the importance of the fluid dynamic approach.

Ann Pérez-de-Tejada for comments received.

**5. Conclusions**

**Acknowledgements**

should produce vortex structures that are situated at different locations along its plasma wake. External to the solar system it is also possible that exo-planets moving within stellar systems will be subject to stellar winds that do not have the same intensity and thus arrive from different directions. In such cases vortex structures may be present at varying distances along their wake and be located at varying distances downstream from exo-planets. Stellar winds with different flow intensity, plasma temperature, and stellar irradiance will in addition influence the position and configuration of vortex structures in an exo-planet wake. A notable effect is the subsonic to supersonic speed change that depends on the coronal temperature of a star as implied from the solution of the fluid dynamic Parker equations of solar wind acceleration [15]. Equally important is the requirement that fluid dynamic vortex structures will be influenced by a planetary magnetic

The fluid dynamic response of the solar wind that interacts with planetary ionospheres is ultimately produced by wave-particle interactions inferred from the observation of frequent oscillations in magnetic field profiles measured in the Venus wake [16–18]. As a whole such interactions provide a mechanism to transfer momentum between both ion populations and thus erode the upper layers of the Venus ionosphere [2]. That process implies in turn local plasma heating [19, see Fig. 35; 20, 21] and the removal of ionospheric plasma in the form of channels or ducts that extend downstream along the Venus wake [22, 23]. These various features are in agreement with phenomena observed in fluid dynamic problems and provide an account of measurements conducted in the Venus wake with various spacecraft. The identification of vortex structures in the Venus wake whose position and width varies during the solar cycle provides a remarkable result that

We wish to thank Gilberto A. Casillas for technical work provided. Financial support was available from the INAM-IN108814-3 Project. Appreciation is given to

**70**

H. Pérez-de-Tejada1 \* and R. Lundin2

1 Institute of Geophysics, UNAM, Mexico

2 Swedish Space Research Institute, Kiruna, Sweden

\*Address all correspondence to: hectorperezdetejada@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
