Living Around Active Stars Proceedings IAU Symposium No. 328, 2016 D. Nandy, A. Valio & P. Petit, eds. c  International Astronomical Union 2017 doi:10.1017/S1743921317003672 A study on Electron Oscillations in the Magnetosheath of Mars with Mars Express observations Adriane M. de Souza 1 , Ezequiel Echer 1 , Mauricio J. A. Bolzam 2 and Markus Fr¨ anz 3 1 National Institute For Space Research Sao Jose dos Campos, Brazil 2 Federal University of Goias, Jatai, Brazil 3 Max Planck Institute for Solar System Research, G¨ ottingen, Germany, email: adriane.souza@inpe.br Abstract. Wavelet analysis was employed to identify the major frequencies of low-frequency waves present in the Martian magnetosheath. The Morlet wavelet transform was selected and applied to the electron density data, obtained from the Analyzer of Space Plasmas and Energetic Atoms experiment (ASPERA-3), onboard the Mars Express (MEX) spacecraft. We have selected magnetosheath crossings and analyzed electron density data. From a preliminary study of 502 magnetosheath crossings (observed during the year of 2005), we have found 1409 periods between 0.005 and 0.06Hz . The major frequencies observed were in the range 0.005-0.02 Hz with 58.5% of the 1409 frequencies identified. Keywords. Mars Magnetosheath, Electron Oscillations, Wavelet Transform 1. Introduction In planets lacking an internal magnetic field, the principal form of interaction between the solar wind and the body is through electro-magnetic induction. This induction can occur in conductive layers inside the planet or in an ionosphere, if the planet has an atmo- sphere. The induced electric currents flow through the planet or through the ionosphere and create forces that causes deceleration and deflection of the incident flow. Thereby, the deflected solar wind stream flows around a region similar to a magnetosphere created by an intrinsic magnetic field. Magnetospheres created due to this type of interaction are called induced magnetospheres (Cloutier & Daniell (1973), Cloutier& Daniell (1979), Luhman et al. (2004), Kivelson et al. (2007),Echer (2010) and Dieval et al. (2012)). The magnetosheath of such unmagnetized planets has typically an addition of a new population of planetary ions to the hydrogen magnetoplasma, which drastically alters the dispersion of hydromagnetic waves and can produce new types of MHD (Magneto- hydrodynamics) discontinuities in the transition region (Sauer et al. (1998)). The study of wave propagation is very important due to the fact that they have an important role in the energy and momentum transfer between the solar wind and the magnetosphere for example at Mars (Espley et al. (2004)). Consequently, these waves are related to the processes of atmospheric loss at Mars via interaction with the solar wind. Considering the importance to study waves in the Martian magnetosheath, the aim of this work is to determine the major frequency of electron oscillations in that region. 230 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S1743921317003672 Downloaded from https://www.cambridge.org/core. IP address: 54.70.40.11, on 18 Aug 2019 at 01:35:20, subject to the Cambridge Core terms of use, available at