STEREO/PLASTIC: To boldly look where no man has looked before

23.01.2015

Christian Drews, PhD student in Prof. Dr. Wimmer-Schweingrubers group, together with Dr. L. Berger, have, for the first time, identified the so-called Ne+ cone inside the heliosphere at 1 AU. This observation provides clear evidence for the interstellar origin of neutral neon in the inner heliosphere. Their work has just been published in the Journal of Geophysical Research (C. Drews, 2010). Although theory has predicted the existence of a He+ and Ne+ cone since 1974, technical limitation prevented a verification of it's existence until 1985 for He+ (E. Moebius et al., 1985) and until 2010 for Ne+ (C. Drews, 2010)

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The observation of the Ne+ cone were made using the PLasma and SupraThermal Ion Composition instrument (PLASTIC) on-board the two STEREO spacecraft and it's capability of measuring even the least abundant ions with sufficient statistics (e.g. Ne+, which is several orders of magnitude less abundant than solar wind protons or even interstellar He+).

Thus, PLASTIC allows for the first time for a detailed analysis of the dynamics and properties of Ne+ ions, which act as a sample for it's interstellar neutral predecessors and provide a direct sample of the interstellar medium. In the future, this observation will help us to provide new insights into the interstellar medium surrounding our heliosphere.