Division E Commission 49: Interplanetary Plasma and Heliosphere

Abstract

Abstract. After a little more than forty years of work related to the interplanetary plasma and the heliosphere the IAU's Commission 49 was formally discontinued in 2015. The commission started its work when the first spacecraft were launched to measure the solar wind in-situ away from Earth orbit, both inward and outward from 1 AU. It now hands over its activities to a new commission during an era of space research when Voyager 1 measures in-situ the parameters of the local interstellar medium at the edge of the heliosphere. The commission will be succeeded by C.E3 with a similar area of responsibility but with more focused specific tasks that the community intends to address during the coming several years. This report includes a short description of the motivation for this commission and of the historical context. It then describes work from 2012 to 2015 during the present solar cycle 24 that has been the weakest in the space era so far. It gave rise to a large number of studies on solar energetic particles and cosmic rays. Other studies addressed e.g. the variation of the solar wind structure and energetic particle fluxes on long time scales, the detection of dust in the solar wind and the Voyager measurements at the edge of the heliosphere. The research is based on measurements from spacecraft that are at present operational and motivated by the upcoming Solar Probe + and Solar Orbiter missions to explore the vicinity of the Sun. We also report here the progress on new and planned radio instruments and their importance for heliospheric studies. Contributors to this report are

Challenges and Strategic Research Plans for Earth and Heliosphere: Research Infrastructures, Projects and Initiatives

“…Research to study of these phenomena started in the 1970's, when observations from space provided observational data of the solar corona and the interplanetary medium inside Earth orbit and the first space missions to the outer system were launched. As a result, the International Astronomical Union (IAU) devoted a new commission to the topic of heliospheric studies (described in a recent summary of the commissions history, Mann et al 2016). The first report of the new IAU commission pointed out that, in future, it would be useful to develop a capability for predicting, from solar observations, the state of the solar wind at the Earth (cf.…”