Kinetic modelling of primary and secondary interstellar oxygen atom fluxes in the heliosphere

[摘要] The interstellar neutral (ISN) oxygen atoms penetrate into the heliosphere from the Local Interstellar Medium (LISM). Oxygen atoms that directly penetrate into the heliosphere are called primary, while secondary oxygen population is formed near the heliopause due to the process of charge exchange of interstellar oxygen ions with hydrogen atoms and its existence in the heliosphere was previously predicted theoretically (Izmodenov et al., 1997, 1999, 2004). In this work we study the distribution of both primary and secondary oxygen atoms in the heliosphere and its fluxes at 1 AU. The analysis of the distribution of ISN O atoms in the heliosphere is only possible in the frame of a model that takes into account both filtration of the primary and origin of the secondary interstellar oxygen in the region of interaction of the solar wind (SW) with the LISM, as well as a detailed simulation of the motion of interstellar atoms inside the heliosphere. This simulation should take into account the temporal and heliolatitudinal dependences of ionization, the process of charge exchange with SW protons and the effect of the solar gravitational attraction. This paper presents the results of modelling ISN O atoms inside the heliosphere based on a new three-dimensional kinetic-MHD model of the SW interaction with the LISM (Izmodenov and Alexashov, 2015). Oxygen atoms are of a particular interest because they are strongly coupled with the protons through the charge exchange process and due to the fact that the fluxes of interstellar oxygen are directly measured by the Interstellar Boundary Explorer (IBEX). The first quantitative measurements of the interstellar heavy neutral atoms (O and Ne) obtained on the IBEX spacecraft were presented in (Park et al., ApJS, 2015). Qualitative analysis of these data shows that the secondary component of the interstellar oxygen atoms was also measured along with the primary interstellar atoms.

[发布机构] Space Research Institute of Russian Academy of Sciences, Profsoyuznaya Str. 84/32, Moscow; 117335, Russia^1;Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow; 119991, Russia^2;A. Ishlinsky Institute for Problems in Mechanics, prosp. Vernadskogo 101, Moscow; 119526, Russia^3

[效力级别] 力学 [学科分类] 力学，机械学

[关键词] Charge exchange process;Charge exchanges;Gravitational attraction;Kinetic modelling;Local interstellar medium;Qualitative analysis;Quantitative measurement;Secondary components