Departament d'Astronomia i Astrofísica
Universitat de València

    Solar Wind Interaction with the Local Interstellar Medium: Achievements and Challenges

N. V. Pogorelov

Physics Department and Center for Space Plasma and Aeronomic Research University of Alabama in Huntsville, USA

Seminari del departament d'Astronomia i Astrofísica

Dilluns 18 octubre 2010



From the astrophysical perspective, the solar wind (SW) interaction with the local interstellar medium (LISM) is a particular case of the flow around an ejecting star placed into surrounding medium. I will describe the mathematical and physical statements of this problem and demonstrate how the interstellar magnetic field shapes the astropause. While the Voyager 1 and 2 spacecraft are exploring the boundaries of the heliosphere, our newest spacecraft, the Interstellar Boundary Explorer (IBEX) has started exploring the outermost reaches of the heliosphere, but from an orbit at 1 AU measuring the fluxes of energetic neutral atoms (ENAs) created in the boundary regions separating the heliosphere from the LISM. The first IBEX results revealed a sky-spanning ribbon of unexpectedly intense emissions of ENAs that had not been predicted previously by any physical model. For the next 5-10 years, heliophysics research is faced with an extraordinary opportunity that cannot be soon repeated. This is to make in situ measurements of the SW from the Sun to the heliospheric boundaries and, at the same time, extract information about the global behavior of the evolving heliosphere through ENA observations by the IBEX. In this talk, the effects are described of unsteady SW and interstellar magnetic field (ISMF) pressure of the shape of the heliopause and the terminations shock. We analyze the ISMF influence on the deflection of the neutral hydrogen flow in the inner heliosphere from its original direction in the unperturbed LISM and on the position of the ENA ribbon. It is shown that the ISMF direction strongly correlates with the ribbon location, which is useful for constraining the properties of the interstellar medium in the immediate vicinity of the heliospheric boundary