Temporal measurements of the interstellar helium focusing cone by the Magnetospheric Multiscale Mission(MMS) | CU Experts

; <p>The Sun and its associated heliosphere travels through the local interstellar medium (LISM) at 26 km/s.&#160; This results in a flow of neutral particles constantly entering the heliosphere at the same velocity.&#160; Neutral atoms with trajectories close to the Sun, which survive its ionizing radiation environment, become gravitationally attracted to it resulting in a focusing cone, a region of enhanced neutral density, downwind of the Sun.&#160; The increased neutral density in these regions leads to a higher density of pickup ions created by charge-exchange of the neutrals.&#160; In near-Earth orbit, the Magnetospheric Multiscale spacecraft (4 in all) have orbital apogees on the dayside during Earth&#8217;s annual encounter with the helium focusing cone (from mid-November to mid-December).&#160; Since launching in March of 2015, regular acquisitions with the Hot Plasma Composition Analyzers (HPCAs) have been conducted, with acquisitions from 2017 through 2019 occurring with a 29 RE apogee, ensuring long intervals in the pristine Solar Wind.&#160;&#160; We provide measurements of the focusing cone during the declining phase of the previous solar cycle. These measurements are used to investigate the effect of solar radiation on the focusing cone.</p>;

Gomez R; Fuselier S; Burch J; Mukherjee J; Gonzalez C; Trattner K; Starkey M; Strangeway R

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