= E. Möbius
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<E. Möbius> is the first author of a 1985 study detecting interstellar <helium> after it became ionized and was carried into the <solar wind>. The observed <pickup ions> had a <velocity distribution> extending to approximately twice the solar-wind speed. The authors also related a seasonal increase in flux to <gravitational focusing> of neutral interstellar material downstream of the Sun.<Direct observation of He+ pick-up ions of interstellar origin in the solar wind by E. Möbius and others>[verified byline and abstract]{ref}
A related primary report describes the <time-of-flight mass spectrometry> used by a satellite instrument to observe energetic, singly ionized helium between September and December 1984. Measuring particle identity and energy makes the population distinguishable from the ordinary bulk <solar wind>; the interpretation then uses the shape of the observed spectrum.<Observation of pick-up ions in the solar wind: Evidence for the source of the anomalous cosmic ray component?>[abstract, SULEICA measurements and energy cutoff]{ref}
An idealized velocity argument explains the upper-speed scale. Let the <solar wind> move at speed $V$ relative to the Sun. An initially slow neutral atom becomes an <ion> with speed roughly $V$ in the wind's <reference frame>. If its velocity direction is redistributed while that magnitude remains similar, transforming back to the Sun's <reference frame> can produce speeds up to $2V$. This is a physical signature of pickup and acceleration, rather than an assertion that every detected ion moves at that maximum.
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