LOCAL INTERSTELLAR NEUTRAL HYDROGEN SAMPLED IN SITU BY IBEX
- Space Research and Planetary Sciences, University of Bern, Bern (Switzerland)
- Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH (United States)
- Space Science Centre PAS, Warsaw (Poland)
- Lockheed Martin Advanced Technology Center, Palo Alto, CA (United States)
- Haystack Observatory, Massachusetts Institute of Technology, MA (United States)
- Southwest Research Institute, San Antonio, TX (United States)
Hydrogen gas is the dominant component of the local interstellar medium. However, owing to ionization and interaction with the heliosphere, direct sampling of neutral hydrogen in the inner heliosphere is more difficult than sampling the local interstellar neutral helium, which penetrates deep into the heliosphere. In this paper, we report on the first detailed analysis of the direct sampling of neutral hydrogen from the local interstellar medium. We confirm that the arrival direction of hydrogen is offset from that of the local helium component. We further report the discovery of a variation of the penetrating hydrogen over the first two years of Interstellar Boundary Explorer observations. Observations are consistent with hydrogen experiencing an effective ratio of outward solar radiation pressure to inward gravitational force greater than unity ({mu} > 1); the temporal change observed in the local interstellar hydrogen flux can be explained with solar variability.
- OSTI ID:
- 22048043
- Journal Information:
- Astrophysical Journal, Supplement Series, Vol. 198, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0067-0049
- Country of Publication:
- United States
- Language:
- English
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