Interstellar gas flow vector and temperature determination over 5 years of IBEX observations

E. Möbius, M. Bzowski, S. A. Fuselier, D. Heirtzler, M. A. Kubiak, H. Kucharek, M. A. Lee, T. Leonard, D. J. McComas, N. Schwadron, J. M. Sokół, P. Wurz

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Abstract

The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by 3° and lower by 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere.

Original languageEnglish (US)
Article number012019
JournalJournal of Physics: Conference Series
Volume577
Issue number1
DOIs
StatePublished - 2015
Event13th Annual International Astrophysics Conference: Voyager, IBEX, and the Interstellar Medium, AIAC 2014 - Myrtle Beach, United States
Duration: Mar 10 2014Mar 14 2014

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Möbius, E., Bzowski, M., Fuselier, S. A., Heirtzler, D., Kubiak, M. A., Kucharek, H., Lee, M. A., Leonard, T., McComas, D. J., Schwadron, N., Sokół, J. M., & Wurz, P. (2015). Interstellar gas flow vector and temperature determination over 5 years of IBEX observations. Journal of Physics: Conference Series, 577(1), [012019]. https://doi.org/10.1088/1742-6596/577/1/012019