Estimation of the neon/oxygen abundance ratio at the heliospheric termination shock and in the local interstellar medium from IBEX observations

P. Bochsler, L. Petersen, E. Möbius, N. A. Schwadron, P. Wurz, J. A. Scheer, S. A. Fuselier, D. J. McComas, M. Bzowski, P. C. Frisch

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

We report the first direct measurement of the Ne/O abundance ratio of the interstellar neutral gas flowing into the inner heliosphere. From the first year of Interstellar Boundary Explorer IBEX data collected in spring 2009, we derive the fluxes of interstellar neutral oxygen and neon. Using the flux ratio at the location of IBEX at 1AU at the time of the observations, and using the ionization rates of neon and oxygen prevailing in the heliosphere during the period of solar minimum, we estimate the neon/oxygen ratios at the heliospheric termination shock and in the gas phase of the inflowing local interstellar medium. Our estimate is (Ne/O) gas, ISM = 0.27 ± 0.10, which is - within the large given uncertainties - consistent with earlier measurements from pickup ions. Our value is larger than the solar abundance ratio, possibly indicating that a significant fraction of oxygen in the local interstellar medium is hidden in grains and/or ices.

Original languageEnglish (US)
Article number13
JournalAstrophysical Journal, Supplement Series
Volume198
Issue number2
DOIs
StatePublished - Feb 1 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • ISM: abundances
  • ISM: atoms
  • Sun: heliosphere

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