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Title: ESTIMATION OF THE NEON/OXYGEN ABUNDANCE RATIO AT THE HELIOSPHERIC TERMINATION SHOCK AND IN THE LOCAL INTERSTELLAR MEDIUM FROM IBEX OBSERVATIONS

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 1 AU 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){sub 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.

Authors:
; ; ;  [1]; ;  [2];  [3];  [4];  [5]
  1. Space Science Center and Department of Physics, University of New Hampshire, 8 College Road, Durham, NH 03824 (United States)
  2. Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)
  3. Lockheed Martin Advanced Technology Center, 3251 Hanover St., Palo Alto, CA 94304 (United States)
  4. Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238 (United States)
  5. Space Research Centre, Polish Academy of Sciences, Bartycka 18 A, PL 00-716 Warsaw (Poland)
Publication Date:
OSTI Identifier:
22048042
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal, Supplement Series
Additional Journal Information:
Journal Volume: 198; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0067-0049
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; ATOMS; COSMIC GASES; ELEMENT ABUNDANCE; HELIOSPHERE; ICE; INTERSTELLAR SPACE; IONIZATION; IONS; NEON; OXYGEN; SUN

Citation Formats

Bochsler, P, Petersen, L, Moebius, E, Schwadron, N A, Wurz, P, Scheer, J A, Fuselier, S A, McComas, D J, Bzowski, M, and Frisch, P. C., E-mail: bochsler@space.unibe.ch. ESTIMATION OF THE NEON/OXYGEN ABUNDANCE RATIO AT THE HELIOSPHERIC TERMINATION SHOCK AND IN THE LOCAL INTERSTELLAR MEDIUM FROM IBEX OBSERVATIONS. United States: N. p., 2012. Web. doi:10.1088/0067-0049/198/2/13.
Bochsler, P, Petersen, L, Moebius, E, Schwadron, N A, Wurz, P, Scheer, J A, Fuselier, S A, McComas, D J, Bzowski, M, & Frisch, P. C., E-mail: bochsler@space.unibe.ch. ESTIMATION OF THE NEON/OXYGEN ABUNDANCE RATIO AT THE HELIOSPHERIC TERMINATION SHOCK AND IN THE LOCAL INTERSTELLAR MEDIUM FROM IBEX OBSERVATIONS. United States. doi:10.1088/0067-0049/198/2/13.
Bochsler, P, Petersen, L, Moebius, E, Schwadron, N A, Wurz, P, Scheer, J A, Fuselier, S A, McComas, D J, Bzowski, M, and Frisch, P. C., E-mail: bochsler@space.unibe.ch. Wed . "ESTIMATION OF THE NEON/OXYGEN ABUNDANCE RATIO AT THE HELIOSPHERIC TERMINATION SHOCK AND IN THE LOCAL INTERSTELLAR MEDIUM FROM IBEX OBSERVATIONS". United States. doi:10.1088/0067-0049/198/2/13.
@article{osti_22048042,
title = {ESTIMATION OF THE NEON/OXYGEN ABUNDANCE RATIO AT THE HELIOSPHERIC TERMINATION SHOCK AND IN THE LOCAL INTERSTELLAR MEDIUM FROM IBEX OBSERVATIONS},
author = {Bochsler, P and Petersen, L and Moebius, E and Schwadron, N A and Wurz, P and Scheer, J A and Fuselier, S A and McComas, D J and Bzowski, M and Frisch, P. C., E-mail: bochsler@space.unibe.ch},
abstractNote = {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 1 AU 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){sub 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.},
doi = {10.1088/0067-0049/198/2/13},
journal = {Astrophysical Journal, Supplement Series},
issn = {0067-0049},
number = 2,
volume = 198,
place = {United States},
year = {2012},
month = {2}
}