EDP Sciences
Free access
Issue
A&A
Volume 414, Number 3, February II 2004
Page(s) L29 - L32
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20031697


A&A 414, L29-L32 (2004)
DOI: 10.1051/0004-6361:20031697

Letter

Filtration of interstellar H, O, N atoms through the heliospheric interface: Inferences on local interstellar abundances of the elements

V. Izmodenov1, Y. Malama2, G. Gloeckler3 and J. Geiss4

1  Lomonosov Moscow State University, Department of Aeromechanics and Gas Dynamics, Faculty of Mechanics and Mathematics, Moscow 119899, Russia
2  Institute for Problems in Mechanics, Russian Academy of Sciences, Prospect Vernadskogo 101-1, Moscow 117526, Russia
3  Department of Physics and IPST, University of Maryland, College Park, Maryland 20742, USA
    e-mail: gg10@umail.umd.edu
4  International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
    e-mail: geiss@issi.unibe.ch

(Received 16 October 2003 / Accepted 27 November 2003)

Abstract
In this Letter we report on our study of the filtration of interstellar atoms of hydrogen, oxygen and nitrogen in the interaction region between the solar wind and the local interstellar medium. The filtration has great importance for the determination of local interstellar abundances of these elements, which becomes now possible due to measurements of interstellar pickup ions by Ulysses and ACE, and anomalous cosmic rays by Voyagers, Ulysses, ACE, SAMPEX and Wind. The filtration of the different elements depends on the level of their coupling with the plasma in the interaction region. We study the dependence of the filtration on the local interstellar proton and H atom number densities and evaluate the effects of charge exchange and electron impact ionization on the filtration. We explore the influence of electron temperature in the inner heliosheath on the filtration process. Using our filtration coefficients and SWICS/Ulysses pickup ion measurements we conclude $n_{\rm OI,LIC}=(7.8 \pm
1.3)\times 10^{-5}$ cm -3 and $n_{\rm NI,LIC}=(1.1 \pm
0.2)\times 10^{-5}$ cm -3.


Key words: Sun: solar wind -- interplanetary medium -- ISM: atoms

Offprint request: V. Izmodenov, izmod@ipmnet.ru




© ESO 2004