 |
 |
Astron. Astrophys. 344, 317-321 (1999)
Interstellar oxygen in the heliospheric interface: influence of electron impact ionization
V.V. Izmodenov * 1,2,
R. Lallement 1 and
J. Geiss 2
1 Service d'Aeronomie, CNRS, F-91371 Verrieres le Buisson, France (Vlad.Izmodenov; Rosine.Lallement@aerov.jussieu.fr)
2 International Space Science Institute, Bern, Switzerland (johannes.geiss@issi.unibe.ch)
Received 3 November 1998 / Accepted 7 December 1998
Abstract
A fraction of the interstellar atoms crosses the interface between the solar wind and the ionized component of the local interstellar medium (the heliospheric interface), and enters the heliosphere. The number of penetrating atoms depends on the strength of the atom-plasma interaction, i.e. on the atom type.
In this paper we consider the penetration of the interstellar
oxygen atoms, and we study in detail the influence of the electron
impact ionization. It is shown that this process leads to a
significant interstellar O-atom density decrease in the heated (by the
termination shock) solar wind. A comparison between oxygen and
hydrogen shows that in the heliosphere these two elements have
abundances, temperatures and velocities that differ from the
corresponding interstellar parameters. On the basis of these new model
results, we compare the interstellar OI/HI ratio measured by the HST
with the ratio inside the heliosphere which can be deduced from
SWICS/Ulysses ![[FORMULA]](img1.gif)
and
![[FORMULA]](img2.gif)
pick-up data.
Key words: methods:
numerical 
atomic
processes
hydrodynamics
Sun: solar wind
ISM: atoms
ISM: abundances
* Permanently at Moscow State University, Department of Aeromechanics and Gas dynamics, Faculty of Mechanics and Mathematics (izmod@ipmnet.ru)
Send offprint requests to: V. Izmodenov
This article contains no SIMBAD objects.
Contents
- 1. Introduction
- 2. Model
- 3. Results of model calculations
- 4. Comparison of OI/HI interstellar and heliospheric ratios
- 5. Conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1999
Online publication: March 10, 1999
helpdesk.link@springer.de