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Submitted on 1 Jan 1979
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DECELERATION OF A FAST ION IN AN ACCRETION COLUMN
J. Kirk
To cite this version:
J. Kirk. DECELERATION OF A FAST ION IN AN ACCRETION COLUMN. Journal de Physique
Colloques, 1979, 40 (C7), pp.C7-705-C7-705. �10.1051/jphyscol:19797341�. �jpa-00219335�
JOURNAL DE PHYSIQUE CoZZoque C7, strppZdment au n07, Tome 40, J u i Z Z e t 1979, page C7- 705
DECELERATION OF A FAST ION IN AN ACCRETION COLUMN
J.G. Kirk.
Max-PZanck-Institut fiir P h y s i k und A s t r o p h y s i k , F8hringer Ring 6, 8 Winchen 40, FRG.
Calculations of the rate of energy depos- References
ition by a fast ion falling through the Alme, M.L. and Wilson, J.R. 1973 Astrophp.
plasma above a magnetised neutron star are J.
186,
1015important in the physics of X-ray Pulsarsf Basko, M.M. and Syunyaev, R.A. 1975
sov.
since they play a decisive role in the Phys. JETP
41,
52question of the formation of a stand-off Pavlov, G.G. and Yakovlev, D.G. 1976 sov.
shock front. Treatments of spherically Phys. JETP
43,
489symmetric accretion (Alme and Wilson, 1973) used the formula for deceleration by Cou- lomb collisions in the absence of a mag- netic field. This approach requires modifi- cation when a magnetised neutron star is considered. Basko and Syunyaev (1975) and Pavlov and Yakovlev (1 976) calculated the relevant cross-sections, and estimated that the stopping length of an ion is in- creased by an order of magnitude over the zero-field case. However, this conclusion no longer holds when the collective effects in the plasma are included. The most import of these is the scattering of the test ion off the ion-sound waves. That such a scat- tering can occur is seen only when full account is taken of the orbit of the ion in the magnetic field. Even a modest level of ion-sound turbulence suffices to deflect the ion, and severely reduce the stopping length. Computer calculations of the energy and momentum deposition rates in- clbding this new effect are in progress, and it is hoped that the results will indi- cate whether or not a non-radiative shock
can occur.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797341
