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Start Over Author "V. Demmel" Topic astrophysics::high energy astrophysical phenomena
2 results on '"V. Demmel"'

1. Deterministic chaos in a discrete-time model for spherical accretion onto neutron stars

Author

Harald Atmanspacher, V. Demmel, and Gregor E. Morfill

Subjects
Physics, Atmospheric Science, Astrophysics::High Energy Astrophysical Phenomena, Chaotic, Aerospace Engineering, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Radiation, Accretion (astrophysics), Accretion rate, Nonlinear system, Neutron star, Geophysics, Discrete time and continuous time, Dynamic models, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The interaction of the accreting mass and the X-ray radiation of a spherically accreting neutron star is described by a discrete — time dynamical model. Its main feature consists of a nonlinear feedback mechanism between mass accretion and escaping radiation. The model is studied with respect to its stability properties and its astrophysical implications. As a function of time, we obtain stationary, periodic, and chaotic luminosities. The different kinds of behavior occur in different regimes of the mass accretion rate.

Published
1988

2. A model for spherically symmetric accretion onto neutron stars

Author

V. Demmel, Gregor E. Morfill, and Harald Atmanspacher

Subjects
Physics, Astrophysics::High Energy Astrophysical Phenomena, Time evolution, X-ray binary, Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Plasma, Radiation, Accretion (astrophysics), symbols.namesake, Neutron star, Phenomenological model, Eddington luminosity, symbols, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present a phenomenological model of spherically accreting neutron stars at high mass accretion rates. The radiation and the optically thick plasma are described as two interacting fluids. The time evolution of the regarded system is calculated by a discrete time iteration map. It is shown, that the neutron star in our model may well exceed the Eddington luminosity.

Published
1989

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