1. Close binary systems Jean-Pierre Lasota Lecture 4 Accretion discs I

4. Accretion disc formation in a binary system

5. Eclipsing binary allow observing elements of the accretion configuration

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10. ingress egress

11. For stationary, Keplerian discs the effective T varies like Brightness temperature Stationary, Keplerian discs do exist !

12. This is a non-stationary accretion disc; dwarf nova at minimum light

13. Double emission lines: result of differential (Keplerian rotation).

15. Doppler tomography

16. Magneto-Rotational Instability (MRI) creates turbulence in Keplerian accretion discs Higher velocity; lower angular mom. lower velocity; higher angular mom. (weak) magn. field This is unstable and transports ang. mom. outwards, i.e. allows accretion.

17. f=0 Epicyclic frequency Oscillator analogue: There exist solutions representing unstable modes

18. : Radial equations for a Keplerian accretion disc 1. Mass-conservation (continuity) equation: 2. Angular momentum conservation equation: Tidal torque

19. 3. Momentum conservation Euler (equation) 4. Energy conservation equation - mid-plane temperature,