Astron. Astrophys. 326, 155-160 (1997)

Astron. Astrophys. 326, 155-160 (1997)

Bernoulli's equation and the contact binaries

John Hazlehurst

Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany

Received 31 May 1996 / Accepted 31 January 1997

Abstract

In a recent paper Bernoulli's equation has been so interpreted as to mean that the Jacobi energy is constant over the surface of a stationary contact binary. We argue that Bernoulli's result can not be interpreted in this way and show that such a constraint on the Jacobi energy is in general not compatible with stationarity.

We also show that, under isentropic conditions, a surface potential gradient can not cause a steady net flow of material across the system's surface plus a deeper return flow.

An apparent paradox raised by 'stationary solutions' for AB Andromedae can be resolved when it is recognized that Bernoulli's equation does not provide a simple recipe for calculating mean potential differences between contact components.

Key words: stars: binaries: close hydrodynamics

Send offprint requests to: John Hazlehurst (address above)

1. Introduction
2. Bernoulli's equation; preliminary remarks
3. The Jacobi energy assumption
4. The reversing-layer model
5. A differential-rotation test
6. Discussion of neglected effects
7. AB Andromedae
8. Conclusion
References

Online publication: April 20, 1998
helpdesk.link@springer.de

Bernoulli's equation and the contact binaries

Contents