Close binary systems Jean-Pierre Lasota Lecture 1

Close binary systemsJean-Pierre Lasota

Lecture 1

he light curve of Persei (Algol) – an eclipsing close binary

Al Ghoul

Persei

Doppler effect in stellar spectra.

Ellipsoidal variations

See in Lasota, Scientific American, 280, part no 5, 40-47 (1999)

Sizes

Tycho’s Nova (in fact a Supernova of type Ia – both novae and SNIa appear in close binaries containing white dwarfs.

a Nova outburst a Nova outburst

The structure of a close binary

A black-hole low-mass X-ray binary

Outflows

A black-hole in a high-mass X-ray binary

Eclipsing X-ray binaries are very rare

Dip

Eclipse

Dips

Types of close binary systemsTypes of close binary systems

Equipotential surfaces in Roche geometry

- Euler equation

- Roche potential

. .1 2

Roche lobesRoche lobes

Flow of matter on the irradiated surface of a Roche-lobe filling star

Coriolis frequency Rossby number

V, L – velocity & length scales

When << 1 geostrophic flow: rotation important

Most close binaries have small eccentricities. This is not true of planets

Binary type Compact object Donor Comment

Cataclysmic binariesCataclysmic binaries White dwarf Red dwarfSubtypes : dwarf novae, novae

AM CVn binaryAM CVn binaryWhite dwarf White dwarf No H

Super Soft X-ray SourcesSuper Soft X-ray Sources White dwarf GiantSupersoft X soucres could be progenitors of SN Ia

Ultracompact X-ray BinariesUltracompact X-ray Binaries Neutron star White dwarf Shortest binary period: 11 min.

Low Mass X binariesLow Mass X binaries Neutron star or black holeM, K, G, F dwarfs or ou subgiants

All black hole X-ray binaries are transient

High Mass X-ray binariesHigh Mass X-ray binaries Neutron star or black hole

0,B type supergiants or subgiants

The neutron star is often an X-ray pulsar

Gamma-ray binariesGamma-ray binaries Neutron star (pulsar) Supergiant Driven by rotation