Heartbeat Star

A Heartbeat Star ( German  heartbeat Star ) is a stellar pulsations , whose vibrations through tidal forces are excited. The name Heartbeat comes from a similarity between the light curve of the variable star and the course of the heartbeat in an electrocardiogram . Many well-known Heartbeat Stars were discovered with the Kepler telescope .

description

In Heartbeat stars is a binary star system in which the components on a highly elliptical orbit rotating around a common center of mass. The perihelion distance is only a few star radii and so tidal forces can stimulate vibrations in one or both stars at the time of the perihelion. Due to the tidal forces, the stars take on an ellipsoidal shape, whereby after the perihelion the restoring forces due to the gas pressure and gravity bring the star back into a spherical shape. Since the star's atmosphere still has a finite speed in the spherical shape , the star oscillates again into an ellipsoidal shape. With each oscillation, the amplitude decreases due to the viscosity until a new near transition in the binary star system stimulates the oscillations again. The amplitudes in the light curves are very small and amount to a few hundred parts per million . The orbital periods of the double stars are harmonics of the basic oscillation of the stars, since only resonance effects lead to a measurable amplitude of the pulsations.

In many systems, the mass of the companion can be calculated using the radial velocity method , provided that the mass of the primary star is known.

Examples

• KOI-54
• Iota Orionis

See also

• Ellipsoid variable star

Web links

https://www.nasa.gov/feature/jpl/heartbeat-stars-unlocked-in-new-study

literature

• William F. Welsh at al .: KOI-54: The Kepler Discovery of Tidally-Excited Pulsations and Brightenings in a Highly Eccentric Binary . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1102.1730v1 (English).
• Susan E. Thompson et al .: A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1203.6115v1 (English).
• M. Hareter, M. Paparó: CoRoT target HD 51844: a delta Scuti star in a binary system with periastron brightening . In: Astrophysics. Solar and Stellar Astrophysics . 2013, arxiv : 1309.4314v1 (English).

Individual evidence

1. ↑ Avi Shporer et. all: Radial Velocity Monitoring of Kepler Heartbeat Stars . In: The Astrophysical Journal . Vol. 829, No. 1 , 2016, doi : 10.3847 / 0004-637X / 829/1/34 (English).