Heartbeat stars are binary star systems where each star travels in a highly elliptical orbit around the common mass center, and the distance between the two stars varies drastically as they orbit each other.Шаблон:R Heartbeat stars can get as close as a few stellar radii to each other and as far as 100 times that distance during one orbit.Шаблон:R As the star with the more elliptical orbit swings closer to its companion, gravity will stretch the star into a non-spherical shape, changing its apparent light output.Шаблон:R At their closest point in orbit, the tidal forces cause the shape of the heartbeat stars to fluctuate rapidly.Шаблон:R When the stars reach the point of their closest encounter, the mutual gravitational pull between the two stars will cause them to become slightly ellipsoidal in shape, which is one of the reasons for their observed brightness being so variable.Шаблон:R
Discoveries
Heartbeat stars were studied for the first time on the basis of OGLE project observations.Шаблон:R The Kepler Space Telescope with its long monitoring of the brightness off hundreds of thousands of stars enabled the discovery of many heartbeat stars. One of the first binary systems discovered to show the elliptical orbits, KOI-54, has been shown to increase in brightness every 41.8 days.Шаблон:R A subsequent study in 2012 characterized 17 additional objects from the Kepler data and united them as a class of binary stars.Шаблон:RШаблон:R
A study which measured the rotation rate of star spots on the surface of heartbeat stars showed that most heartbeat stars rotate slower than expected.Шаблон:R A study which measured the orbits of 19 heartbeat star systems, found that surveyed heartbeat stars tend to be both bigger and hotter than the Sun.Шаблон:R
The star HD 74423, discovered using NASA's Transiting Exoplanet Survey Satellite, was found to be unusually teardrop-shaped, which causes the star to pulsate only on one side, the first known heartbeat star to do so.Шаблон:R
