Illustration of a binary star system where the gravitational pull of one of the stars is causing the other into a teardrop shape. The stars are tidally locked so that the same face of the star at left is always facing the star at right. This constant gravitational pull on one face of the star causes pulsations, which are usually uniform over a star's surface, to only occur on the side facing the other star. The discovery of the first star system containing a teardrop-shaped star was published in March 2020. The star, HD74423, was found in data from NASA's Transiting Exoplanet Survey Satellite (TESS) satellite.