zero age horizontal branch star (ZAHB)
setâre-ye šâxe-ye ofoqi bâ senn-e sefr
Fr.: étoile de la branche horizontale d'âge zéro
ZZ Ceti star
setâre-ye ZZ Ketus
Fr.: étoile de type ZZ Ceti
A member of a class of non-radially pulsating stas that change their brightnesses with periods from 30 seconds to 25 minutes and amplitudes from 0.001 to 0.2 mag in V. Their location on the → Hertzsprung-Russell diagram identifies them as → white dwarf stars that have entered the → instability strip as they evolve along the white dwarf track.