Useful as standard candles as noted by Henrietta Leavitt, for 10 points, name this class of variable stars.
An early explanation for the behavior of these astronomical objects involved the existence of a conductive ionized-hydrogen zone capable of functioning as a heat engine; however, Eddington's model, also called the kappa-mechanism, provided insufficient energy absorption. Baker and Kippenhahn later demonstrated that helium ionization could serve as a viable mechanism for the characteristic properties of these entities. Hubble studied them in Andromeda and Triangulum to note that those galaxies were not part of the Milky Way. Unlike the similar RR Lyrae class, which are also found in the instability strip, stars in this class have a period ranging from 1 to 50 days. Useful as standard candles as noted by Henrietta Leavitt, for 10 points, name this class of variable stars.
An early explanation for the behavior of these astronomical objects involved the existence of a conductive ionized-hydrogen zone capable of functioning as a heat engine; however, Eddington's model, also called the kappa-mechanism, provided insufficient energy absorption.
{Cepheid} variables [accept variable stars before “RR”]