A period study of AR Lacertae
Chun‐Hwey Kim · The Astronomical Journal · 1991
Fifteen new times of minimum light are presented for AR Lac. Times of minimum light obtained between December 1982 and November 1986 confirm that the period of the system has decreased since the early 1960's. Three possible explanatory mechanisms are examined (abrupt changes of period due to mass transfer, a light-time effect due to a hypothetical third body, and anisotropic mass ejection), but none seem to explain the period variation. A conceptually new way of considering this variation.