Interpretation of the anomalous eclipse-timing variations in V736 And

Determine the physical origin of the anomalous eclipse-timing variations in V736 And, in which the dominant eclipsing pair A exhibits a large timing-variation amplitude while the shallower pair B shows essentially no comparable variation, contrary to the classical 2+2 quadruple light-travel-time interpretation.

Background

V736 And is presented as a doubly eclipsing system containing two short-period, apparently contact eclipsing binaries. The long-term timing analysis detects substantial eclipse-timing variations for pair A, with deviations of approximately 3% of its orbital period, whereas pair B remains nearly constant.

Under the classical interpretation of a gravitationally bound 2+2 quadruple, the two binaries orbit a common barycentre and should exhibit eclipse-timing variations with opposite shapes. Moreover, the observed luminosity dominance of pair A would lead one to expect its timing amplitude to be smaller rather than larger. The paper therefore leaves the physical interpretation of this discrepancy unresolved, with possible explanations discussed later including dynamical interactions, light-curve asymmetries, and a more complex multiple-star architecture.