Long-term photometric behavior of V404 Lyr

For the orbital inclinations i_4_>~43{deg}, the fourth component has a mass within the hydrogen-burning limit of ~0.07M_{sun}_, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary.

Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a {gamma} Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11/day with amplitudes of 1.38-5.72mmag and pulsation constants of 0.24-0.27days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be excited through tidal interaction.

Only eight eclipsing binaries have been known to contain {gamma} Dor pulsating components and, therefore, V404 Lyr will be an important test bed for investigating these rare and interesting objects.