V2653 Ophiuchii with a pulsating component and Ppuls-Porb, Ppuls-g correlations for gamma-Dor type pulsators

We present new spectroscopic observations of the double-lined eclipsing binary V2653\,Oph. The photometric observations obtained by $ASAS$ were analysed and combined with the analysis of radial velocities for deriving the absolute parameters of the components. Masses and radii were determined for the first time as M$_p$=1.537$\pm$0.021 M$_{\odot}$ and R$_p$=2.215$\pm$0.055 R$_{\odot}$, M$_s$=1.273$\pm$0.019 M$_{\odot}$ and R$_s$=2.000$\pm$0.056 R$_{\odot}$ for the components of V2653\,Oph. We estimate an interstellar reddening of 0.15$\pm$0.08\,mag and a distance of 300$\pm$50\,pc for the system, both supporting the membership of the open cluster Collinder\,359. Using the out-of-eclipse photometric data we have made frequency analysis and detected a periodic signal at 1.0029$\pm$0.0019\,c/d. This frequency and the location of the more massive star on the HR diagram lead to classification of a $\gamma$ Dor type variable. Up to date only eleven $\gamma$ Dor type pulsators in the eclipsing binaries have been discovered. For six out of 11 systems, the physical parameters were determined. Although a small sample, we find empirical relations that $P_{puls}$ $\propto$ $P_{orb}^{0.43}$ and $P_{puls}$ $\propto$ $g^{-0.83}$. While the pulsation periods increase with longer orbital periods, they decrease with increasing surface gravities of pulsating components and gravitational pull exerted by the companions. We present, briefly, the underlying physics behind