Deep MMT Transit Survey of the Open Cluster M37 II: Variable Stars

We have conducted a deep ($15\text{la}r\text{la}23$), 20 night survey for transiting planets in the intermediate age ($\sim 550\mathrm{M}\mathrm{y}\mathrm{r}$) open cluster M37 (NGC 2099) using the Megacam wide-field mosaic CCD camera on the 6.5m Multiple Mirror Telescope (MMT). In this paper we present a catalog and light curves for 1445 variable stars; 1430 (99%) of these are new discoveries. We have discovered 20 new eclipsing binaries and 31 new short period ($P < 1 {\rm day}$) pulsating stars. The bulk of the variables are most likely rapidly rotating young low-mass stars, including a substantial number ($\text{ga}500$) that are members of the cluster. We identify and analyze five particularly interesting individual variables including a previously identified variable which we suggest is probably a hybrid $\gamma$ Doradus/$\delta$ Scuti pulsator, two possible quiescent cataclysmic variables, a detached eclipsing binary (DEB) with at least one $\gamma$ Doradus pulsating component (only the second such variable found in an eclipsing binary), and a low mass ($M_{P} \sim M_{S} \sim 0.6 M_{\odot}$) DEB that is a possible cluster member. A preliminary determination of the physical parameters for the DEB+$\gamma$ Doradus system yields $M_P=1.58\pm 0.04M_{\odot }$, $M_S=1.58\pm 0.04M_{\odot }$, $R_P=1.39\pm 0.07R_{\odot }$ and $R_S=1.38\pm 0.07R_{\odot }$.