Optical Time-series Photometry of the Symbiotic Nova V1835 Aquilae

We present time-series CCD photometry in the BVRI passbands of the recently identified symbiotic nova V1835 Aquilae (NSV 11749) over an interval of 5.1 yr with 7–14 day cadence, observed during its quiescence. We find slow light variations with a range of ∼0.9 mag in V and ∼0.3 mag in I. Analysis of these data show strong periodicity at 419 ± 10 days, which we interpret to be the system’s orbital period. A dip in the otherwise-sinusoidal phased light curve suggests a weak ellipsoidal effect due to tidal distortion of the giant star, which in turn opens the possibility that V1835 Aql transfers some of its mass to the hot component via Roche lobe overflow rather than via a stellar wind. We also find evidence that V1835 Aql is an S-type symbiotic star, relatively free of circumstellar dust, and include it among the nuclear burning group of symbiotics. Finally, we provide photometry, periods, and light curve classifications for 22 variable stars in the field around V1835 Aql, about half of which are newly identified.