X-ray and optical observations of two AM Her type cataclysmic variables: V388 Peg and V1189 Her

Abstract

We present time-resolved photometry of a polar V388 Peg and a strong candidate polar V1189 Her observed by T100 telescope at TÜBİTAK National Observatory between June–August 2014 and their X-ray observations using Swift archival data obtained in Apr 2014 (V388 Peg) and in Nov 2011 (V1189 Her). These data were supplemented by archival CRTS, ZTF, ASAS-SN, and ATLAS survey data which show frequent changes between high and low states. This study aims to obtain the temporal behaviors of two systems using the optical light curves and the X-ray spectral properties. The orbital periods of systems are corrected using photometric observations. Results obtained from light curves morphology related to accretion region are discussed for each system. V388 Peg shows a higher amplitude (∼1.6 mag) of orbital modulation and smooth structure in T100 optical observations. It is detected in X-rays at an unabsorbed flux (0.3–10 keV) of 3.6×10−12 erg cm−2 s−1 using a simple model of 30 keV bremsstrahlung model and the model-dependent corresponding luminosity is logL=32.3 erg s−1. The X-ray spectra of V1189 Her is fitted by a bremsstrahlung model and the estimated X-ray luminosity is found to be an order of magnitude lower than the 1032 erg s−1 typical of previously known polars. Using Gaia EDR3 distances, the information obtained from the X-ray spectral analysis and MWD∼0.7M⊙ for both sources, we estimate the mass accretion rates of ∼10−11M⊙ yr−1 (V388 Peg) and ∼10−12M⊙ yr−1 (V1189 Her). As a result of our study, it seems that these two systems have lower mass accretion rates than the long-term accretion rate that is driven by secular evolution, and considering their orbital periods this makes them interesting evolutionary test samples for polars.