Abstract:
We present the photometric and spectroscopic analysis of four W UMa binaries J015829.5+260333 (hereinafter as
J0158), J030505.1+293443 (hereinafter as J0305), J102211.7+310022 (hereinafter as J1022), and KW Psc. The
VRcIc band photometric observations are carried out with the 1.3 m Devasthal Fast Optical Telescope (DFOT). For
low-resolution spectroscopy, we used the 2 m Himalayan Chandra Telescope (HCT) as well as the archival data
from the 4 m LAMOST survey. The systems J0158 and J0305 show a period increase rate of
5.26( ± 1.72) × 10^−7 days yr^−1 and 1.78( ± 1.52) × 10^−6 days yr^−1, respectively. The period of J1022 is found
to be decreasing with a rate of 4.22 ( ± 1.67) × 10^−6 days yr^−1. The period analysis of KW Psc displays no change
in its period. The PHOEBE package is used for the light-curve modeling and basic parameters are evaluated with
the help of the GAIA parallax. The asymmetry of light curves is explained with the assumption of cool spots at
specific positions on one of the components of the system. On the basis of temperatures, mass ratios, fill-out
factors, and periods, the system J1022 is identified as a W-subtype system while the others show some mixed
properties. To probe the chromospheric activities in these W UMa binaries, their spectra are compared with the
known inactive stars’ spectra. The comparison shows emission in Hα, Hβ, and Ca II. To understand the
evolutionary status of these systems, the components are plotted in mass–radius and mass–luminosity planes with
other well characterized binary systems. The secondary components of all the systems are away from ZAMS,
which indicates that the secondary is more evolved than the primary component.
