We present a study of blue straggler stars (BSSs) of open cluster NGC 7142
using AstroSat/UVIT data and other archival data. Using a machine
learning-based algorithm, ML-MOC, on Gaia DR3 data, we find 546 sources as
cluster members. Based on the location on the Gaia color-magnitude diagram, we
identify ten BSS candidates, also detected in UVIT/F148W filter. We study the
variable nature of BSSs by constructing their light curves using the TESS data.
Two BSSs reported as eclipsing binaries in Gaia DR3 are confirmed to be
eclipsing binaries based on our analysis and also show the presence of hot
companions as per the multi-wavelength spectral energy distributions (SEDs).
The physical parameters of the hot companions of these two BSSs derived by
fitting binary models to their light curves and those derived from the SEDs are
found to be in good agreement. Additionally, five more BSSs in the cluster
shows UV excess, four of which are likely to have a hot companion based on
SEDs. The hot companions with the estimated temperatures βΌ14000 β 28000
K, radii βΌ0.01 β 0.05 Rββ, and luminosities βΌ0.03 β 0.1
Lββ, are inferred to be extremely low mass (< 0.2 Mββ),
low-mass (0.2 β 0.4 Mββ), normal-mass (0.4 β 0.6 Mββ), and
high-mass (> 0.6 Mββ) white dwarfs (WD). For the first time in an
open cluster, we find the entire range of masses in WDs found as hot companions
of BSSs. These masses imply that the Case-A/Case-B mass transfer as well as
merger are responsible for the formation of at least 60% of the BSSs of this
cluster