  In this paper, the equation of state (EOS) of deconfined quark stars is
studied in the framework of the two-flavor NJL model, and the self-consistent
mean field approximation is employed by introducing a parameter $\alpha$
combining the original Lagrangian and the Fierz-transformed Lagrangian,
$\mathcal{L}_R= (1-\alpha)\mathcal{L}+\alpha\mathcal{L}_F$, to measure the
weights of different interaction channels. It is believed that the
deconfinement of phase transition happens along with the chiral phase
transition. Thus, due to the lack of description of confinement in the NJL
model, the vacuum pressure is set to confine quarks at low densities, which is
the pressure corresponding to the critical point of chiral phase transition. We
find that deconfined quark stars can reach over two-solar-mass, and the bag
constant therefore shifts from $(130 ~\mathrm{MeV})^4$ to $(150
~\mathrm{MeV})^4$ as $\alpha$ grows. In addition, the tidal deformability
$\Lambda$ is yielded ranging from 253 to 482 along with the decrease of
$~\alpha$, which satisfies the astronomical constraint of $\Lambda<800$ for
1.4-solar-mass neutron stars.
