superconducting state takes place is $T_{c}=\Delta /1.76$, where $\Delta $ is the pairing gap energy [@Bl]. An early estimation of $\Delta $ gave $\Delta \sim
0.1-1$ MeV [@early], but some recent studies considering instanton-induced interactions between quarks estimated $\Delta
\sim 100$ MeV [@all1].

Strange quark matter in the color-flavor locked (CFL) phase of QCD, which occurs for $\Delta \sim 100$ MeV, could be rigorously electrically neutral, despite the unequal quark masses, even in the presence of the electron chemical potential [@all1]. Hence, for the CFL state of quark matter $V_q=0$ and no electrons are present inside or outside the quark star [@LH03].

However, @PaUs02 pointed out that for sufficiently large $m_{s}$ the low density regime is rather expected to be in the ”2-color-flavor Superconductor” phase in which only $u$ and $d$ quarks of two color are paired in single condensate while the ones of the third color, and $s$ quarks of all three colors, are unpaired. In this phase, some electrons are still present. In other words, electrons may be absent in the core of strange stars but present, at least, near the surface where the density is lowest. Nevertheless, the presence of the CFL effect can reduce the electron 