Strange Star Surface: A Crust with Nuggets

We reexamine the surface composition of strange stars. Strange quark stars are hypothetical compact stars which could exist if strange quark matter was absolutely stable. It is widely accepted that they are characterized by an enormous density gradient (${10}^{26}\mathrm{g}/{\mathrm{cm}}^4$) and large electric fields at the surface. By investigating the possibility of realizing a heterogeneous crust, comprised of nuggets of strange quark matter embedded in an uniform electron background, we find that the strange star surface has a much reduced density gradient and negligible electric field. We comment on how our findings will impact various proposed observable signatures for strange stars.

Figure 1

The equation of state of the mixed phase. Inset shows the variation of the volume fraction of the quark phase as ${\mu }_e$ changes across the mixed phase.

Figure 2

Density profile of the crust for a strange star with mass $M=14M_{\odot }$ and radius $R=10\mathrm{km}$.