An effective double-layer stellar structure

A physically viable anisotropic double-layer structure compatible with the description of an effective double-layer stellar structure is constructed. For this aim, Einstein’s field equations of gravity for an anisotropic fluid joined to a linear equation of state related to quark matter and a quadratic equation of state related to exotic matter have been used to model the core and the envelope, respectively. Our findings reveal that this structure satisfies the dominant and strong energy conditions for an acceptable gravitational source, as well as having high stability with respect to the Harrison–Zeldovich–Novikov criterion, convection motion, gravitational cracking, and anti-collapse criteria. In this sense, this model can serve as a basis for later theoretical extensions, such as including electric charge, or, why not,the influence of the cosmological constant.