Massive spheres with an isothermal core

Massive spherical configurations with an isothermal core and an inverse-square variation of density in the envelope has been studied. It is found that such structures are pulsationally stable. Keeping in view the relativistic restriction on the speed of a signal (upsilonsub(s) <= c), it is found that Ksub(max) = 0.80 for such structures. The maximum surface and central red shifts are found to be 0.502 and 28.7 respectively. An application of such structures to the case of a neutron star gives the maximum mass and size of the star to be 2.31 solar masses and 12.2 km. (author)