GRAVITATIONAL REDSHIFTS AND ANGULAR DIAMETERS OF COLLAPSED OBJECTS

Light propagation from the surfaces and the interiors of static, spherically symmetric collapsed objects with isothermal cores and adiabatically stable envelopes capable of giving high internal gravitational redshifts is studied within the framework of general relativity. Optical appearance and variation of angular diameter are discussed in relation to the equation of state. A method to estimate the mass and the distance of the object from the angular diameter or the period of flux variation has been outlined and illustrated with the example of the QSO 3C 9. © 1975 Royal Astronomical Society.