Modified Gravity at Astrophysical Scales

Using a perturbative approach we solve stellar structure equations for low-density (solar-type) stars whose interior is described with a polytropic equation of state in scenarios involving a subset of modified gravity theories. Rather than focusing on particular theories, we consider a model-independent approach in which deviations from General Relativity are effectively described by a single parameter $\xi$. We find that for length scales below those set by stellar General Relativistic radii the modifications introduced by modified gravity can affect the computed values of masses and radii. As a consequence, the stellar luminosity is also affected. We discuss possible further implications for higher density stars and observability of the effects before described.Comment: 12 pages, 7figures, matches published versio

BARÓN D´HOLBACH: Sistema de la naturaleza.

Sin resume

Book Reviews

El Conflicto Honduras-El Salvador y El Orden Juridico Internacional -- On July 14, 1969, the armed forces of El Salvador invaded Honduras... This book provides an almost hourly account of the events preceding the conflict, the war plans executed before the conflict started, the initiation of Inter-American System machinery for settling disputes, the heated discussions among the representatives of the different nations of the OAS, and the consequences of the war itself. Also included is the necessary background on the political and economic conditions prevailing in both countries before the war and a thorough analysis of what role law and international legal machinery played--or might have played--at different stages of the conflict. Reviewed by Jorge L. Carro ============================= United States Foreign Relations Law: Documents and Sources, Vol. 1 (Executive Agreements). Michael J. Glennon and Thomas M. Franck Dobbs Ferry, New York: Oceania Publications, Inc., 1980. Pp. ix, 474. 40.00.-- This volume on United States executive agreements is the first of a multivolume series providing important documents and other materials dealing with the foreign relations power of the federal government and its constituent parts. Reviewed by David S.Clark =========================== Towards a New International Economic Order Mohammed Bedjaoui New York and London: Holmes & Meier Publishers,1979. Pp. 287. 16.50. When tracing the ideologies that animate and condition the current North-South debate over what has come to be called the New International Economic Order, MIT economist Jagdish Bhagwati identifies two dominant schools of thought regarding the existing international economic order. Reviewed by Burns H. Westo