Showing papers by "University of Córdoba (Spain) published in 1971"
TL;DR: In this paper, a general method of solving Einstein's equations is presented in the usual description, i.e., in terms of the scale factorT(t), and its general application to models containing interacting radiation and matter is explicitly given.
Abstract: Cosmological models with pressure are considered. A general method of solving Einstein's equations is presented in the usual description, i.e., in terms of the scale factorT(t). Its general application to models containing interacting radiation and matter is explicitly given. A particular class of models is studied which are ‘radiation-like’ in their early history and ‘matter-like’ at present. Their analytic solutions are given for all three values of the space curvature constant.
19 citations
01 Jan 1971
TL;DR: In this article, the problem arose that in the Clouds no variables were known with a period shorter than one day, therefore Cordoba Observatory began a search for stars fainter than had been studied up to then at Harvard Observatory.
Abstract: About twenty years ago the problem arose that in the Clouds no variables were known with a period shorter than one day, therefore Cordoba Observatory began a search for stars fainter than had been studied up to then at Harvard Observatory. Blinking 28 pairs of plates an enormous number of variables was found and among them a significative number with periods between O.d 2 and 1.d 5, whose magnitudes were between 17th and 18th. At the meeting of the Galaxies Commission in Rome in 1952 I announced this discovery and at the same time Thackeray reported to have found variables of the RR Lyrae type but with a magnitude of 19. Since then the location of both groups and their belonging to the Clouds has been discussed.