Orbits for two short-period and two long-period binaries

In this paper, new orbital elements and the quantities following from them for four binaries are analysed. For three of them, WDS 04340 + 1510 = CHR 17, WDS 06290 + 2013 = BTZ 1Aa and WDS 19535 + 2405 = DIU 4, the orbits have been calculated before and here improved orbital elements are presented. The reason is that recent measurements show higher residuals with respect to the corresponding ephemerides calculated by using the earlier orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. As for the fourth binary, WDS 07106 + 1543 = J 703, this is the first orbit obtained for it. Out of these four binaries two have short periods and small separations so that it has been possible to resolve them by using interferometric measurements only; the other two have large periods. The ephemerides are presented for all the four stars, whereas the total masses and mass estimates for the components, determined by using trigonometric parallaxes and spectral types, are presented for three of them only (J 703 is exception). (C) 2008 Elsevier B.V. All rights reserved.