The Solar Apex

Abstract

MR. O. R. WALKEY has examined the literature on the position of the solar apex (Mon. Not. Roy. Astro, Soc, 106, No. 4; 1946). Table 1 shows the marked divergences in the positions determined from 1933 to 1941. Mr. Walkey uses as his basis Moore's "Catalogue of Radial Velocities"(Pub. Lick Obs., 18; 1932) and Boss' "General Catalogue"(Carnegie Pub., No. 468; 1937). It is suggested that the divergences just referred to may be partly due to rotation in a probable local cluster which leavens the allowance made for galactic rotation-a view to which some support is given by the increased declination in the apex with increased magnitude of the stars used. Mr. Walkey believes that our ignorance of the actual peculiar motions of the stars, and the consequent assumptions required to fill this gap in our knowledge, may undermine "the refined mathematical edifice built thereon". Using the two catalogues mentioned, he considers the sense alone of their respective motions, whether reflecting "pro"-solar motion, or the reverse-"con". In this way he by-passes assumptions for distance (for cross-motions), etc., and also the general assignment of arbitrary limits for acceptable motions. A full explanation of the method appears in the paper, to which reference must be made for details of the method ; Mr. Walkey states that the method is a development of that mentioned by Russell, Dugan and Stewart in "Astronomy", vol. 2. As a result of his investigation, involving 40,720 star motions, Walkey's conclusions are as follow : position of solar apex, 1900·0 ; R.A. 270·2° ± 0·°, Dec. + 28·7 ± 0·5°. The solar velocity of approach was found to be 20·5 ± 0·6 km./sec, its galactic planar component being 19·0 km,/sec. and the normal 7·75 km./sec.