Correlation of Spectroscopic and Photometric Data

Abstract

AbstractThis paper reviews first of all the various problems connected with the establishment of a relationship between MK type and various photometric parameters: reddening, binarity, rotation. Mention is then briefly made of the various relationships proposed in the literature for the UBV, uvbyβ, DDO, Vilnius and Geneva systems. The MK classification is a bidimensional classification which provides also indication of peculiarity (Ap, Am, Ba stars, for example). The problems arising from stars having a peculiar chemical composition are examined. The establishment of a relationship between a color index and the MK type or the location of the various MK types in a photometric diagram are both classical methods to obtain a correlation between a photometric system and the MK schema. However a new solution is proposed by the method of stellar boxes, which allows us to find all the stars having the same colors. If many photometric systems are limited in their possibilities of classifying all stars from O to M, the GENVIL (or VILGEN) system, formed with four filters of the Geneva system and three of the Vilnius system and at present under consideration, will certainly provide a very good means to this end. Finally, the new spectroscopic and photometric catalogues available at the Stellar Data Center in machine-readable form offer us the possibility of improving the present correlations.