A description is given of two new systems of stellar classification, which are applicable only to stars of early spectral type (O-G0).Each star is characterized by two or three well-defined parameters (the same parameters are used for all stars), and it is the numerical value of these parameters which enables stars to be differentiated.The first two parameters, which measure the size and position of the Balmer discontinuity, enable a classification to be established which is equivalent to that of Morgan, Keenan, and Kellman, but is capable of greater precision. The introduction of a third parameter, the absolute gradient in the photographic region, makes it possible to classify stars which could otherwise not be included in previous classifications (metallic-line A-type stars, population II, etc.).
- 1 - natural sciences ; 2 - physics & astronomy ; 3 - astronomy & astrophysics
- 1 - sciences appliquees, technologies et medecines ; 2 - sciences exactes et technologie ; 3 - terre, ocean, espace ; 4 - geophysique externe