A new DDO calibration of effective temperature for evolved late-type stars

Abstract

The DDO Co(45-48)/Co(42-45) diagram for luminosity classes I, III, and V stars is redefined and the ability of the DDO system to assign MK spectral types is examined. Using the scale of Bell and Gustafsson (1989, MNRAS 236, 653) as reference, a new DDO calibration of effective temperature is presented. It is shown that the original Osborn's scale underestimates the temperature in about 170 K. This paper will be published in detail elsewhere.