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The David Dunlap Observatory (DDO) Photometric System for Classification of Late-Type Stars

Published online by Cambridge University Press:  14 August 2015

R. D. McClure
R. D. McClure*
Affiliation:
Dept. of Astronomy, Yale University Observatory, U.S.A.

Abstract

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An intermediate bandpass filter system is described that is useful for classification of G and K stars in terms of effective temperature (spectral type), surface gravity (luminosity class), heavy element abundance, and interstellar reddening. The system measures the strength of the cyanogen band in the region shortward of λ4216, the break in the continuum at the G band, and a colour index in the λ4500–λ4900 region of the spectrum. The surface gravity parameter is independent of the cyanogen index, and the cyanogen band strength, after a surface gravity correction, is used as a measure of heavy element abundance.

Application of the system to the determination of the atmospheric parameters of open cluster giants, as well as of field stars, is discussed. The system has been used to isolate stellar populations among field stars without any prior knowledge of their distances. From observations on this system, the only open cluster found so far to have giants with stronger cyanogen band absorption than the Hyades giants is the intermediate age southern cluster NGC 2477.

Type
Part III: Photometric Classification
Information
Symposium - International Astronomical Union , Volume 50: Spectral Classification and Multicolour Photometry , 1973 , pp. 162 - 175
Copyright
Copyright © Reidel 1973 

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