This paper is based on a statistical study of observations over an exceptionaly long period of time. We confirm previously known results that can help explain many other observational data and constrain the models.
Our main result is to produce a classification of LPVs from relatively easily observable parameters of their light curves that can be used jointly with IRAS colors to distinguish carbon- from oxygen-rich stars. One of its strengths is that all parts of these stars (stellar and circumstellar media, extended envelope, and their couplings) are taken into account.
Acknowledgements
We express our thanks and appreciation to variable star observers around the world whose observations over decades have make this work possible. J.A. Mattei acknowledges gratefully NASA grant NA6W-1493, which partially supported this work. We thank C. Mercier for his help in making the figures, the staff of INRIA for authorizing use of SICLA to do the classification, and G. Foster for assistance in preparing the manuscript.