THE ASTRONOMICAL JOURNAL    VOLUME 112, NUMBER 2, PAGE 491          AUGUST 1996

            LATE-TYPE STARS IN M31. II. C-, S-, AND M-STAR SPECTRA

                                JAMES P. BREWER

       European Southern Observatory, Casilla 19001, Santiago 19, Chile
                       Electronic mail: jbrewer@eso.org

                               HARVEY B. RICHER

    Department of Geophysics and Astronomy, University of British Columbia,
             129-2219 Main Mall, Vancouver, B.C., V6T 1Z4, Canada
                     Electronic mail: richer@astro.ubc.ca

                              DENNIS R. CRABTREE

    Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics,
National Research Council, 5071 W. Saanich Road, Victoria, B.C. V8X 4M6, Canada
                     Electronic mail: crabtree@dao.nrc.ca


                                   ABSTRACT

    We present spectra of AGB stars in M31 for which observations had been
    previously secured using a four-band photometric system (FBPS).  The
    FBPS had been used to identify M-, S-, and carbon-star (C-star)
    candidates, and we use the spectra to show that the FBPS did an
    excellent job at identifying C- and M-stars.  Of the 48 C-stars for
    which spectra were obtained, 7 have strongly enhanced 13C bands
    (J-stars), 2 have strong Halpha emission, while 3 are found to exhibit
    enhanced Li absorption (Li-stars).  Both the J- and Li-stars are
    fainter than predicted by current theoretical models, while the colors
    of the Halpha stars suggest they may be in the terminal phases of their
    evolution.  The C2 and CN bandstrengths of the C-stars are measured,
    and no correlation between these bandstrengths and either Mbol or (V-I)
    is found.  It is suggested that this lack of correlation is due to an
    age spread.  The spectra of the first confirmed S-star in M31 is
    presented, and two evolutionary pathways are suggested to account for
    this star's high luminosity.