INFRARED VELOCITIES OF LONG-PERIOD VARIABLES - CO DELTA-NU=3 W 4 MIRAS AND 5 SR VARIABLES

Time series of high resolution spectra have been obtained for a set of 9 long period variables (LPVs), 4 Miras, and 5 semiregular variables (SRVs) in the 1.6-1.8 mu m infrared. The vibration-rotational lines of CO Delta v = 3 in this spectral interval have previously been shown t o be good probes of the pulsational properties of cool variable stars. We use these spectral lines to show the differences and similarities in the radial velocity amplitude and excitation temperature among the Mira, SRa-, and SRb-type variables. All Miras of our sample show simil ar radial velocity variations and similar amplitudes independent of th eir period. The SrVs differ from the Miras by significantly lower ampl itudes. All the LPVs show random velocity changes at the few km s(-1) level. We iind a correlation between radial velocity amplitude and vis ual amplitude. (C) 1997 The American Astronomical Society. [S0004-6256 (97)04012-0].