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Session 96 - Cepheids and Supergiant Variable Stars.
Display session, Thursday, January 16
The calibration of a photometric system used to detect spectral type changes of M-type stars is described. The system consists of three filters used to measure an index of TiO band strength, a color index, and an infrared continuum magnitude as described by Wing (1992, J.AAVSO, 21, 47). A plot of TiO index versus spectral type shows the system to be sensitive to spectral changes of approximately 1/2 subtype over the range of M1 to M7. The system will be used to provide coarse spectral information to supplement the infrared and visual light curves of M-type variables. We have established absolute magnitudes in all three filters for a set of 10 standard stars and have begun synoptic observations of Mira variable stars. Light curves with corresponding spectral type and color changes will be presented for six Mira stars: Z Oph, T Her, W Lyr, RT Cyg, CN Cyg, and R Vul.
Program listing for Thursday