AAS Meeting #193 - Austin, Texas, January 1999
Session 46. Photometric Observations of Variable Stars
Display, Thursday, January 7, 1999, 9:20am-6:30pm, Exhibits Hall 1

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[46.13] Trend Analysis of Long Period Variables

J. A. Mattei, G. Foster (AAVSO)

We have performed a trend analysis of 383 Oxygen-rich and Carbon-rich long period variables (LPVs) using 90 years of AAVSO data, as a continuation of our study of the long-term behavior of LPVs (Mattei & Foster 1997, BAAS vol. 29, no. 5, 46.08). We studied the period and amplitude, as well as the mean magnitude and asymmetry (time from minimum to the following maximum as a fraction of the period). Our analysis indicates that the period is a much more stable parameter than the others; longer-period stars are more likely to show period fluctuations than shorter-period stars. The light curve asymmetry is the parameter most likely to show a trend; 50% of the sample stars show some trend in their asymmetry. A significant fraction of the stars seem to be getting fainter in their mean visual magnitude, while a very small number appear to be brightening. Also, the Carbon-rich LPVs show significant differences in their light curve behavior from the Oxygen-rich LPVs. We point out a few stars that show extreme time evolution of their light curve parameters, many of which deserve detailed study.

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The author(s) of this abstract have provided an email address for comments about the abstract: aavso@aavso.org

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