Mira Data in the AAVSO International Database (Abstract)

Volume 33 number 1 (2005)

Matthew Templeton

Abstract

(Abstract only) The AAVSO International Database contains observations of several thousand variable stars, with light curves spanning over a century for some objects. Among these are many Mira variables, one of the most popular types of variable star in the AAVSO observing program. Over 1,500 Miras are officially in our program, and several hundred of these are well-observed. As a result of the AAVSO Validation Project, most of these data are validated and available from our website by the astronomical community. The AAVSO International Database continues to grow on a daily basis. Our observer community also continues to grow, as do the number of stars observed and the sophistication and power of the equipment available to our observers. Many of our observers can now perform calibrated, multiwavelength photometry, and the AAVSO has begun a pilot program to distribute near-infrared photometers to our observers, adding J- and H-band photometry to our menu of available data for some stars. Our ability to study the Mira variables will only improve as light curves grow longer and increase in photometric precision, depth, and spectral coverage. Long-term light curves have many applications in the study of Mira variables, from the refinement of periods and detection of multiperiodicity, to the measurement of real-time evolution. Because they lie on the asymptotic giant branch, Mira stars are believed to occasionally undergo significant evolutionary events such as thermal pulses on timescales of hundreds or thousands of years. Light curves that span several decades to over a century now enable us to detect and measure these events. We have observed large, long-term period changes in a small percentage of stars in the AAVSO International Database. Some of these changes are likely due to thermal pulses, and we speculate on other possible causes of this interesting behavior.