Variability Properties of Red Giants and Supergiants in the AAVSO Binocular Observing Program
Volume 51 number 2 (2023)
- John R. Percy
- Department of Astronomy and Astrophysics, and Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada; john.percy@utoronto.ca
- Sandra Zhitkova
- Department of Astronomy and Astrophysics, and Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
Abstract
The AAVSO Binocular Observing Program contains 153 stars, almost all of them red giants (127) or red supergiants (10). In this paper, we use Fourier and light curve analysis of visual and photoelectric observations in the AAVSO International Database to determine periods and amplitudes of these stars. Of the stars analyzed, 110 stars had sufficient data and periodicity to yield results. The stars pulsate in the fundamental and/or first overtone (at least 24 are bimodal); more luminous stars tend to pulsate in the fundamental. In addition, at least 61 of the stars had a “long secondary period” (LSP) 5 to 10 times the pulsation period. We determine and discuss the pulsation and LSP amplitudes. These are known to be variable with time. The variability properties of our stars are determined, to some extent, by the way in which the program stars were originally selected. The results are also affected by the limitations of the data, including limited accuracy of the visual data, seasonal and other gaps in the data, and the complexity of the stars' variability, including time-variable periods and amplitudes.