On the Complex Light Variations of α 1 Herculis: One of the Nearest AGB Red Giants

Authors:
Open Access
Publisher website
Google Scholar
Abstract
α 1 Her is a ∼3rd-mag semi-regular/irregular, luminous M5 Ib-II red giant and one of the nearest asymptotic giant branch (AGB) stars. It is the brightest member of a triple-star system, fortuitously permitting well-constrained age and fundamental properties. We investigate the star’s pulsation and convection-driven light variations utilizing ∼80 yr of visual measures and over a decade of photoelectric/CCD V -band observations from the American Association of Variable Star Observers (AAVSO) database. Period analyses were conducted using Weighted Wavelet Z-transform (WWZ) and CLEANest programs from the Peranso-3 period-analysis software. Analysis of the visual data reveals low-amplitude (∼0.2–0.4 mag) cycles of ∼1360 day, and ∼9–10 yr, along with an apparent long-term brightness increase of ∼0.2 mag. Investigations of over ∼13 yr of V -band observations find complex periodicities of ∼123, ∼200, and ∼390–490 day, along with a ∼9–10 yr oscillation.