Contributed Talk - Splinter TimeDomain

Wednesday, 15 September 2021, 17:36   (virtual TimeD)

Multiwavelength study of Miras variability

Patryk Iwanek
Astronomical Observatory, University of Warsaw

Pulsating stars have been known for over 400 years (since the discovery of periodic variability of o Ceti made by David Fabricius in 1596), yet their nature still leaves many unanswered questions. Thanks to both the rapidly evolving domain of observational astronomy and the great technological progress over past decades, it is nowadays possible to observe the sky at a wide range of wavelengths. Such a synoptic approach allows studies and in-depth analyses of the nature of stars at every evolutionary stage. We comprehensively study the variability of Miras in the Large Magellanic Cloud (LMC) by simultaneously analysing light curves in 14 bands in the range of 0.5 to 24 microns. We model densely covered, 20-years-long I-band light curves for over 1600 Miras, collected by The Optical Gravitational Lensing Experiment (OGLE). We fit these models to other optical/near-infrared/mid-infrared data collected by surveys that include VMC, WISE, and Spitzer to derive the variability amplitude ratio and phase-lag between bands as a function of wavelength. We show that the variability amplitude ratio declines with increasing wavelength, while the phase-lag between bands increases slightly with increasing wavelength. We analyze spectral energy distributions (SEDs) for 140 Miras, and based on synthetic light curves we provide Period-Luminosity Relations (PLRs) in 42 bands from existing and future sky surveys.