Microlensing of radially pulsating stars

Abstract

ABSTRACT In this paper, we study the microlensing of radially pulsating stars. It is possible to discern and characterize the properties of distant, faint pulsating stars using high-cadence microlensing observations. By combining the stellar variability period with microlensing, we can obtain the source distance, type and radius, and we can better determine the lens parameters. Considering the variations in the radius and surface temperature of radially pulsating stars periodically, their microlensing light curves can be obtained by multiplying the magnification factor with a variable finite size effect by the intrinsic brightness curves of the pulsing source. The variable finite size of the source due to pulsation can be significant for transit and single microlensing with caustic-crossing features. This type of deviation in the magnification factor is considerable when the ratio of the source radius to the projected lens–source distance is in the range of ρ⋆/u ∈ [0.4, 10] and when its duration is short and of the same order as the time of crossing the source radius. Other deviations due to variable source intensity and its area make coloured and periodic deviations, which are asymmetric with respect to the signs of the pulsation phase. The positive phase makes deviations with larger amplitude than the negative phase. These deviations dominate in filters with short wavelengths (e.g. the B band). The position of the magnification peaks in the microlensing of variable stars varies and this displacement differs in different filters.