Researchers from the University of Missouri, including R Ignace, C Erba, K DeGennaro, and G Henson, have recently published a study that delves into the complexities of polarimetric observations of evolved late-type stars. Their work, titled “Modeling of Rayleigh Scattering and Interstellar Polarization for Evolved Late-Type Stars,” offers insights that could have practical applications in the energy sector, particularly in the development of advanced solar technologies.
Evolved late-type stars, such as Mira-type or semi-regular variable objects, often exhibit variations in brightness and spectral features. These stars can also show polarimetric variability, indicating that their light is not symmetrically distributed. This asymmetry can be caused by various factors, including the presence of a binary companion, variations in the stellar atmosphere, or aspherical circumstellar envelopes. The study focuses on two primary sources of polarization in these stars: Rayleigh scattering and dust scattering.
Rayleigh scattering, which is responsible for the blue color of the sky, has a classic wavelength dependence of lambda^-4. However, this signature can be obscured by interstellar polarization (ISP). The researchers explored strategies for interpreting polarimetric observations when ISP cannot be removed. They introduced a “hybrid” spectrum that combines both Rayleigh polarization for the stellar contribution and the Serkowski Law for the interstellar contribution. Their findings indicate that the polarization spectral slope can be more shallow than expected from Rayleigh scattering alone.
For stellar variability, the study found that shorter wavelengths exhibit higher amplitude changes when Rayleigh scattering dominates the interstellar signal. Additionally, anomalous slopes can occur over limited wavelength intervals if the stellar and interstellar position angles differ by 90 degrees. These results have implications for photopolarimetry methods and were applied to the study of variable polarization from the carbon star, R Scl.
The practical applications of this research for the energy sector lie in the development of advanced solar technologies. Understanding the polarization of light from stars can help improve the efficiency of solar panels and other solar energy technologies. By better interpreting polarimetric observations, researchers can gain insights into the behavior of light, which can be harnessed more effectively for energy production.
This research was published in the journal Monthly Notices of the Royal Astronomical Society.
This article is based on research available at arXiv.