Influence of temperature fluctuations on continuum spectra of cosmic objects

TL;DR

This paper examines how small temperature fluctuations in cosmic objects' atmospheres affect their continuum spectra, providing a method to incorporate these effects into spectral models and analyzing their impact on observed spectra and color indices.

Contribution

It introduces a procedure to account for temperature fluctuations in continuum spectra calculations, extending traditional models that ignore such fluctuations.

Findings

Temperature fluctuations can significantly alter the continuum spectra in Wien's region.

The additional spectral component depends on derivatives of the observed spectrum and fluctuation degree.

Temperature-dependent absorption factors are crucial for accurate spectral corrections.

Abstract

The presence of convective and turbulent motions, and the evolution of magnetic fields give rise to existence of temperature fluctuations in stellar atmospheres, active galactic nuclei and other cosmic objects. We observe the time and surface averaged radiation fluxes from these objects. These fluxes depend on both the mean temperature and averaged temperature fluctuations. The usual photosphere models do not take into account the temperature fluctuations and use only the distribution of the mean temperature into surface layers of stars. We investigate how the temperature fluctuations change the spectra in continuum assuming that the degree of fluctuations (the ratio of mean temperature fluctuation to the mean temperature) is small. We suggest the procedure of calculation of continuum spectra, which takes into account the temperature fluctuations. As a first step one uses the usual model of a photosphere without fluctuations. The observed spectrum is presented as a part depending on mean temperature and the additional part proportional to quadratic value of fluctuation degree. It is shown that for some forms of absorption factor the additional part in Wien's region of spectrum can be evaluated directly from observed spectrum. This part depends on the first and second wavelength derivatives, which can be calculated numerically from the observed spectrum. Our estimates show that the temperature dependence of absorption factors is very important by calculation of continuum spectra corrections. As the examples we present the estimates for a few stars from Pulkovo spectrophotometric catalog and for the Sun. The influence of temperature fluctuations on color indices of observed cosmic objects is also investigated.