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.
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Acknowledgements
This research was supported by the program of Presidium of RAS-21, the program of the Department of Physical Sciences of RAS-16, by the Federal Target program “Scientific and scientific-pedagogical personnel of innovative Russia” 2009–2013 and the Grant from President of the Russian Federation “The basic Scientific Schools” NSh-1625.2012.2. Authors are very grateful to anonymous referee for very useful remarks.
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Silant’ev, N.A., Alekseeva, G.A. & Novikov, V.V. Influence of temperature fluctuations on continuum spectra of cosmic objects. Astrophys Space Sci 342, 433–442 (2012). https://doi.org/10.1007/s10509-012-1190-7
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DOI: https://doi.org/10.1007/s10509-012-1190-7