Methods of parametrization. Interstellar Extinction

Study of the interstellar extinction in the Galaxy. Development of parametrization methods for the stars.

• We study possibilities to parameterize stars and interstellar medium from multicolor photometry performed in modern photometric surveys (GALEX, SDSS, 2MASS, WBVR, etc.). For this purpose, we have developed a method to estimate stellar radius from effective temperature and gravity with the help of evolutionary tracks and model stellar atmospheres. In accordance with the evolution rate at every point of the evolutionary track, star formation rate, and initial mass function, a weight is assigned to the resulting value of radius that allows us to estimate the radius more accurately.
• Detection of a composite flux in photometry can also serve as an indication of a photometrically unresolved binarity and can contribute to the parameterization of the components of binary systems. We have developed a method of automatic photometric detection of binaries, based on multi-color photometry, theoretical stellar spectral energy distributions and general understanding of binary evolution. When one considers an ultraviolet photometry, then, in combination with optical and infrared photometry, interstellar reddening can be easier distinguished from temperature reddening. Usage of an interstellar extinction law gives us theoretical color-indices of reddened objects, both single stars and unresolved binaries. When plotted on a multidimensional color space, they allow us to indicate areas, where unresolved binaries can be easily separated from single stars, and to identify binaries among objects, cross-matched in photometric surveys.

  Investigators:
  O.Yu. Malkov, S.G. Sichevskij, E.Yu. Kilpio, D.A. Chulkov, in collaboration with A.V. Mironov (Sternberg Astronomical Institute of the Moscow State University).

  Main publications:

• Malkov O.Yu., Mironov A.V., Sichevskij S.G., “Single-binary star separation by ultraviolet color index diagrams”, 2011, Astrophys. Space Science 335, 105-111.
• Sichevskij S.G., Mironov A.V., Malkov O.Yu., “Classification of stars with WBVR photometry”, 2013, Astronomische Nachrichten 334, 832-834.
• Chulkov D.A., Prokhorov M.E., Malkov O.Yu., Sichevskij S.G., Krusanova N.L., Mironov A.V., Zakharov A.I., Kniazev A.Yu., “Detection of unresolved binaries with multicolor photometry”, 2015, Baltic Astronomy 24, 137-143.