Astronomy and Astrophysics, volume 307, 516-528 (1996/3-2)
Extragalactic symbiotic systems. III. The stellar components of the systems in the Magellanic Clouds.
MUERSET U., SCHILD H. and VOGEL M.
Abstract (from CDS):
We present multifrequency data, ranging from ultraviolet and optical spectroscopy to infrared photometry, of the confirmed symbiotic systems in both Magellanic Clouds (SMC1, SMC2, SMC3, N60, Ln358, N73, S154, S147, LMC1, N67, and S63), as well as of Sanduleak's star, whose nature remains unclear. Because of the known distance, the Magellanic symbiotic systems enable us to derive the luminosity functions and other basic parameters of the binary components. We determine the spectral types, luminosities, and and temperatures of the cool components, and classify the objects in the s/d system which still seems applicable with the exception of Sanduleak's star. The most luminous red components are found in d-type symbiotics (L≃12000L☉) whereas those of s-types have luminosities below 6000L☉. Six objects (including the d-types) are of spectral type C, four of type K, and one of type M. The existence of s-types with a carbon star indicates that they either must be AGB stars or, if they are on the RGB, must have accreted carbon from their companion during its AGB evolution. In the HR diagram the symbiotic red components are located such that no deviations from single star evolution are recognizable. Also the separation between M and C stars occurs at the same location as for single stars. We also determine the luminosities, radii and temperatures of the hot components. They are found to have remarkably similar characteristics (L≃3000L☉, T≃130000K, and R≃0.1R☉). We propose that the hot components of the presently known symbiotic stars in the Magellanic Clouds mark the upper end of the luminosity function.
binaries: symbiotic - stars: carbon - stars: fundamental parameters - Hertzsprung-Russell diagram - stars: luminosity function - Magellanic Clouds
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