科研之友
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摘要
The IUE ultraviolet spectrum for a supergiant of type G Ia, HD 135345, was obtained for the wavelength region 2000-3000 angstrom. In this spectrum, the continuum as well as the feature of the Mg II doublet at 2800 angstrom is anomalous. The observed level of continuum increases toward short wavelengths to 2000 angstrom, verifying that this supergiant actually is a binary system with a hot companion. The anomalies in the magnesium doublet are the complete absence of chromospheric emission and the very small equivalent width of the doublet absorption: the equivalent width is 4 angstrom, which is 7.5 times smaller than that for a typical G5 star. This too can be explained in terms of the binary nature of this supergiant with a hot companion. The main parameters of this binary system have been obtained: the spectral classes are G5 Ib and B2 II, the effective temperatures T(G) = 5500 K and T(B) = 20,000 K, the ratio of radii R(G)/R(B) = 10.8, the radii R(G) = 125 R. and R(B) = 11.6 R., the visible magnitudes are V(G) = 5.45 and V(B) = 6.85.
- 出版日期1991-9-1
