Do we have a radio powerful star without a chromosphere?

Abstract

Two radio stars are selected, both equally powerful in microwave radio emission, but one of which, HD 101379, with a superpower chromosphere, and the other one, HD 132742, without a noticable chromosphere. On IUE recordings of HD 132742, a binary system like HD 101319, the doublet 2800 Mg II appears in absorption (Figure 1a). However, in the last case the faint emission traces of k and h Mg II have been discovered in the lowest parts of absorption profiles. The reconstructed profiles of these emission details seem to be shifted to the relation of absorption profiles, which may be interpreted as a confirmation of the non-chromospheric nature of these details. In the case of radio star HD 101379, also a binary system,on the contrary, the doublet 2800 Mg II appears as a strong emission, without shift. These limiting cases may be combined assuming that the sources of both types of emission, radio and magnesium doublet are located in the space between the components of binary systems. The parameters of these sources are obtained.