Infrared observations and a model of β Lyr

The paper presents light curves of the eclipsing binary β Lyr at 1.2, 2.2, 3.6, 4.8 and 8.6 μ. The principal feature of these curves is that at long wavelengths the secondary minimum becomes deeper than the primary minimum. This can be explained by a plasma cloud around the secondary component of temperature 17 500 K and constant electron density of 1.4 x 1012cm-3 out to a distance 1.6 x 107 km. It is suggested that the secondary is a B4 or earlier type star. (author)