Giantic Roundchroms of Binary Systems SX Cas and 22 Vul

The IUE observations do not favor the chromospheric origin of typical chromospheric emission lines, of the doublet 2800 MgII first of all, in close binary systems SX Cas and 22 Vul, both with a cool giant-supergiant as primary, and a hot B7–B8 star as secondary. Here, it is shown that the concept of common chromospheres – roundchroms can explain the unusual fluxes of chromospheric emission lines in these systems. The hot components of these binaries – B type stars, themselves are assumed to represent local binary systems with a white dwarf and an accretion disc: the latter being the source of generation of transition zone type high excitation emission lines 1240 NV, 1400 SiIV, 1550 CIV, etc. It is concluded, that roundchroms of giant sizes, of order of 100 R⊙ and larger, are not rare events for the RS CVn type binary systems. This revised version was published online in July 2006 with corrections to the Cover Date.