Low energy observations of Cygnus X-2 by Ariel VI

Abstract Ariel VI observations of Cygnus X-2 have revealed a rather flat spectrum between 0.1 and 1.5 keV with variable emission at low energy. Of the two conflicting interpretations of this object in terms of i) a distant high-luminosity (L x ∼ 10 38 ergs s −1 ) binary and ii) a nearby low-luminosity (L x ∼ 10 35 ergs s −1 ) degenerate dwarf system, our measurements support the latter.