Observations (dots) and models (lines) presented in Sect.3.2. a) N-band flux spectra; b) Visibilities, observations affected by telluric absorption are omitted; c) SEDs, with observations taken from de Wit et al. (2009) compilation. Graph styles are the same for each panel: 1) green dash-dotted line – ZAMS star  +  envelope; 2) red dashed line – cool hypergiant  +  envelope; 3) blue full line – ZAMS star  +  envelope and a gaseous disk. Panel c) shows the spectrum of the accretion disk (blue dotted line) and the observed ISO-SWS spectrum (full black line). Models that fit the SED only (Sect. 3.1) are not shown here.