A multiwavelength study of spectral variations in the CX Draconis binary

An extensive collection of spectroscopic observations of the interacting bi nary CX Dra spanning a 23 year interval have been analyzed. This study incl udes a refinement of the orbital solution of CX Dra; equivalent width measu rements that show short-, medium-, and long-term behavior of the difference profiles; a calculation of the Balmer decrement; velocity maps based on th e velocity curves of the Ha and He I difference emission peaks; trailed spe ctrograms of the H alpha, H beta, He I, and Si n Lines; and Doppler tomogra ms at these four wavelengths. The main conclusions are: 1. The circumstellar environment in the system changes in cycles of hundred s of days. The length of the cycles is variable. These cycles may be part o f a "super" 4000 day cycle. 2. The equivalent widths of the difference H alpha and He I lambda 6678 lin es are modulated with the orbital period of 6.696 days. The corresponding p hase diagrams indicate a great deal of scatter, but the modulation is quite conspicuous when long data strings are used. The pattern of the phase diag ram suggests a permanent presence of the emission in H alpha, He I lambda 6 678, and Si II lambda 6371 lines. 3. The radial velocities of the H alpha emission peak follow an S-wave. The resulting velocity map shows that the source of the single-peaked emission lies close to the L1 point, roughly between the primary and L1 point. 4. Doppler tomograms constructed for H alpha observed and difference profil es show that the emission comes from a region of low velocity, a gas stream , and an accretion disk. The H beta emission arises from a region that is c ospatial with the H alpha source. The Doppler tomograms for He I lambda 667 8 and Si n lambda 6371 lines suggest that emission in this gas also origina tes from a locus of a disk around the primary star. 5. The model based on the equivalent widths of the difference pro files, th e trailed spectrograms, and Doppler tomograms of the H alpha, He I lambda 6 678, Si II lambda 6371, and H beta lines suggests that the main source of t he Ha emission is about halfway between the stars at a distance of 0.49a fr om the primary star, and that the He I and Si n emission sources arise from an accretion disk centered on the primary star.