SIMBAD references

TW Dra is a well-known short-period Algol-type system. It belongs to the class of oEA stars (Algol-type systems with a δ Scuti-like oscillating primary component). We investigate the TW Dra system based on high-resolution spectra taken in 2007 and in 2008 to derive precise stellar and system parameters and to check for phases of active mass transfer. We derived a precise orbital solution and the extracted spectra of the stellar components of the TW Dra system. The analysis of the spectrum of the primary shows that it is a normal A5-type star with a chemical composition close to solar. By means of the Shellspec07_ inverse program we calculated precise stellar and system parameters from the composite spectra. All results agree with those from the most recent photometric study. During both epochs of observations, the system can be well modeled without counting for mass transfer effects, assuming a spherical configuration of the primary and a Roche-lobe filling secondary. Thus, we conclude that the star was in quiet phases during both epochs of observations.