2012A&A...547A..45S

The orbital inclination of the symbiotic prototype Z And has not been established yet. At present, two very different values are considered, i∼44° and i>73°. The correct value of i is a key parameter in, for example, modeling the highly-collimated jets of Z And. To measure the orbital inclination of Z And. First, we derive the hydrogen column density (n_H), which causes the Rayleigh scattering of the far-UV spectrum at the orbital phase φ=0.961±0.018. Second, we calculate n_H as a function of i and φ for the ionization structure during the quiescent phase. Third, we compare the n_H(i,φ) models with the observed value. The most probable shaping of the HI/HII boundaries and the uncertainties in the orbital phase limit i of Z And to 59°-2°/+3°. Systematic errors given by using different wind velocity laws can increase i up to ∼74°. A high value of i is supported independently by the orbitally related variation in the far-UV continuum and the obscuration of the OI]λ1641Å emission line around the inferior conjunction of the giant. The derived value of the inclination of the Z And orbital plane allows treating satellite components of Hα and Hβ emission lines as highly-collimated jets.