Measuring the orbital inclination of Z Andromedae from Rayleigh scattering

作者：Skopal A^*; Shagatova N

来源：Astronomy & Astrophysics, 2012, 547: A45.

DOI：10.1051/0004-6361/201117393

• binaries: symbiotic
• scattering
• stars: individual: Z And

Context. The orbital inclination of the symbiotic prototype Z And has not been established yet. At present, two very different values are considered, i similar to 44 degrees and i greater than or similar to 73 degrees. The correct value of i is a key parameter in, for example, modeling the highly-collimated jets of Z And.
Aims. To measure the orbital inclination of Z And.
Methods. First, we derive the hydrogen column density (n(H)), which causes the Rayleigh scattering of the far-UV spectrum at the orbital phase phi = 0.961 +/- 0.018. Second, we calculate n(H) as a function of i and phi for the ionization structure during the quiescent phase. Third, we compare the n(H)(i, phi) models with the observed value.
Results. The most probable shaping of the HI/HII boundaries and the uncertainties in the orbital phase limit i of Z And to 59 degrees - 2 degrees/+3 degrees. Systematic errors given by using different wind velocity laws can increase i up to similar to 74 degrees. A high value of i is supported independently by the orbitally related variation in the far-UV continuum and the obscuration of the OI]lambda 1641 angstrom emission line around the inferior conjunction of the giant.
Conclusions. The derived value of the inclination of the Z And orbital plane allows treating satellite components of H alpha and H beta emission lines as highly-collimated jets.

• 出版日期2012-11