Measuring the orbital inclination of Z Andromedae from Rayleigh scattering
Authors:
A. Skopal, N. Shagatova
Image & caption:
Please click on image thumbnail to get more info:
Image caption::
Left top: The UV spectrum of Z And. The continuum around the Ly-alpha line is attenuated by the Rayleigh scattering on neutral atoms of H with the column density n(H) = 3.9 x 10E+22 cm-2. Bottom panel shows theoretical n(H) as a function of the orbital inclination i. Their intersections with the observed value correspond to i ~ 60 degrees. A high value of i is supported by the orbital variation of the far-UV continuum and the OI]1641 line (right panels).
Description:
Symbiotic binaries consist of a cool giant and a very hot white dwarf (WD). The giant supplies a large amount of neutral hydrogen-rich material into the binary environment. The high-energetic radiation from the WD ionizes this material so that its neutral remainder has the shape of a conus with the giant at its top. If the WD's photons come through this region, they will be attenuated by the Rayleigh scattering process on the neutral atoms of hydrogen. This effect is observable only in the case, when the relatively narrow neutral region is located between the WD and the observer. In this paper we elaborated a model of the light attenuation by the Rayleigh scattering as a function of the orbital inclination and the phase. Comparing the calculated hydrogen column densities with that derived from observations, we determined the orbital inclination of Z And to 59+3/-2 degrees. Such the high inclination is supported independently by the variation of the far-UV continuum and attenuation of the OI]1641 line around the inferior giant conjunction. The orbital inclination represents crucial parameter for a correct interpretation of the collimated jets, we discovered in 2006 (see VS-2009).
Reference:
Astronomy & Astrophysics, 547, article no. A45, p. 1-6 (2012)
SK
SAS
