EDP Sciences
Free access
Volume 387, Number 1, May III 2002
Page(s) 139 - 150
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020335

A&A 387, 139-150 (2002)
DOI: 10.1051/0004-6361:20020335

The spectroscopic orbits and the geometrical configuration of the symbiotic binary AR Pavonis

C. Quiroga1, 2, J. Mikolajewska3, E. Brandi2, 4, O. Ferrer1, 2 and L. García2

1  Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET)
2  Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, La Plata, Argentina
3  Copernicus Astronomical Center, Warsaw, Poland
4  Comisión de Investigaciones Científicas de la Provincia de Buenos de Aires (CIC), Argentina

(Received 7 August 2001 / Accepted 30 January 2002 )

We analyze optical and near infrared spectra of intermediate and high resolution of the eclipsing symbiotic system AR Pavonis. We have obtained the radial velocity curves for the red and the hot component from the M-giant absorption lines and from the wings of H $\alpha$, H $\beta$ and He II  $\lambda$4686 emission profiles, respectively. From the orbital elements we have derived the masses, $M_{\rm g}=2.5~M_{\odot}$ and $M_{\rm h}=1.0~M_{\odot}$, for the red giant and the hot component, respectively. We also present and discuss radial velocity patterns in the blue cF absorption spectrum as well as various emission lines. In particular, we confirm that the blue absorption lines are associated with the hot component. The radial velocity curve of the blue absorption system, however, does not track the hot companion's orbital motion in a straightforward way, and its departures from an expected circular orbit are particularly strong when the hot component is active. We suggest that the cF-type absorption system is formed in material streaming from the giant presumably in a region where the stream encounters an accretion disk or an extended envelope around the hot component. The broad emission wings originate from the inner accretion disk or the envelope around the hot star. We also suggest that the central absorption in H profiles is formed in a neutral portion of the cool giant's wind which is strongly concentrated towards the orbital plane. The nebula in AR Pav seems to be bounded by significant amount of neutral material in the orbital plane. The forbidden emission lines are probably formed in low density ionized regions extended in polar directions and/or the wind-wind interaction zone.

Key words: stars: binaries: eclipsing -- stars: binaries: symbiotic -- stars: fundamental parameters -- stars: individual: AR Pav

Offprint request: C. Quiroga, claudioq@muchi.fcaglp.unlp.edu.ar

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