Astronomy and Astrophysics – Astrophysics
Scientific paper
Feb 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004a%26a...415..273l&link_type=abstract
Astronomy and Astrophysics, v.415, p.273-282 (2004)
Astronomy and Astrophysics
Astrophysics
10
Stars: Binaries: Symbiotic, Stars: Winds, Outflows, Stars: Individual: Ag Dra
Scientific paper
The halo symbiotic star AG Dra has been monitored spectroscopically at the Tartu Observatory, Estonia, from September 1997 to March 2003. Altogether 189 spectra are used in the present paper. In addition, photometric UBVri observations at the Piwnice Observatory, Poland, from March 1996 to May 2003 are presented. Equivalent widths (EW) of the strongest emission lines (Hα, Hβ, He II λ 4686, O VI Raman scattered ⪉mbda 6825) appear to be strongly variable, and in general, correlate with the U brightness of the star. No apparent correlation with the orbital motion of the binary system was found, except for Hβ in the quiescent state. At the same time, there is a clear convergence of the high values of EW to certain phases according to the shorter photometric period (378.5 days) proposed by Bastian (1998) and the pulsational period of the cool giant (355.27 days) by Gális et al. (1999). Higher resolution spectra show variability of the Hα profiles, with weak absorption component on the blue wing of the line around photometric minimum if the star is in quiescent state. The significant role of the cool giant in the activity of AG Dra is discussed.
Based on observations collected at Tartu Observatory, Estonia and Piwnice Observatory, Toruń, Poland
Tables 2-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/415/273
Annuk Kalju
Burmeister Mari
Gałan C.
Leedjarv Laurits
Mikołajewski Maciej
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