Multiwavelength observations of the symbiotic star AG dra during 1979–1995

Viotti, R.; González‐Riestra, R.; Montagni, F.; Mattei, J. A.; Maesano, M.; Greiner, J.; Friedjung, M.; Altamore, A.

doi:10.1007/bfb0102269

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…The archival photometric history of AG Dra is particularly interesting. For instance, ten major outbursts have been recorded for AG Dra, with a V of 2 mag, between 1890 and 1960 (Robinson 1969) at intervals of roughly 14 to 15 years (Viotti et al 1983;Mikolajewska et al 1995;Tomov & Tomova 2002;Leedjärv et al 2004, hereafter L04; Gális et al 2004;Viotti et al 2007;Skopal et al 2007). The major events are double-peaked, with interburst intervals of ≈1 yr.…”

Section: Introductionmentioning

confidence: 99%

The spectroscopic evolution of the symbiotic star AG Draconis

Shore

Wahlgren

Genovali³

et al. 2010

A&A

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Context. AG Dra is one of a small group of low metallicity S-type symbiotic binaries with K-type giants that undergoes occasional short-term outbursts of unknown origin. Aims. Our aim is to study the behavior of the white dwarf during an outburst using the optical Raman lines and other emission features in the red giant wind. The goal is to determine changes in the envelope and the wind of the gainer in this system during a major outburst event and to study the coupling between the UV and optical during a major outburst. Methods. Using medium and high resolution groundbased optical spectra and comparisons with archival FUS E and HS T/S T IS spectra, we study the evolution of the

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Section: Introductionmentioning

confidence: 99%

The spectroscopic evolution of the symbiotic star AG Draconis

Shore

Wahlgren

Genovali³

et al. 2010

A&A

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Hydrogen and helium emission of the symbiotic binary AG Draconis during an active phase (1996–1997)

Tomov

Tomova

2002

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Abstract. High resolutions observations of the regions of the Hα and He ii 4868 lines of the symbiotic star AG Dra were performed during its time of activity in 1996-1997. Profiles, fluxes and radial velocity data of these lines as well as the line He i 4713 were obtained. The Hα fluxes changed in correlation with the optical light. The emission measure of the circumbinary nebula of the system at several epochs during its 1994-1998 active phase was also calculated using Balmer continuum emission on the basis of U photometric data from the literature. It was increased by factors up to 36 above its quiescent maximal value. After the 1996 and 1997 light maxima the profile of the He ii 4868 line contained a broad emission component indicating mainly a stellar wind from the hot secondary with a velocity of 1100 ÷ 1300 km s −1 . The mass-loss rate of this star was estimated to be about 1 ÷ 2 10 −7 (d/1.7 kpc) 3/2 M yr −1 . The growth of its Lyman luminosity however is not sufficient to explain the increased nebular emission during the active phase. A view that this emission could be the result of both a rise of the mass-loss rate of the cool giant of the system and a rise of the Lyman flux of the hot luminous secondary, being in a steady-state burning regime during the quiescence, is discussed.

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Luminous binary supersoft X-ray sources: Optical colors and absolute magnitudes

Šimon

2003

A&A

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Abstract. An analysis of the color indices and absolute magnitudes M V0 of the "classical" supersoft X-ray binary sources (SSXBs), the V Sge-type stars (VSs), the symbiotic SSXBs, and the classical novae in the soft X-ray phase is presented. This approach can help comparing the properties and configuration of the reprocessing medium in the individual systems. The range of M V0 of the individual objects is very large, from M V0 = 8.5 to M V0 = −4, most systems having M V0 < 2. The objects with the orbital period P orb < 4 days tend to possess brighter M V0 with the increasing P orb . The same trend is apparent also for M U0 . There is no systematic difference between the classical SSXBs and the VSs, as regards their M V0 and M U0 . The soft X-ray phase of the novae V 1974 Cyg and V 382 Vel occurred at significantly brighter M V0 than those of most other SSXBs while M V0 of the recurrent nova U Sco was comparable to the SSXBs of the comparable P orb . We showed that the luminosity of the reprocessing medium in the symbiotic SSXBs does not increase much with P orb , when compared with the luminosity of the classical SSXBs and VSs; this speaks against large disks in these symbiotics. The classical SSXBs and the VSs have colors very similar each to other and form closed groups in the color-color diagrams. A Balmer jump occurs frequently in emission as inferred from the colors. The correlation between the bolometric luminosity, determined from the X-ray spectra and M V0 or M U0 of all kinds of the SSXBs is rather weak, but resolvable, and is more prominent for M U0 . The implications for the reprocessing medium are discussed.

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Multiwavelength observations of the symbiotic star AG dra during 1979–1995

Cited by 4 publications

References 7 publications

The spectroscopic evolution of the symbiotic star AG Draconis

The spectroscopic evolution of the symbiotic star AG Draconis

Hydrogen and helium emission of the symbiotic binary AG Draconis during an active phase (1996–1997)

Luminous binary supersoft X-ray sources: Optical colors and absolute magnitudes

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