scholarly journals Spectral Synthesis of Cool Components of Symbiotic Stars

1992 ◽  
Vol 150 ◽  
pp. 409-410
Author(s):  
Claudio B. Pereira ◽  
Sayd Codina Landaberry
Keyword(s):  
Satisfactory Agreement ◽  
Spectral Synthesis ◽  
Optical Spectra ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Cool Component ◽  
Synthesis Technique ◽  
Solar Abundances

We analyzed the optical spectra of cool component of symbiotic star SY Mus by means of spectral synthesis technique in order to derive the atomic abundances using the Minneart formulae for computing the atmospheric opacities. We obtained a satisfactory agreement between the observed and computed spectra and the resulting abundances were consistent to the solar abundances.

Relaxation Oscillations in Red-Giant Envelopes and the Symbiotic Stars

1973 ◽  
Vol 2 (4) ◽  
pp. 198-200 ◽  
Author(s):  
P. R. Wood
Keyword(s):  
Absorption Spectrum ◽  
Light Curves ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Relaxation Oscillations ◽  
Cool Component ◽  
Cool Star ◽  
Red Giant ◽  
Eruptive Behaviour

The spectrum of a symbiotic star consists of an M-type absorption spectrum, a B-type shell spectrum and nebula emission lines, the relative contributions of these three components varying with time. The light curves of the symbiotic stars vary with a semi-regular period typically 200-800 days while larger eruptions occur on a timescale of ~ 3.5 years. Some suggestions which have been advanced to explain the combination spectrum, variability and eruptive behaviour of the symbiotic stars are: (a)the symbiotic stars are binaries consisting of a hot and cool component.(b)the symbiotic stars consist of a single hot star surrounded by a large optically thick envelope giving the appearance of a hot continuum with the absorption spectrum of a cool star superimposed on it.(c)the symbiotic stars are single stars surrounded by a shock wave heated chromosphere.Although some of the symbiotic stars are undoubtedly binaries (for example, T Coronae Borealis), observatienal evidence suggests that others may be explained by hypothesis (c) above. The calculations described below provide an explanation of the symbiotic stars in conjunction with hypothesis (c).

Spectroscopic Monotoring of the Symbiotic Star BX Monocerotis

2012 ◽  
Vol 21 (1-2) ◽  
Author(s):  
G. C. Anupama ◽  
U. S. Kamath ◽  
U. K. Gurugubelli ◽  
J. Mikołajewska
Keyword(s):  
Optical Spectra ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Low Resolution ◽  
Cool Component

AbstractLow resolution optical spectra of the symbiotic star BX Monocerotis in the 3500-9000 Å range obtained during 1999–2010 are described. the spectrum of BX Mon at all phases is dominated by the cool component, with a red continuum and TiO absorption. Emission lines, predominantly due to HI, He I, He II, Fe II, Ca II and [O III] are seen superimposed on the spectrum of the M5III star, with variable intensities. the observed variations in the spectra seem to be correlated with the orbital phases.

Discovery of five new Galactic symbiotic stars in the VPHAS+ survey

2021 ◽  
Vol 502 (2) ◽  
pp. 2513-2517
Author(s):  
Stavros Akras ◽  
Denise R Gonçalves ◽  
Alvaro Alvarez-Candal ◽  
Claudio B Pereira
Keyword(s):  
Spectroscopic Data ◽  
Selection Criterion ◽  
Optical Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Symbiotic Stars ◽  
Selection Of

ABSTRACT We report the validation of a recently proposed infrared (IR) selection criterion for symbiotic stars (SySts). Spectroscopic data were obtained for seven candidates, selected from the SySt candidates of Akras et al. by employing the new supplementary IR selection criterion for SySts in the VST/OmegaCAM Photometric H-Alpha Survey. Five of them turned out to be genuine SySts after the detection of H α, He ii, and [O iii] emission lines as well as TiO molecular bands. The characteristic O vi Raman-scattered line is also detected in one of these SySts. According to their IR colours and optical spectra, all five newly discovered SySts are classified as S-type. The high rate of true SySts detections of this work demonstrates that the combination of the H α emission and the new IR criterion improves the selection of target lists for follow-up observations by minimizing the number of contaminants and optimizing the observing time.

scholarly journals Ultraviolet Variability of the Symbiotic Star AG PEG

1988 ◽  
Vol 103 ◽  
pp. 263-264
Author(s):  
D. Chochol ◽  
Z. Komárek ◽  
A. Vittone
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
High Dispersion ◽  
Symbiotic Star ◽  
Observational Material

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

scholarly journals Ultraviolet properties of the symbiotic stars

1982 ◽  
Vol 70 ◽  
pp. 103-113
Author(s):  
Mark H. Slovak ◽  
David L. Lambert
Keyword(s):  
High Resolution ◽  
Broad Band ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Interim Report

Prior to the launch of the IDE satellite in early 1978, the only symbiotic star previously detected in the ultraviolet by earlier UV satellites, such as the 0A0-2, TD-1 and ANS experiments, was AG Pegasi = HD 207757 (Gallager et al. 1979). These broad-band observations indicated that the symbiotics as a class may show a significant ultraviolet flux and thus they became natural candidates for a survey with the IUE satellite. The following is an interim report on a survey of the symbiotics, both at low and, for AG Pegasi and CH Cygni, at high resolution.

Symbiotic Stars in the Local Group of Galaxies: POINT-AGAPE Catalogue Revisited

2017 ◽  
Vol 14 (S339) ◽  
pp. 291-294
Author(s):  
K. Drozd ◽  
J. Mikołajewska ◽  
M. Darnley ◽  
K. Iłkiewicz ◽  
N. Caldwell ◽  
...  
Keyword(s):  
Light Curve ◽  
Local Group ◽  
Light Curves ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Original Point

AbstractThis research was prompted by the discovery of 35 new or candidate symbiotic stars during a targeted search in the Local Group of Galaxies. A catalogue of a further 200 or so such objects has now been compiled. Many of them could be identified with counterparts in the POINT-AGAPE Catalogue. However, information in the Catalogue is limited to position, brightness and possible period, and light-curves are not available. The poster presented an example of a light-curve of a symbiotic star retrieved from original Point-Agape Catalogue data.

The nova type outburst of the symbiotic star AS 296

1990 ◽  
Vol 122 ◽  
pp. 440-441
Author(s):  
Ulisse Munari
Keyword(s):  
Orbital Period ◽  
Active Phase ◽  
Borderline Case ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Late Type ◽  
Type Giant ◽  
One Year

AbstractThe photometric and spectroscopic evolutions, displayed by AS 296 since the June 1988 outburst ([1]), are presented and discussed. The main features of the model outlined by [2], [3] and [4], are confirmed and further developped. An orbital period of about 3 years is inferred from Hα modulation (see [5]).The outburst originated from a TNR event in the accreted envelope of a WD. The IUE and optical spectroscopic evolution agrees with the expected scenario for degenerate conditions in the accreted material, while the high quiescence luminosity of the WD would indicate nondegenerate conditions.The late type giant passed unchanged the outburst. Also the region of Hα formation was not touched by the eruption.After one year the system has not yet reached the quiescence again. The photometric evolution displayed by AS 296 up to June 15, 1989 is presented in Fig.1.In Tab.1, the main features exhibited by symbiotic stars that have experienced a TNR event are summarized. The first 8 objects in the table are usually collectively called "symbiotic novae". They distinguish themselves for the very long outburst duration. At present, AS 296 appears to be a borderline case of such class, and a firm understanding needs to wait for the end of current active phase.

scholarly journals Symbiotic star UV emission and theoretical models

1982 ◽  
Vol 70 ◽  
pp. 269-272
Author(s):  
M. Kafatos
Keyword(s):  
Line Emission ◽  
Theoretical Models ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Uv Emission

Observations of symbiotic stars in the far UV have provided important information on the nature of these objects. The canonical spectrum of a symbiotic star, e.g. RW Hya, Z And, AG Peg, is dominated by strong allowed and semiforbidden lines of a variety of at least twice ionized elements. Weaker emission from neutral and singly ionized species is also present. The Mg II doublet is usually very strong and may be associated with the M giant primary. A continuum may or may not be present in the 1200 - 2000 A range but is generally present in the range 2000 - 3200 A range, the latter arising from free-free and bound-free emission in the same nebula that is responsible for the UV line emission (CI Cyg, RW Hya, RX Pup). The suspected hot subdwarf continuum is seen in some cases in the range 1200 - 2000 A (RW Hya, AG Peg, SY Mus).

scholarly journals Details of the Classification of Symbiotic Stars: The Case of the Symbiotic Nova AG Peg

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
A. A. Tatarnikova ◽  
M. A. Burlak ◽  
D. V. Popolitova ◽  
T. N. Tarasova ◽  
A. M. Tatarnikov
Keyword(s):  
Component Model ◽  
Symbiotic Stars ◽  
Cool Component ◽  
Photometric Observations

AbstractWe analyze archival and modern spectroscopic and photometric observations of the oldest known symbiotic nova AG Peg. Its new outburst (which began in 2015 June) differs greatly from the first one (which occurred in the mid-1850s). Fast photometric evolution of the new outburst is similar to that of Z And-type outbursts. However, the SED of AG Peg during the 2015 outburst, as well as during the quiescence, can be fitted by a standard three-component model (cool component + hot component + nebula), which is not common for an Z And-type outburst.

scholarly journals Spectroscopic observations of AG Dra

1982 ◽  
Vol 70 ◽  
pp. 185-189
Author(s):  
Huang Chang-Chun
Keyword(s):  
Radial Velocity ◽  
Spectral Type ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Spectroscopic Observations ◽  
Very High

AG Dra is an interesting symbiotic star, on account of its very high negative velocity and its earlier spectral type among the symbiotic stars. This star has been classified as dG7 (Wilson,1943), K1 II (Roman,1953) and K3 III (Boyarchuk,1966). It has a variable radial velocity.During summer 1981, spectroscopic observations of AG Dra were performed at the Haute-Provence Observatory using the Marly spectrograph with a dispersion of 80 A mm-1 at the 120 cm telescope and using the Coudé spectrograph of the 193 cm telescope with a dispersion of 40 A mm-1. Professor Ch. Fehrenbach very kindly given me a plate of the star which he had taken in July,1966, using the coudé spectrograph of the 193 cm telescope with a dispersion of 40 A mm-1.

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