Galactic members in the New Online Database of Symbiotic Variables.

Merc, Jaroslav; Gális, R.; Wolf, M.

doi:10.31577/caosp.2020.50.2.426

Cited by 3 publications

(6 citation statements)

References 12 publications

(12 reference statements)

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“…It is obvious that the He II/H β ratio also varies with the orbital phase and these variations are in an anti-correlation with the photometric changes of AG Dra during quiescence stages. Adopting the formula given by Iijima (1981), we used the ratio of the He II λ 4686 Å and H β emission line EWs as a proxy to the temperature of the hot component in AG Dra (Leedjärv et al, 2004(Leedjärv et al, , 2016Merc et al, 2017). For this reason, the WD's temperature thus determined is also apparently changing with the orbital phase.…”

Section: Orbital Dependence Of the He II And H β Ratiomentioning

confidence: 99%

See 1 more Smart Citation

Recent outburst activity of the symbiotic binary AG Draconis

Merc¹,

Gális²,

Leedjärv³

2018

Proceedings of the Golden Age of Cataclysmic Variables and Related Objects IV — PoS(GOLDEN 2017)

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The symbiotic binary AG Dra regularly undergoes quiescent and active stages which consist of several outbursts repeating with about 360 d interval. The recent outburst activity of AG Dra started by the minor outburst in the late spring of 2015 and was definitely confirmed by the outbursts in April 2016 and May 2017. In the presented work, the photometric and spectroscopic behaviour of the recent outburst activity of AG Dra is presented in detail. Moreover, the temperature of the white dwarf in AG Dra is studied based on the behaviour of the prominent emission lines. We show that a disentanglement of particular effects in the observed changes of the emission lines is crucial to investigate the intrinsic white dwarf temperature variations related to outburst activity of this strongly interacting binary. We also report the effects of the low excitation lines orbital variations and of the H β absorption component on their equivalent widths as well as consequences of the approximations used in our previous works.

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Section: Orbital Dependence Of the He II And H β Ratiomentioning

confidence: 99%

“…The amplitude of the outbursts is from 1 -1.4 mag in the V filter to 3.6 mag in the U filter (Leedjärv et al, 2016). The active stages occur in intervals of 9 -15 years (in 1936, 1951, 1966, 1980, 1994, 2006 and 2015; see figure 1 in Merc et al, 2017).…”

Section: Introductionmentioning

confidence: 97%

Recent outburst activity of the symbiotic binary AG Draconis

Merc¹,

Gális²,

Leedjärv³

2018

Proceedings of the Golden Age of Cataclysmic Variables and Related Objects IV — PoS(GOLDEN 2017)

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“…Since JD 2 458 518, there were no other significant brightenings detected in the case of Gaia18aen. The amplitude of the outbursts and their duration resemble the behavior of typical classical symbiotic stars (e.g., AG Dra, Z And; see, e.g., Mikołajewska et al 1995;Mikołajewska & Kenyon 1996;Merc et al 2019;Munari 2019). Multiple outbursts with timescales similar to those observed in Gaia18aen are also predicted by some nova models (Hillman et al 2014).…”

Section: Hot Component and Outburst Activitymentioning

confidence: 51%

“…The dotted solid curves are steady models of Nomoto et al (2007). González-Riestra et al 1999;Leedjärv et al 2016;Merc et al 2019).…”

Section: Hot Component and Outburst Activitymentioning

confidence: 99%

Gaia18aen: First symbiotic star discovered by Gaia

Merc

Mikołajewska

Gromadzki

et al. 2020

A&A

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Context. Besides the astrometric mission of the Gaia satellite, its repeated and high-precision measurements also serve as an all-sky photometric transient survey. The sudden brightenings of the sources are published as Gaia Photometric Science Alerts and are made publicly available, allowing the community to photometrically and spectroscopically follow up on the object. Aims. The goal of this paper is to analyze the nature and derive the basic parameters of Gaia18aen, a transient detected at the beginning of 2018. This object coincides with the position of the emission-line star WRAY 15-136. The brightening was classified as a “nova?” on the basis of a subsequent spectroscopic observation. Methods. We analyzed two spectra of Gaia18aen and collected the available photometry of the object covering the brightenings in 2018 and also the preceding and following periods of quiescence. Based on this observational data, we derived the parameters of Gaia18aen and discussed the nature of the object. Results. Gaia18aen is the first symbiotic star discovered by Gaia satellite. The system is an S-type symbiotic star and consists of an M giant of a slightly super-solar metallicity, where Teff ∼ 3500 K, a radius of ∼230 R⊙, and a high luminosity L ∼ 7400 L⊙. The hot component is a hot white dwarf. We tentatively determined the orbital period of the system ∼487 d. The main outburst of Gaia18aen in 2018 was accompanied by a decrease in the temperature of the hot component. The first phase of the outburst was characterized by the high luminosity L ∼ 27 000 L⊙, which remained constant for about three weeks after the optical maximum, later followed by the gradual decline of luminosity and increase of temperature. Several re-brightenings have been detected on the timescales of hundreds of days.

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“…However, Gutierrez-Moreno & Moreno (1996), Pereira et al (1998), Mürset & Schmid (1999), Pereira et al (2005), Kogure & Leung (2007), Stoyanov et al (2020) had conducted research on the spectral characteristics of S-type, D-type and D′-type symbiotic stars. The latest list of symbiotic stars was summarized by Merc et al (2020), with 275 symbiotic stars and 119 symbiotic stars candidates in the galaxy. Although the number of observed symbiotic stars is increasing, the number of observed symbiotic stars differs significantly from what was predicted.…”

Section: Introductionmentioning

confidence: 99%

Identifying Symbiotic Stars with Machine Learning

Y.‐d.

Guo

Zhu

et al. 2023

Res. Astron. Astrophys.

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Symbiotic stars are interacting binary systems, making them valuable for studying various astronomical phenomena, such as stellar evolution, mass transfer, and accretion processes. Despite recent progress in the discovery of symbiotic stars, a significant discrepancy between the observed population of symbiotic stars and the number predicted by theoretical models. To bridge this gap, this study utilized machine learning techniques to efficiently identify new symbiotic stars candidates. Three algorithms (XGBoost, LightGBM, and Decision Tree) were applied to a dataset of 198 confirmed symbiotic stars and the resulting model was then used to analyze data from the LAMOST survey, leading to the identification of 11,709 potential symbiotic stars candidates. Out of the these potential symbiotic stars candidates listed in the catalog, 15 have spectra available in the SDSS survey. Among these 15 candidates, two candidates, namely V* V603 Ori and V* GN Tau, have been confirmed as symbiotic stars. The remaining 11 candidates have been classified as accreting-only symbiotic star candidates. The other two candidates, one of which has been identified as a galaxy by both SDSS and LAMOST surveys, and the other identified as a quasar by SDSS survey and as a galaxy by LAMOST survey.

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Galactic members in the New Online Database of Symbiotic Variables.

Cited by 3 publications

References 12 publications

Recent outburst activity of the symbiotic binary AG Draconis

Recent outburst activity of the symbiotic binary AG Draconis

Gaia18aen: First symbiotic star discovered by Gaia

Identifying Symbiotic Stars with Machine Learning

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