Modelling of W UMa-type variable stars

Skelton, P.L.I.; Smits, Derck P.

doi:10.4102/sajs.v105i3/4.62

Cited by 8 publications

(7 citation statements)

References 23 publications

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“…A shape of the phase diagram is typical of diagrams of contact binary stars. The difference between the primary and secondary minima is around 0.039 mag (usually this difference is no more than 0.1 or 0.2 magnitudes (Skelton and Smits 2009). The difference between maximum and minimum is 0.3558 mag (typically it is of the order of 0.75 mag (Skelton and Smits 2009).…”

Section: Eclipsing Binary Candidate Tyc 2764-1997-1mentioning

confidence: 98%

“…As we obtained a larger value for the orbital period than Hoffman et al (2009), there is a possibility that the orbital period of the system has changed since 2009 either due to the redistribution of matter between the stars, or due to the loss of angular momentum. In case of the conservative mass exchange, the period increases if mass is transferred from the less massive to the more massive star (Skelton and Smits 2009). A shape of the phase diagram is typical of diagrams of contact binary stars.…”

Section: Eclipsing Binary Candidate Tyc 2764-1997-1mentioning

confidence: 99%

See 1 more Smart Citation

Search for variable stars in the northern sky: analysis of photometric time series for 3598 stars

Pakštienė

Janulis

Drazdauskas

et al. 2019

Astrophys Space Sci

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As extensive ground-based observations and characterisation of different variable stars are of the utmost importance in preparing optimal input catalogues for space missions, our aim was to search for new variable stars in selected fields of the northern sky. We obtained 24 470 CCD images and analysed photometric time series of stars using the DAOPHOT based package Muniwin as the first step, and the Period04 package was used to further analyse the suspected new variable stars. The light curves and other observational results are presented for 3598 stars online. We found 81 new variable stars, among them is an eclipsing binary with a variable component and possibly eccentric orbits TYC4038-693-1 which we also observed spectroscopically, four δ Scuti candidates, six other variable stars with periods falling into the interval of 35 minutes to 20 days. Furthermore, we identified 70 slowly varying stars with so far undefined periodicity. Additional photometric and spectral observations were carried out

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Section: Eclipsing Binary Candidate Tyc 2764-1997-1mentioning

confidence: 98%

Section: Eclipsing Binary Candidate Tyc 2764-1997-1mentioning

confidence: 99%

Search for variable stars in the northern sky: analysis of photometric time series for 3598 stars

Pakštienė

Janulis

Drazdauskas

et al. 2019

Astrophys Space Sci

View full text Add to dashboard Cite

show abstract

“…Differences in minima are usually a sign that the temperatures of both stars in the system are different. Light curves of type EW show a continual behavior, similar to EB types, but the minima are deeper than EB, and their absolute difference is small (Skelton, 2009).…”

Section: Introductionmentioning

confidence: 84%

Automatic classification of eclipsing binary stars using deep learning methods

Čokina,

Maslej-Krešňáková,

Butka

et al. 2021

Preprint

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In the last couple of decades, tremendous progress has been achieved in developing robotic telescopes and, as a result, sky surveys (both terrestrial and space) have become the source of a substantial amount of new observational data. These data contain a lot of information about binary stars, hidden in their light curves. With the huge amount of astronomical data gathered, it is not reasonable to expect all the data to be manually processed and analyzed. Therefore, in this paper, we focus on the automatic classification of eclipsing binary stars using deep learning methods. Our classifier provides a tool for the categorization of light curves of binary stars into two classes: detached and over-contact. We used the ELISa software to obtain synthetic data, which we then used for the training of the classifier. For evaluation purposes, we collected 100 light curves of observed binary stars, in order to evaluate a number of classifiers. We evaluated semi-detached eclipsing binary stars as detached.The best-performing classifier combines bidirectional Long Short-Term Memory (LSTM) and a one-dimensional convolutional neural network, which achieved 98% accuracy on the evaluation set. Omitting semi-detached eclipsing binary stars, we could obtain 100% accuracy in classification.

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“…In the astrophysics parlance, the temperature range considered roughly corresponds to the F spectral class. Contact binaries from these earlier spectral types are thought to form a different subclass of overcontact binaries, called the A-type W UMa stars [72]. A list of ten stars with the values of their parameters and their calculated measures from this restricted sub-population is shown in Table 2.…”

Section: Correlations With Degree Of Contactmentioning

confidence: 99%

Fractal measures and nonlinear dynamics of overcontact binaries

George

Misra

Ambika

2020

Communications in Nonlinear Science and Numerical Simulation

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Overcontact binary stars are systems of two stars where the component stars are in contact with each other. This implies that they share a common envelope of gas. In this work we seek signatures of nonlinearity and chaos in these stars by using time series analysis techniques. We use three main techniques, namely the correlation dimension, f (α) spectrum and the bicoherence. The former two are calculated from the reconstructed dynamics, while the latter is calculated from the Fourier transforms of the time series of intensity variations(light curves) of these stars. Our dataset consists of data from 463 overcontact binary stars in the Kepler field of view [1]. Our analysis indicates nonlinearity and signatures of chaos in almost all the light curves. We also explore whether the underlying nonlinear properties of the stars are related to their physical properties like fill-out-factor, a measure of the extend of contact between the components of an overcontact binary system . We observe that significant correlations exist between the fill out factor and the nonlinear quantifiers. This correlation is more pronounced in specific subcategories constructed based on the mass ratios and effective temperatures of the binaries. The correlations observed can be indicative of variations in the nonlinear properties of the star as it ages. We believe that this study relating nonlinear and astrophysical properties of binary stars is the first of its kind and is an important starting point for such studies in other astrophysical objects displaying nonlinear dynamical behaviour. binary or variable [17]. Eclipsing binaries are further classified morphologically as detached and close binary star systems. Close binary systems exhibit thermal contact and have the ability to exhibit mass transfer. This offers the prospect of understanding many interesting physical phenomena like stellar mergers, thermal relaxation oscillations, magnetic stellar winds etc [18,19,20]. After the observation of a merger event in 2008 in V1309 Scorpii, considerable speculation on future merger events have lead to a deepened interest in these systems [18,21,22,23].Overcontact binaries, called W UMa stars after their prototype, are a subclass of close binary stars which shares a common envelope of gas. They are characterized by both components of the binary star exceeding their Roche lobes, implying that the companion stars are in physical contact with each other [24]. One quantity used to characterize the degree of contact in binary systems, is the fill-out factor, f f [24,25]. The fill-out factor is 0 when the component stars in the binary are just in contact and is 1 when they are in complete contact. When both components exceed their Roche lobes, as in the case of overcontact binary stars, mass and energy transfer can occur in either direction [26,27]. This can lead to changes in periods and stellar mergers leading to red novae [19,18]. While the primary variation in these stars is expected to be due to the orbital motion, many unexplained or partially e...

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Modelling of W UMa-type variable stars

Cited by 8 publications

References 23 publications

Search for variable stars in the northern sky: analysis of photometric time series for 3598 stars

Search for variable stars in the northern sky: analysis of photometric time series for 3598 stars

Automatic classification of eclipsing binary stars using deep learning methods

Fractal measures and nonlinear dynamics of overcontact binaries

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