Mathematical Modelling of Astrophysical Objects and Processes

Андронов, И. Л.; Breus, V. V.; Kudashkina, L. S.

doi:10.30525/978-9934-588-86-0.01

Cited by 3 publications

(3 citation statements)

References 39 publications

(24 reference statements)

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“…The software MAVKA has been widely used in this work. Previous investigation and development of the MAVKA algorithms were made in [2,5,6,11,12]. The final version of the software contains nine methods of approximation.…”

Section: Analysis Of the Mavka Processing Resultsmentioning

confidence: 99%

Third components with elliptical orbits in the eclipsing binaries: AB Cas, AF Gem, AR Boo, BF Vir and CL Aur

Tvardovskyi¹

2021

Adv.Astron.Spa.Physics

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In this research, five eclipsing binary stars were studied: AB Cas, AF Gem, AR Boo, BF Vir and CL Aur. The large sets of moments of minima were used: from the international BRNO database and amateur observations from the database AAVSO. Firstly, moments of minima for AAVSO observations were obtained (totally - 222 minima). The software MAVKA was used and approximation with various methods was done in order to find the best fit. Then all obtained moments of minima were combined and O-C diagrams were plotted. For all stars these diagrams represented sinusoidal-like oscillations with superposition of parabolic trend. One of the possible reasons for such oscillations could be presence of well-known light-time effect (LTE) caused by third component with elliptical orbit. Parabolic trend was explained as mass transfer between components of binary system. For all these stars we computed possible mass of the third component, orbital elements, mass transfer rate and errors for all computed values.

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Section: Analysis Of the Mavka Processing Resultsmentioning

confidence: 99%

Third components with elliptical orbits in the eclipsing binaries: AB Cas, AF Gem, AR Boo, BF Vir and CL Aur

Tvardovskyi¹

2021

Adv.Astron.Spa.Physics

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“…Periodogram Analysis was made using the trigonomeric polynomial least square approximations of orders s = 1, 2 and 4. The test function S(f ) is the ratio of the variance of the approximation to the variance of observations (Andronov 1994(Andronov , 2020Andronov et al, 2020). The algorithm was realized in the software MCV (Andronov and Baklanov, 2004).…”

Section: Periodogram Analysismentioning

confidence: 99%

R Scuti: Close Alternating Pulsation Periods or Chaos in the RV Tau -- Type Star?

Kudashkina,

Andronov

2021

Preprint

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Results of analysis of 60 010 data photometric observations from the AAVSO international database are presented, which span 120 years of monitoring. The periodogram analysis shows the best fit period of 70.74d, a half of typically published periods for smaller intervals. Contrary to expectation for deep/shallow minima, the changes between them are not so regular. There may be series of deep (or shallow) minima without alternations. There may be two acting periods of 138.5 days and 70.74, so the beat modulation may be expected. The dependence of the phases of deep minima argue for two alternating periods with a characteristic life-time of a mode of 30years. These phenomenological results better explain the variability than the model of chaos.

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“…There are dozens of types of variability and hundreds of combinations, so there are some basic principles instead of a single method, There are numerous reviews on step-by-step improvements and extensions of the methods (Andronov (1994), Andronov (2003), Andronov (2005), Andronov (2020), Andronov et al (2020a)).…”

Section: Why Phenomenological Modelling?mentioning

confidence: 99%

Astroinformatics: Statistically Optimal Approximations of Near-Extremal Parts with Application to Variable Stars

Андронов

Andrych

Chinarova

et al. 2020

ComBAO

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The software MAVKA is described, which was elaborated for statistically optimal determination of the characteristics of the extrema of 1000+ variable stars of different types, mainly eclipsing and pulsating. The approximations are phenomenological, but not physical. As often, the discovery of a new variable star is made on time series of a single-filter (single-channel) data, and there is no possibility to determine parameters needed for physical modelling (e.g. temperature, radial velocities, mass ratio of binaries). Besides classical polynomial approximation "AP" (we limited the degree of the polynomial from 2 to 9), there are realized symmetrical approximations (symmetrical polynomials "SP", "wall-supported" horizontal line "WSL" and parabola "WSP", restricted polynomials of non-integer order based on approximations of the functions proposed by Andronov (2012) and Mikulasek (2015) and generally asymmetric functions (asymptotic parabola "AP", parabolic spline "PS", generalized hyperbolic secant function "SECH" and "log-normal-like" "BSK"). This software is a successor of the "Observation Obscurer" with some features for the variable star research, including a block for "running parabola" "RP" scalegram and approximation. Whereas the RP is oriented on approximation of the complete data set. MAVKA is pointed to parts of the light curve close to extrema (including total eclipses and transits of stars and exoplanets). The functions for wider intervals, covering the eclipse totally, were discussed in Andronov (2017). Global and local approximations are reviewed in Andronov (2020). The software is available at http://uavso.org.ua/mavka and https://katerynaandrych.wixsite.com/mavka. We have analyzed the data from own observations, as well as from monitoring obtained at ground-based and space (currently, mainly, TESS) observatories. It may be used for signals of any nature.

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Mathematical Modelling of Astrophysical Objects and Processes

Cited by 3 publications

References 39 publications

Third components with elliptical orbits in the eclipsing binaries: AB Cas, AF Gem, AR Boo, BF Vir and CL Aur

Third components with elliptical orbits in the eclipsing binaries: AB Cas, AF Gem, AR Boo, BF Vir and CL Aur

R Scuti: Close Alternating Pulsation Periods or Chaos in the RV Tau -- Type Star?

Astroinformatics: Statistically Optimal Approximations of Near-Extremal Parts with Application to Variable Stars

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