Period Changes of Close Binary Systems

Rovithis‐Livaniou, H.

doi:10.1007/s10509-005-4385-3

Cited by 3 publications

(2 citation statements)

References 28 publications

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“…Our knowledge of period changes in close binaries is mainly and almost exclusively based on EBs and especially on the analysis of their (O-C) diagrams, which carry much and valuable information. Thus, it is very important to distinguish the apparent from the real orbital period variations [75], while it is also very important the way with which such a diagram is constructed and analysed.…”

Section: Period Variationsmentioning

confidence: 99%

Study of Eclipsing Binaries: Light Curves & O-C Diagrams Interpretation

Rovithis‐Livaniou

2020

Galaxies

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The continuous improvement in observational methods of eclipsing binaries, EBs, yield more accurate data, while the development of their light curves, that is magnitude versus time, analysis yield more precise results. Even so, and in spite the large number of EBs and the huge amount of observational data obtained mainly by space missions, the ways of getting the appropriate information for their physical parameters etc. is either from their light curves and/or from their period variations via the study of their (O-C) diagrams. The latter express the differences between the observed, O, and the calculated, C, times of minimum light. Thus, old and new light curves analysis methods of EBs to obtain their principal parameters will be considered, with examples mainly from our own observational material, and their subsequent light curves analysis using either old or new methods. Similarly, the orbital period changes of EBs via their (O-C) diagrams are referred to with emphasis on the use of continuous methods for their treatment in absence of sudden or abrupt events. Finally, a general discussion is given concerning these two topics as well as to a few related subjects.

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Section: Period Variationsmentioning

confidence: 99%

Study of Eclipsing Binaries: Light Curves & O-C Diagrams Interpretation

Rovithis‐Livaniou

2020

Galaxies

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“…Indeed, recent otherwise excellent accounts and reviews of EB ephemeris work (e.g. Kreiner et al 2001;Rovithis-Livaniou 2005) do not mention the idea. Accordingly, inclusion within this review may foster awareness, whose present lack is likely due to the concept's rather quiet introduction in two independent developments -so quiet that the early conceptual work can be traced only through applications, with the two camps becoming aware of each others work only recently.…”

Section: Whole Light and Velocity Curve Ephemerides And Extension To mentioning

confidence: 99%

Close Binary Star Observables: Modeling Innovations 2003-06

Wilson

2006

Proc. IAU

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Abstract. Innovative work on close binary models in 2003-06 improved upon synthesized line spectra, line profiles, and polarimetry; developed new ways of parameter estimation; and increased solution effectiveness and efficiency. Recent applications demonstrate the analytic power of binary system line spectrum models that pre-date the triennium. X-ray binary line profiles and radial velocity curves were refined by solution of the radiative transfer problem with specific inclusion of X-irradiation. Model polarization curves were generated by Monte Carlo experiments with multiple Thomson scattering in thin and thick binary system disks. In the parameter estimation area, independent developments by two groups now allow measurement of ephemerides, apsidal motion, and third body parameters from whole light and velocity curves, to supplement the traditional way of eclipse timings. Although the new route to those parameters is not well known within the ephemeris community, there are accuracy advantages and the number of applications is increasing. Numerical solution experiments on photometric mass ratios have checked two views of their intuitive basis, and show that mass ratios are well determined where star radii and limiting lobe radii are both well determined, which is for semi-detached or over-contact binaries with total-annular eclipses. Solution efficiency and automatic operation is needed for processing of light curves from large surveys, and will also be valuable for preliminary solutions of individually observed binaries. Neural networks have mainly been used for classification, and now a neural network program reliably finds preliminary solutions for W UMa binaries. Archived model light curves and Fourier fitting also are being pursued for classification and for preliminary solutions. Light curves in physical units such as erg · sec −1 · cm −3 now allow direct distance estimation by combining the absolute accuracy of model stellar atmospheres with the astrophysical detail of a physical close binary model, by means of rigorous scaling between surface emission and observable flux. A Temperature-distance (T-d) theorem specifies conditions under which temperatures of both stars and distance can be found from light and velocity curves.

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Third‐Body Parameters from Whole Light and Velocity Curves

Hamme

Wilson

2007

ApJ

234

145

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Eclipsing binaries can improve multiple system statistics via the light-time effect and radial velocity shifts. Here an algorithm operates on data of mixed type to exploit these opportunities. Main reasons for enhanced reliability are that (1) combined light and velocity curves give better timewise coverage than either type alone, (2) properly weighted solutions impersonally balance light and velocity information, and (3) the entire theory is within the computer model, so observations are used directly without corrections. A brief history of mixed whole-curve solutions is given and the relative importance of light-time and radial velocity input for third-body parameters is discussed and quantified. Period sifting by power spectral analysis is essentially indispensable in preliminary work. Applications are to the Algol-type system DM Persei and the detached system VV Orionis. An assumption of coplanarity for DM Per's inner and outer orbits is tested and quantified by dynamical experiments. Derived third-body parameters for DM Per are mainly reasonable and self-consistent. For comparison with whole-curve results, we also investigated DM Per's ephemeris in terms of eclipse timings and found whole-curve solutions to give smaller standard errors in reference epoch (T 0 ), binary orbit period (P), and dP/dt, over a similar baseline in time. An astonishing outcome is lack of evidence that can pass reasonable validity tests for VV Ori's well-accepted third star with P % 120 days. Estimates of third light do indicate a third star, but the correct period cannot now be established, so the star cannot be identified as the one heretofore recognized from radial velocity evidence. The much cited 120 day period appears to be an artifact of the window function for VV Ori's historical velocity observations.

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Period Changes of Close Binary Systems

Abstract: A brief review of the physical mechanisms that could produce the observed orbital period changes in close binaries, the methods used to study them, and a general discussion is given.

Cited by 3 publications

References 28 publications

Study of Eclipsing Binaries: Light Curves & O-C Diagrams Interpretation

Study of Eclipsing Binaries: Light Curves & O-C Diagrams Interpretation

Close Binary Star Observables: Modeling Innovations 2003-06

Third‐Body Parameters from Whole Light and Velocity Curves

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