Apsidal motion in the early-type eclipsing binaries CW Cephei, Y Cygni and AG Persei*

Giménez, Á.; Kim, Chun-Hwey; Nha, Il-Seong

doi:10.1093/mnras/224.3.543

Cited by 21 publications

(22 citation statements)

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“…3. More details about the apsidal-motion solution and the comparison of the present result with the previous studies of apsidal A120, page 6 of 12 Giménez et al (1987) and Holmgren et al (1995) can be found in a recent conference paper by Wolf et al (2013).…”

Section: Apsidal Motion From the Analysis Of The Observed Times Of MIsupporting

confidence: 70%

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Harmanec

Holmgren²,

Wolf

et al. 2014

A&A

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Context. Rapid advancements in light-curve and radial-velocity curve modelling, as well as improvements in the accuracy of observations, allow more stringent tests of the theory of stellar evolution. Binaries with rapid apsidal advance are particularly useful in this respect since the internal structure of the stars can also be tested. Aims. Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornerstones of critical tests of stellar evolutionary theory for massive stars. Nevertheless, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyse all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. Methods. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analysed earlier obtained blue electronic spectra. Reduction of the new spectra was carried out in the IRAF and SPEFO programs. Orbital elements were derived independently with the FOTEL and PHOEBE programs and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE. Results. Our analyses provide the most accurate value of the apsidal period of (47.805 ± 0.030) yr published so far and the following physical elements: M 1 = 17.72 ± 0.35 M , M 2 = 17.73 ± 0.30 M , R 1 = 5.785 ± 0.091 R , and R 2 = 5.816 ± 0.063 R . The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k 2 = −1.937. A comparison with Claret's stellar interior models implies an age close to 2 × 10 6 yr for both stars. Conclusions. The claimed accuracy of modern element determination of 1-2 per cent still seems a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.

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Section: Apsidal Motion From the Analysis Of The Observed Times Of MIsupporting

confidence: 70%

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Harmanec

Holmgren²,

Wolf

et al. 2014

A&A

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“…Because of the insufficient coverage of the ephemeris curve, the results for V1147 Cyg and V1094 Tau must be considered preliminary. More than 20 years has elapsed since the last similar studies of several of these binaries by Giménez & Margrave (1985) and Giménez et al (1987). Additional observations will be needed to increase the data coverage of the apsidal motion periods as well as to derive accurate absolute dimensions and orbital parameters.…”

Section: Discussionmentioning

confidence: 99%

“…This study is part of a series of papers on apsidal motion, where we present the results of our long-term photometric monitoring of EEB eclipses (Wolf et al 2001(Wolf et al , 2004(Wolf et al , 2005. Similar studies of relativistic apsidal motion in individual Partly based on photoelectric observations secured at the Hvar Observatory, Faculty of Geodesy, Zagreb, Croatia, in October 2008. binary systems were published by Giménez & Margrave (1985), Giménez et al (1987), and Claret (1997Claret ( , 1998. Regularly updated ephemeris, based on all compiled times of minima, can be found in the database of the O-C diagrams (Kreiner 2004) 1 .…”

Section: Introductionmentioning

confidence: 99%

Relativistic apsidal motion in eccentric eclipsing binaries

Wolf¹,

Claret²,

Kotková

et al. 2010

A&A

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Context. The study of apsidal motion in detached eclipsing binary systems is known to be an important source of information about stellar internal structure as well as the possibility of verifying of General Relativity outside the Solar System. Aims. As part of the long-term Ondřejov and Ostrava observational projects, we aim to measure precise times of minima for eccentric eclipsing binaries, needed for the accurate determination of apsidal motion, providing a suitable test of the effects of General Relativity. Methods. About seventy new times of minimum light recorded with photoelectric or CCD photometers were obtained for ten eccentric-orbit eclipsing binaries with significant relativistic apsidal motion. Their O-C diagrams were analysed using all reliable timings found in the literature, and new or improved elements of apsidal motion were obtained. Results. We confirm very long periods of apsidal motion for all systems. For BF Dra and V1094 Tau, we present the first apsidalmotion solution. The relativistic effects are dominant, representing up to 100% of the total observable apsidal-motion rate in several systems. The theoretical and observed values of the internal structure constant k 2 were compared for systems with lower relativistic contribution. Using the light-time effect solution, we predict a faint third component for V1094 Tau orbiting with a short period of about 8 years.

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“…From these observations, nine eclipse epochs were determined with the method of Kwee & van Woerden (1956, hereafter KW). Six of these have already been published in Giménez et al (1987). The natural-system light curves of CW Cep are shown in Figure 1.…”

Section: Observationsmentioning

confidence: 99%

“…The system is young, belonging to the Cep OB3 association (Blaauw, Hiltner, & Johnson 1959), and its eccentric orbit shows apsidal motion (Nha 1975) with the relatively short period of about 45 years (Giménez, Kim, & Nha 1987;Clausen & Giménez 1991). Abrami & Cester (1960), Nha (1975), Sö derhjelm (1976), Han (1984), Clausen & Giménez (1991), and Soydugan et al (2001) have all observed photoelectric light curves.…”

Section: Introductionmentioning

confidence: 99%

Photometric Studies of CW Cephei

Han

Kim

Lee

et al. 2002

The Astronomical Journal

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Three-filter observations of the hot, detached close binary CW Cephei are used as the basis for light curves dating to the mid-1980s. The ephemeris of apsidal rotation is improved as a result of a lengthier time base. The light-curve synthesis converges to essentially the same orbital and stellar parameters that have been accepted for almost 40 years. For the first time, emphasis is given to a new type of complication confusing the apsidal rotation behavior, and it is shown that this complication is photometric and not dynamical. In addition, we find that the light curve is itself beset by substantial complications, which may be associated with the rather feeble stellar winds.

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Apsidal motion in the early-type eclipsing binaries CW Cephei, Y Cygni and AG Persei*

Cited by 21 publications

References 0 publications

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Relativistic apsidal motion in eccentric eclipsing binaries

Photometric Studies of CW Cephei

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