The<i>α</i>CrB binary system: A new radial velocity curve, apsidal motion, and the alignment of rotation and orbit axes

Schmitt, J. H. M. M.; Schröder, K.-P.; Rauw, Grégor; Hempelmann, A.; Mittag, M.; González‐Pérez, J. N.; Czesla, S.; Wolter, Uwe; Jack, D.

doi:10.1051/0004-6361/201526662

Cited by 16 publications

(17 citation statements)

References 24 publications

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“…(4), r is the radial distance from the centre of the star, ρ(r) is the local density, and ρ (r) is the mean density inside a sphere of radius r (e.g. Sterne 1939;Schmitt et al 2016). Solving the Clairaut-Radau equation applied to the density structure predicted by stellar evolution models thus yields the value of k 2 for a given stellar mass and age.…”

Section: Apsidal Motionmentioning

confidence: 99%

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Apsidal motion in the massive binary HD 152218

Rauw

Rosu

Noels

et al. 2016

A&A

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Massive binary systems are important laboratories in which to probe the properties of massive stars and stellar physics in general. In this context, we analysed optical spectroscopy and photometry of the eccentric short-period early-type binary HD 152218 in the young open cluster NGC 6231. We reconstructed the spectra of the individual stars using a disentangling code. The individual spectra were then compared with synthetic spectra obtained with the CMFGEN model atmosphere code. We furthermore analysed the light curve of the binary and used it to constrain the orbital inclination and to derive absolute masses of (19.8 ± 1.5) and (15.0 ± 1.1) M . Combining radial velocity measurements from over 60 yr, we show that the system displays apsidal motion at a rate of (2.04−.24 )• yr −1 . Solving the Clairaut-Radau equation, we used stellar evolution models, obtained with the CLES code, to compute the internal structure constants and to evaluate the theoretically predicted rate of apsidal motion as a function of stellar age and primary mass. In this way, we determine an age of 5.8 ± 0.6 Myr for HD 152218, which is towards the higher end of, but compatible with, the range of ages of the massive star population of NGC 6231 as determined from isochrone fitting.

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Section: Apsidal Motionmentioning

confidence: 99%

“…A better description is achieved when it is considered that the argument of periastron ω undergoes a secular perturbationω (e.g. Schmitt et al 2016, and references therein). The rate of apsidal motion is directly related to the internal structure of the components of the binary (e.g.…”

Section: Introductionmentioning

confidence: 99%

Apsidal motion in the massive binary HD 152218

Rauw

Rosu

Noels

et al. 2016

A&A

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“…Precise determinations of apsidal motion require long-term monitoring of the times of eclipse, generally spanning several decades, with high-quality measurements, although apsidal motion rates can also be derived from long time series of radial velocity data (Schmitt et al 2016). The Transiting Exoplanet Survey Satellite (TESS) mission to study exoplanets through photometric transits (Ricker et al 2015), with its nearly full sky coverage, provides, as a bonus, precise photometry of a large sample of eclipsing binary systems with a time baseline of at least A&A proofs: manuscript no.…”

Section: Introductionmentioning

confidence: 99%

Analysis of apsidal motion in eclipsing binaries using TESS data II. A test of internal stellar structure}

Claret,

Giménez,

Baroch

et al. 2021

Preprint

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Context. The measurement of apsidal motion rates in eccentric eclipsing binaries is a unique way to gain insight into the internal structure of stars through the internal density concentration parameter, k 2 . High-quality physical parameters of the stellar components, together with precise measurements of the advance of the periastron, are needed for the comparison with values derived from models. Aims. As a product of the Transiting Exoplanet Survey Satellite (TESS) mission, high-precision light curves of a large number of eclipsing binaries are now available. Using a selection of well-studied, double-lined eccentric eclipsing binary systems, we aim to determine their apsidal motion rates and place constraints on the internal density concentration and compare with the predictions from state-of-the-art theoretical models. Methods. We computed times of minimum light using the TESS light curves of 34 eclipsing binaries with precise absolute parameters. We used the changing difference over time between primary and secondary eclipse timings to determine the apsidal motion rate. To extend the time baseline, we combined the high-precision TESS timings with reliable archival data. On the other hand, for each component of our sample of double-lined eclipsing binaries, we computed grids of evolutionary stellar models for the observed stellar mass exploring ranges of values of the overshooting parameter f ov , the mixing-length parameter, and the metallicity. To find the best solution for the two components we adopted a χ 2 statistic to infer the optimal values of the overshooting parameter and the mixinglength parameter. The theoretical internal structure constants to be compared with the observed values were calculated by integrating the differential equations of Radau for each stellar model. Results. We have determined the apsidal motion rate of 27 double-lined eclipsing binaries with precise physical parameters. The obtained values, corrected for their relativistic contribution, yield precise empirical parameters of the internal stellar density concentration. The comparison of these results with the predictions based on new theoretical models shows very good agreement. Small deviations are identified but remain within the observational uncertainties and the path for a refined comparison is indicated.

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“…Giménez et al 1987;Wolf et al 2006Wolf et al , 2010Kim et al 2018), the change in the shape of the radial velocity curve over time (e.g. Ferrero et al 2013;Schmitt et al 2016;Rauw et al 2016), or the change in the shape of the light curve over time (Bakıs , et al 2008;Harmanec et al 2014;Torres et al 2017). Here we use the equations of Giménez & Bastero (1995) defining the times of eclipse:…”

Section: Apsidal Motion Determinationsmentioning

confidence: 99%

Analysis of apsidal motion in eclipsing binaries using TESS data: I. A test of gravitational theories

Baroch,

Giménez,

Ribas

et al. 2021

Preprint

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Context. The change in the argument of periastron of eclipsing binaries, that is, the apsidal motion caused by classical and relativistic effects, can be measured from variations in the difference between the time of minimum light of the primary and secondary eclipses. Poor apsidal motion rate determinations and large uncertainties in the classical term have hampered previous attempts to determine the general relativistic term with sufficient precision to test general relativity predictions. Aims. As a product of the TESS mission, thousands of high-precision light curves from eclipsing binaries are now available. Using a selection of suitable well-studied eccentric eclipsing binary systems, we aim to determine their apsidal motion rates and place constraints on key gravitational parameters. Methods. We compute the time of minimum light from the TESS light curves of 15 eclipsing binaries with precise absolute parameters and with an expected general relativistic contribution to the total apsidal motion rate of greater than 60%. We use the changing primary and secondary eclipse timing differences over time to compute the apsidal motion rate, when possible, or the difference between the linear periods as computed from primary and secondary eclipses. For a greater time baseline we carefully combine the high-precision TESS timings with archival reliable timings. Results. We determine the apsidal motion rate of 9 eclipsing binaries, 5 of which are reported for the first time. From these, we are able to measure the general relativistic apsidal motion rate of 6 systems with sufficient precision to test general relativity for the first time using this method. This test explores a regime of gravitational forces and potentials that had not been probed before. We find perfect agreement with theoretical predictions, and we are able to set stringent constraints on two parameters of the parametrised post-Newtonian formalism.

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TheαCrB binary system: A new radial velocity curve, apsidal motion, and the alignment of rotation and orbit axes

Cited by 16 publications

References 24 publications

Apsidal motion in the massive binary HD 152218

Apsidal motion in the massive binary HD 152218

Analysis of apsidal motion in eclipsing binaries using TESS data II. A test of internal stellar structure}

Analysis of apsidal motion in eclipsing binaries using TESS data: I. A test of gravitational theories

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