Triple systems showing apsidal motion

Bozkurt, Z.; Değirmenci, Ö. L.

doi:10.1111/j.1365-2966.2007.11971.x

Cited by 29 publications

(16 citation statements)

References 55 publications

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“…Wolf et al (1996) adopted e = 0.14 and foundω obs = 0.183 ± 0.026 • yr −1 , whereas Kozyreva & Khaliullin (1999) assumed e = 0.17 to obtainω obs = 0.149 ± 0.015 • yr −1 . Finally, Bozkurt & Degirmenci (2007) arrived at e = 0.1018 ± 0.0006 andω obs = 0.486 ± 0.004 • yr −1 . Thiṡ ω obs is consistent withω GR +ω cl , although its errorbar is certainly too small.…”

Section: Apsidal Motionmentioning

confidence: 95%

“…These shorter apsidal periods are closer to theoretical expectations, but the low e conflicts with other observations (Hilditch 1972b;Maloney et al 1991). In addi-1 Department of Physics, Faculty of Sciences, University of Zagreb, Zagreb, Croatia 2 Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK tion, a third body has been found orbiting AS Cam with a period of P 3 = 2.2 yr (Kozyreva & Khaliullin 1999;Bozkurt & Degirmenci 2007), albeit with a low statistical significance.…”

Section: Introductionmentioning

confidence: 99%

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Apsidal Motion of the Eclipsing Binary as Camelopardalis: Discrepancy Resolved

Pavlovski

Southworth

Kolbas

2011

ApJ

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We present a spectroscopic study of the eclipsing binary system AS Camelopardalis, the first such study based on phase-resolved CCDéchelle spectra. Via a spectral disentangling analysis we measure the minimum masses of the stars to be M A sin 3 i = 3.213±0.007 M ⊙ and M B sin 3 i = 2.323±0.006 M ⊙ , their effective temperatures to be T eff (A) = 12 840 ± 120 K and T eff (B) = 10 580 ± 240 K, and their projected rotational velocities to be v A sin i A = 14.5 ± 0.1 km s −1 and v B sin i B 4.6 ± 0.1 km s −1 . These projected rotational velocities appear to be much lower than the synchronous values. We show that measurements of the apsidal motion of the system suffer from a degeneracy between orbital eccentricity and apsidal motion rate. We use our spectroscopically-measured e = 0.164±0.001 to break this degeneracy and measureω obs = 0.133 ± 0.010 • yr −1 . Subtracting the relativistic contribution oḟ ω GR = 0.0963 ± 0.0002 • yr −1 yields the contribution due to tidal torques:ω cl = 0.037 ± 0.010 • yr −1 . This value is much smaller than the rate predicted by stellar theory, 0.40-0.87 • yr −1 . We interpret this as a misalignment between the orbital axis of the close binary and the rotational axes of its component stars, which also explains their apparently low rotational velocities. The observed and predicted apsidal motion rates could be brought into agreement if the stars were rotating three times faster than synchronous about axes perpendicular to the orbital axis. Measurement of the Rossiter-McLaughlin effect can be used to confirm this interpretation.

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Section: Apsidal Motionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Apsidal Motion of the Eclipsing Binary as Camelopardalis: Discrepancy Resolved

Pavlovski

Southworth

Kolbas

2011

ApJ

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“…We still know only a few such systems nowadays, see e.g. Bozkurt & Deǧirmenci (2007), while HV 2274 is the first to be discovered out of our Galaxy. Only precise spectral observations and their disentangling should reveal its true nature.…”

Section: Discussionmentioning

confidence: 99%

Apsidal motion and absolute parameters for five LMC eccentric eclipsing binaries

Zasche

Wolf

2013

A&A

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Aims. As part of our observational projects at the La Silla Danish 1.54-meter telescope, we aim to measure the precise times of minimum light for eccentric eclipsing binaries in the Large Magellanic Cloud, needed for accurate determination of apsidal motion. Many new times of minima were derived from the photometric databases OGLE and MACHO. Several new minima were also observed. Methods. The O-C diagrams of the systems were analysed using all reliable timings found in the literature, and new or improved elements of apsidal motion were obtained. Light and radial velocity curves of MACHO 81.8881.47 and MACHO 79.5377.76 were analysed using the program PHOEBE. Results. We derived for the first time or significantly improved the relatively short periods of apsidal motion of 211 (12), 127 (8), 48 (13), 103 (20), and 42 (19) years, respectively. The internal structure constants, log k 2 , were found to be -2.37, -2.47, -2.17, -2.02, and -1.86 respectively, under the assumption that the component stars rotate pseudosynchronously. The relativistic effects are weak, up to 6% of the total apsidal motion rate. The masses for MACHO 81.8881.47 resulted in 5.51 (0.21) and 5.40 (0.19) M , while for MACHO 79.5377.76 the masses are 11.26 (0.35) and 11.27 (0.35) M , respectively.

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“…To determine the number of ionizing photons (log Q 0 ) for O-type stars, we used Martins et al (2005). For B0 V stars, we used the values given by Simón-Díaz & Stasińska (2008) and for the B0.5−B1 V spectral types we took the radii from the binary CW Cep (Bozkurt & Degirmenci 2007), the spectral type−T eff relation from Lefever et al (2010), and the T eff − log q 0 from the B-star grid from Lanz & Hubeny (2007).…”

Section: Ionizing Sourcesmentioning

confidence: 99%

Near-infrared study of the stellar population of Sh2-152

Alegría

Herrero

Marín-Franch

et al. 2011

A&A

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Context. The discovery of new massive star clusters and massive stellar populations in previously known clusters in our Galaxy by means of infrared studies has changed our view of the Milky Way from an inactive to an active star-forming machine. Within this scenario, we present a near-infrared spectrophotometric study of the stellar content of the compact HII region Sh2-152. Aims. We aim to determine the distance, extinction, age, and mass of Sh2-152, using for the first time near-infrared stellar classification for several sources in the region. Methods. Using our near-infrared (J, H, and K S ) photometry and the colour-magnitude diagram for the cluster field, we selected 13 bright stars, candidate members of the reddened cluster's main sequence, for H-and K-spectroscopy and spectral classification. This near-infrared information was complemented with an optical spectrum of the ionizing central star to confirm its spectral nature. Results. From the 13 spectroscopically observed stars, 5 were classified as B-type, 3 as G-type, 2 were young stellar objects (YSOs), and 3 remained unclassified (because of the poor data quality). The cluster's extinction varies from A K S = 0.5 to 2.6 mag (A V = 4.5 to 24 mag) and the distance is estimated to be 3.21 ± 0.21 kpc. The age of the cluster is younger than 9.4 Myr and the lower limit to the total mass of the cluster is (2.45 ± 0.79) × 10 3 M . We compare the number of ionizing photons emitted from the OB-type stars with the Lyman continuum photons derived from the radio observations and conclude that both quantities are consistent for the central region of Sh2-152. In contrast, the main ionizing source of the lower region remains unidentified.

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Triple systems showing apsidal motion

Cited by 29 publications

References 55 publications

Apsidal Motion of the Eclipsing Binary as Camelopardalis: Discrepancy Resolved

Apsidal Motion of the Eclipsing Binary as Camelopardalis: Discrepancy Resolved

Apsidal motion and absolute parameters for five LMC eccentric eclipsing binaries

Near-infrared study of the stellar population of Sh2-152

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