Spectroscopic modeling of oscillating Algol-type stars

Tkachenko, A.; Lehmann, H.; Mkrtichian, D. E.

doi:10.1051/0004-6361/200911949

Cited by 25 publications

(40 citation statements)

References 30 publications

(34 reference statements)

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“…The Shellspec program allows the O−C residuals to be inspected for mass-transfer effects like gas streams or an accretion disc, or remnants of past activity like an inhomogeneous distribution of dense circumbinary matter typical for semi-detached (Algol-type) systems. None of these effects could be found here: the two-dimensional (wavelength versus orbital phase) O−C distribution (see Tkachenko et al 2009Tkachenko et al , 2010) is totally flat. Moreover, the almost perfect fit of the line profiles during primary eclipse (Fig.…”

Section: The Roche Geometry Of the Systemmentioning

confidence: 69%

Physical properties of the eclipsingδ Scuti star KIC 10661783

Lehmann

Southworth

Tkachenko

et al. 2013

A&A

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Context. KIC 10661783 is an eclipsing binary that shows δ Scuti-like oscillations. More than 60 pulsation frequencies have been detected in its light curve as observed by the Kepler satellite. Aims. We want to determine the fundamental stellar and system parameters of the eclipsing binary as a precondition for asteroseismic modelling of the pulsating component and to establish whether the star is a semi-detached Algol-type system. Methods. We measured the radial velocities of both components from new high-resolution spectra using TODCOR and compute the orbit using PHOEBE. We used the KOREL program to decompose the observed spectra into its components, and analysed the decomposed spectra to determine the atmospheric parameters. For this, we developed a new computer program for the normalisation of the KOREL output spectra. Fundamental stellar parameters are determined by combining the spectroscopic results with those from the analysis of the Kepler light curve. Results. We obtain T eff , log g, v sin i, and the absolute masses and radii of the components, together with their flux ratio and separation. Whereas the secondary star rotates synchronously with the orbital motion, the primary star rotates subsynchronously by a factor of 0.75. The newly determined mass ratio of 0.0911 is higher than previously thought and means a detached configuration is required to fit the light curve. Conclusions. With its low orbital period and very low mass ratio, the system shows characteristics of the R CMa-type stars but differs from this group by being detached. Its current state is assumed to be that of a detached post-Algol binary system with a pulsating primary component.

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Section: The Roche Geometry Of the Systemmentioning

confidence: 69%

Physical properties of the eclipsingδ Scuti star KIC 10661783

Lehmann

Southworth

Tkachenko

et al. 2013

A&A

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“…This allows the spectroscopic determination of the effective temperatures and of detailed elemental abundances (Hensberge et al 2000;Pavlovski & Hensberge 2005;Frémat et al 2005;Clausen et al 2008;Hareter et al 2008;Pavlovski & Southworth 2009;Tkachenko et al 2009). The effective temperature determined from hydrogen line profiles, and/or from the strength of temperature sensitive lines, supersedes in accuracy and precision those derived from broad-band or Strömgren photometry, for example.…”

Section: Effective Temperaturesmentioning

confidence: 99%

CoRoT 102918586: aγDoradus pulsator in a short-period eccentric eclipsing binary

Maceroni

Montalbán

Gandolfi

et al. 2013

A&A

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Pulsating stars in eclipsing binary systems are powerful tools to test stellar models. Binarity enables us to constrain the pulsating component's physical parameters and this knowledge drastically improves the input physics for asteroseismic studies. The study of stellar oscillations then allows us to improve our understanding of stellar interiors and stellar evolution. The space mission CoRoT discovered several promising objects suitable for these studies. They were photometrically observed with unprecedented accuracy, but needed spectroscopic follow-up. A promising target was the relatively bright eclipsing system CoRoT 102918586, which turned out to be a double-lined spectroscopic binary and also showed clear evidence of γ Dor type pulsations. With the aim of combining the information from binarity and pulsation and fully exploiting the potential of CoRoT photometry we obtained phase resolved high-resolution spectroscopy with the Sandiford spectrograph at the McDonald 2.1m telescope and the FEROS spectrograph at the ESO 2.2 m telescope. Spectroscopy yielded both the radial velocity curves and, after spectra disentangling, the component effective temperatures, metallicity, and line-of-sight projected rotational velocities. The CoRoT light curve was analyzed with an iterative procedure, devised to disentangle eclipses from pulsations. The eclipsing binary light curve analysis, combined with the spectroscopic results, provided an accurate determination of the system parameters, and the comparison with evolutionary models provided strict constraints on the system age. Finally, the residuals obtained after subtraction of the best-fitting eclipsing binary model were analyzed to determine the pulsator properties. We achieved a complete and consistent description of the system. The primary star pulsates with typical γ Dor frequencies and shows a splitting in period that is consistent with high order g-mode pulsations in a star of the corresponding physical parameters. The value of the splitting, in particular, is consistent with pulsations in = 1 modes.

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“…This suggests an absence of a significant amount of gas in the circum-primary space. Similarly, minor phase variations of the strong lines were also found in the semi-detached Algol systems, R CMa (Glazunova et al 2009) and TW Dra (Lehmann et al 2008), and in the quiescent stage of the active Algol-type system, RZ Cas (Tkachenko, Lehmann & Mkrtichian 2009).…”

Section: B E H Av I O U R O F S T Ro N G S P E C T R a L L I N E S O mentioning

confidence: 78%

TX UMa: new orbit, spin rotation and chemical composition of components

Glazunova

Mkrtichian

Rostopchin³

2011

Monthly Notices of the Royal Astronomical Society

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High‐resolution echelle spectra have been obtained of the semi‐detached Algol‐type eclipsing binary system, TX UMa with the high‐resolution echelle spectrographs of the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory in Korea and of the 2.0 m telescope of Peak Terskol Observatory in Russia. New accurate radial velocities of its components have been measured. With the new measurements, we have been able to infer an improved orbital solution and the masses of the components of the system. For the first time, we have measured the rotational velocity for the Roche lobe filling secondary component. We have concluded that it rotates synchronously, while the rotation of the mass‐accreting primary component is 1.5 times faster than synchronous. TX UMa confirms the previous conclusion that the strong lines of the light elements (N, O, Mg) in the atmospheres of mass‐accreting components in Algol‐type systems are stronger and wider than in single stars of the same spectral class and luminosity. Stronger lines also imply higher elemental abundances than weak lines, but this can also be explained if the former have greater microturbulent velocities. We have suggested that such an excess enhancement of the strong lines may be explained in terms of a distended pseudo‐atmosphere of the mass‐accreting component, engendered by gas flowing in via the L1 Lagrange point. We have found the chemical abundances of 12 elements in the atmosphere of the primary component of TX UMa. Si and Ni were found to show significant deficiencies while the abundance measures of C varied (within the uncertainties of the model atmosphere parameters) from solar to noticeably deficient. Other elements, including He, have solar abundance. The abundances of the secondary component are likely solar, as its spectrum is represented well by a synthetic spectrum with solar abundance and Teff= 5500 K and log g = 3.3.

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Spectroscopic modeling of oscillating Algol-type stars

Cited by 25 publications

References 30 publications

Physical properties of the eclipsingδ Scuti star KIC 10661783

Physical properties of the eclipsingδ Scuti star KIC 10661783

CoRoT 102918586: aγDoradus pulsator in a short-period eccentric eclipsing binary

TX UMa: new orbit, spin rotation and chemical composition of components

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