The early B-type eclipsing binary GT\,Cephei: a massive triple system?

Abstract

GT\,Cep is a semi-detached close binary system with an orbital period of 4.91 days, containing a massive star. I have obtained spectroscopic observations and derived radial velocities of both components. Combining the analyses of radial velocities and available photometric observations we have measured the absolute parameters of both components of GT\,Cep. The components are shown to be a B2\,V primary with a mass M${}_p$=10.70$\pm$0.50 M${}_{\odot }$ and radius R${}_p$=6.83$\pm$0.19 R${}_{\odot }$ and a A0\,IV secondary with a mass M${}_s$=2.58$\pm$0.14 M${}_{\odot }$ and radius R${}_s$=7.56$\pm$0.21 R${}_{\odot }$. My analyses show that GT\,Cep is a classical Algol-type binary with a less massive secondary filling its $Roche$ lobe. Using the UBVJHK magnitudes and the interstellar reddening of E(B-V)=0.61 I estimated the mean distance to the system as 854$\pm$43\,pc. The O-C residuals have been analyzed as the consequence of a light-time effect superimposed on an upward parabola. My analysis indicates that the eclipsing binary revolves around a third-body with a period of about 57.5 yr in an orbit with a radius of 40 $AU$. The lower limit for the mass of the third star has been estimated to be 7 M${}_{\odot }$ for the inclination between $70^o$ and $90^o$.

29 pages, 5 figures, Accepted by New Astronomy. arXiv admin note: text overlap with arXiv:1406.0334, arXiv:1406.0331

References in corpus (10)

• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• A Computational Guide to Physics of Eclipsing Binaries. Paper I. Demonstrations and Perspectives
• The Indo-U.S. Library of Coude Feed Stellar Spectra
• Northern Sky Variability Survey (NSVS): Public data release
• Coude-feed stellar spectral library - atmospheric parameters
• Absolute dimensions of detached eclipsing binaries. I. The metallic-lined system WW Aurigae
• The most plausible explanation of the cyclical period changes in close binaries: the case of the RS CVn-type binary WW Dra
• Rotational velocities of A-type stars I. Measurement of vsini in the southern hemisphere
• Simulations for Multi-Object Spectrograph Planet Surveys
• V745\,Cassiopeia: an interacting young massive binary in a multiple star system

Cited by in corpus (2)

• Detailed models of interacting short-period massive binary stars
• Determination of the Galactic Rotation Curve from OB Stars