Asiago eclipsing binaries program^*,**

II. V505 Persei

¹ INAF – Osservatorio Astronomico di Padova, Sede di Asiago, 36012 Asiago (VI), Italy e-mail: lina.tomasella@oapd.inaf.it
² INAF – Osservatorio Astronomico di Collurania, Via M. Maggini, 64100 Teramo, Italy
³ via Filzi 9, 38034 Cembra (TN), Italy
⁴ University of Ljubljana, Department of Physics, Jadranska 19, 1000 Ljubljana, Slovenia

Received: 31 July 2007
Accepted: 30 November 2007

Abstract

The orbit and fundamental physical parameters of the double-lined eclipsing binary V505 Per are derived by means of Echelle high-resolution and high spectroscopy, and B, V photometry. In addition, effective temperatures, gravities, rotational velocities, and metallicities of both components are also obtained from atmospheric analysis, showing an excellent match with the results of the orbital solution. An E_B-V ≤ 0.01 mag upper limit to the reddening is derived from intensity analysis of interstellar NaI (5890.0 & 5895.9 Å) and KI (7699.0 Å) lines. The distance to the system computed from orbital parameters (60.6 ± 1 pc) is identical to the newly re-reduced Hipparcos parallax (61.5 ± 1.9 pc). The masses of the two components (M₁ = 1.2693±0.0011 and M₂ = 1.2514±0.0012 ) place them in the transition region between convective and radiative stellar cores of the HR diagram, with the more massive of the two already showing the effect of evolution within the main sequence band (T₁ = 6512±21 K, T₂ = 6462±12 K, R₁ = 1.287±0.014, R₂ = 1.266±0.013 ). This makes this system particularly relevant to theoretical stellar models as a test of the overshooting. We compare the firm observational results for V505 Per component stars with the predictions of various libraries of theoretical stellar models (BaSTI, Padova, Granada, Yonsei-Yale, Victoria-Regina), as well as with BaSTI models computed specifically for the masses and chemical abundances of V505 Per. We find that the overshooting at the masses of V505 Per component stars is already pretty low, but not nil, and it is described by efficiencies = 0.093 and 0.087 for the 1.27 and 1.25  components, respectively. According to the computed BaSTI models, the age of the system is ~0.9 Gyr, and the element diffusion during this time has reduced the surface metallicity from the initial [M/H]= -0.03 to the current [M/H] = -0.13, in excellent agreement with the observed [M/H] = -0.12±0.03.