The first high-amplitude   Scuti star in an eclipsing binary system

Abstract

We report the discovery of the first high-amplitude δ Scuti star in an eclipsing binary, which we have designated UNSW-V-500. The system is an Algol-type semi-detached eclipsing binary of maximum brightness V = 12.52 mag. A best-fitting solution to the binary light curve and two radial velocity curves is derived using the Wilson-Devinney code. We identify a late-A spectral-type primary component of mass 1.49 ± 0.02 M and a late-K spectral-type secondary of mass 0.33 ± 0.02 M , with an inclination of 86.• 5 ± 1.• 0, and a period of 5.350 4751 ± 0.000 0006 d. A Fourier analysis of the residuals from this solution is performed using PERIOD04 to investigate the δ Scuti pulsations. We detect a single pulsation frequency of f 1 = 13.621 ± 0.015 cd −1 , and it appears that this is the first overtone radial mode frequency. This system provides the first opportunity to measure the dynamical mass for a star of this variable type; previously, masses have been derived from stellar evolution and pulsation models.

Determination of tidal distortion in the eclipsing binary system V621 Cen by means of deviations from the third Kepler law

“…It maybe interesting to note that for the (detached, R/a ∼ 0.1) eclipsing binary system with circular orbit WW Aurigae (Southworth et al, 2005) the discrepancy between P Kep , computed as here for V621 Cen, and P b is well compatible with zero being (P Kep /P b ) 2 − 1 = (0.09 ± 5.18) × 10 −3 ; the tidal components of the orbital period are of the order of 10 −4 d for both stars, while the uncertainty in the Keplerian one is about one order of magnitude larger. The same holds for the (semi-detached, R m /a = 0.25) eclipsing binary UNSW-V-500 (Christiansen et al, 2007) for which (P Kep /P b ) 2 − 1 = (0.3±5)×10 −2 ; in this case the tidal distortion of m affects the orbital period at 10 −2 d level, while the bias due to the Keplerian component amounts to 10 −1 d.…”

Asteroseismology of Eclipsing Binary Stars

“…Classical pulsations in A and F stars have been successfully detected using groundbased observations in a few dozen detached and semi-detached eclipsing binary sys-tems (see, e.g., Mkrtichian et al, 2004;Rodríguez and Breger, 2001, and references therein). However, the short time base and precision of ground-based photometry often limited the number of reliable pulsation frequencies that were detected, and only for a small number of these systems full dynamical orbits could be combined with a secure detection of high-amplitude pulsations (see, e.g., Christiansen et al, 2007).…”

Binarity and multiperiodicity in high-amplitude δ Scuti stars

“…Kim et al 2003; Mkrtichian et al 2006; Soydugan et al 2006; Christiansen et al 2007; Pigulski & Michalska 2007). Currently, we know about 40 such δ Scutis, of which only one belongs to the HADS group (Christiansen et al 2007). There are also a handful of non‐eclipsing binary HADS (Rodríguez & Breger 2001), usually deduced from the apparent cyclic period changes but with a few exceptions, like the single‐lined spectroscopic binary SZ Lyn.…”

“…There has been a great interest recently in δ Scuti stars that reside in eclipsing binary systems (e.g. Kim et al 2003; Mkrtichian et al 2006; Soydugan et al 2006; Christiansen et al 2007; Pigulski & Michalska 2007). Currently, we know about 40 such δ Scutis, of which only one belongs to the HADS group (Christiansen et al 2007).…”