An Algol type binary with aδ Scuti component: RZ Cassiopeiae revisited

Abstract

We present new BV photometry and spectroscopic observations of RZ Cassiopeiae. The light and radial velocity curves were formed by the new observations which have been analyzed simultaneously by using the Wilson-Dewinney code. The non-synchronous rotational velocity v1 sin i = 76 ± 6 km s −1 , deduced for the primary component from the new spectroscopic observations, was also incorporated in the analysis. A time-series analysis of the residual light curves revealed the multi-periodic pulsations of the primary component of RZ Cas. The main peak in the frequency spectrum was observed at about 64.197 c d −1 in both B and V bands. The pulsational constant was calculated to be 0.0116 days. This value corresponds to high overtones (n ∼ 6) of non-radial mode oscillations. We find significant changes in the pulsational amplitude of the primary component from year to year. The peak-to-peak pulsational amplitude of the main frequency displays a decrease from 0.m 013 in 2000 to 0. m 002 in 2001 and thereafter we have found an increase again in the amplitude to 0. m 01 in the year 2002. We propose the mass transfer from the cool secondary to the pulsating primary as a possible explanation for such remarkable changes in the pulsational behavior of the primary component.

Spectroscopic modeling of oscillating Algol-type stars

“…This value is clearly higher than the values between 0.331 and 0.338 determined by previous authors. The derived mass of the secondary agrees within the errors of measurement with the values derived by other authors except for Soydugan et al (2006). Thus, the higher value of the mass ratio is caused by the lower value of the mass of the primary of (2.01 ± 0.02) M that we obtained, and the smaller separation of (6.59 ± 0.03) R .…”

“…Thus, the higher value of the mass ratio is caused by the lower value of the mass of the primary of (2.01 ± 0.02) M that we obtained, and the smaller separation of (6.59 ± 0.03) R . The derived radius of the primary of (1.61 ± 0.01) R and the orbital inclination of (82.0 ± 0.3) • agree well with the values derived by Soydugan et al (2006).…”

“…It lists the derived system parameters and compares them with values from literature. The sources are A) Maxted et al (1994), B) Varricatt et al (1998), C) Rodriguez et al (2004), D) Soydugan et al (2006), E) this paper, spectra from 2006. Values that were assumed but not derived by the authors are given in brackets.…”

“…Stellar and system parameters for RZ Cas were derived e.g., by Maxted et al (1994) from combined spectroscopy and UBV photometry (Chambliss 1976), by Varricatt et al (1998) from UBV (Chambliss 1976) and J and K band photometry, by Rodriguez et al (2004) from Stroemgren photometry, by Soydugan et al (2006) from combined spectroscopy and B and V band photometry, and by us (Papers I and II) from spectroscopy. From the color indices, the effective temperature of the primary was derived by Rodriguez et al (2004) to be 8600 K, in agreement with Maxted et al (1994), whereas Varricatt et al (1998) adopted a higher temperature of 8720 K. The mass ratio is given as q = 0.331 by Maxted et al (1994).…”

“…From the color indices, the effective temperature of the primary was derived by Rodriguez et al (2004) to be 8600 K, in agreement with Maxted et al (1994), whereas Varricatt et al (1998) adopted a higher temperature of 8720 K. The mass ratio is given as q = 0.331 by Maxted et al (1994). Soydugan et al (2006) analyzed both the light and radial velocity (RV hereinafter) curves based on photometric observations from 2002 and spectral data from 2003/2004 by using the Wilson-Devinney program (Wilson & Devinney 1971;van Hamme & Wilson 2003). For a fixed surface temperature of the primary of 8600 K, the authors derived the temperature of the secondary to be 4480 K, the mass ratio to be 0.338, the orbital separation to be 6.87 R , and the orbital inclination to be 81.…”