Long‐term orbital period behaviors of the neglected Algol type binaries: CC Herculis and XZ Aquilae

Abstract

Orbital period variations of two neglected Algol type binaries, CC Her and XZ Aql, are studied based on all available times of minima. In the case of CC Her, it is found that the O-C curve displays a tilted sinusoidal variation with an eccentricity of 0.54 ± 0.03 and a period of 52.4 ± 0.4 yr, which can be explained by the light-time effect due to the presence of an unseen component. The course of the orbital period change in XZ Aql appears less reliable but its O-C curve can be represented by a periodic variation with a period of 36.7 ± 0.6 yr superimposed on an upward parabola. The parabolic variation indicates a secular period increase with a rate of dP/dt = 7.1 s per century. The corresponding conservative mass transfer from less massive component to the more massive one is about 3.26 × 10 −7 M yr −1 . It is interesting to see that the O-C variation of CC Her displays no evidence (as upward parabola) on the mass transfer characteristic for Algols. The periodic change of the orbital period of XZ Aql, like CC Her, may be caused by the presence of the thirdbody. The lower limits of the masses of the hypothetical unseen components for CC Her and XZ Aql are found to be 2.69 M and 0.47 M , respectively. The third body of CC Her should be detectable not only spectroscopically but also photoelectrically, if it exists.

A new photometric and spectroscopic study of the eclipsing binaries CC Her and CM Lac: physical parameters and evolutionary status

“…Its primary component is a MS star, while the secondary is at the subgiant stage of evolution. The orbital period analysis of the system (Soydugan et al 2006b) did not show evidence of secular change of the period that can be connected with the mass transfer (cf. Hilditch 2001), although the system is semidetached.…”

“…Lanza and Rodonò (2002) and RovithisLivaniou et al (2000) proposed the relations for calculating the Q of a binary's component. Therefore, by substituting to these relations the results of the O−C diagram analysis of Soydugan et al (2006b), and the radius of the secondary component and the system's major axis (see Table 4) we found Q ∼ 7.2 × 10 50 g cm 2 , which lies between the range 10 50 < Q < 10 51 and could potentially implicate the cyclic period modulation of the system (Lanza and Rodonò 2002). Although we found that the secondary component is magnetically active (see Sect.…”

“…Kreiner (1971) noticed for the first time that orbital period changes were occurring in the system, while Soydugan et al (2006b) performed an orbital period analysis and they found that a third body with mass of 2.69 M might orbit the eclipsing pair. Many spectral classifications have been made for the system ranging between A0-A2 spectral types (cf.…”

“…Our results show that the components have masses of 1.91 M and 0.56 M , for primary and secondary, respectively, hence the total mass M 1,2 is 2.47 M . Therefore, according to the results of Soydugan et al (2006b), considering the mass function value (f (m 3 ) = 0.31 M ) and using its formula (cf. Torres et al 2010):…”

Investigation of near-contact semi-detached binary WUMi through observations and evolutionary models

“…The LITE equation as described as a time delay, which is given by Irwin (1959) is commonly used for the analysis of changes in orbital period (e.g. Soydugan et al 2003Soydugan et al , 2006Zasche et al 2014). The parameters derived from the analysis applying the quadratic term and LITE to O-C data are reported in Table 5.…”