A new photometric study of CW Cephei and its apsidal motion

Abstract

Abstract. New photoelectric observations of the eccentric orbit binary CW Cephei have been carried out in B, V and R colours during the 2000 observing season at TÜBITAK (The Scientific and Technical Research Council of Turkey) National Observatory. The light curves of the system were analyzed with a nonsynchronous rotation approach using the method of Wilson-Devinney in B, V and R bands, simultaneously. Especially, we used the R band to check for a third light in the solution as distinct from previous studies. But, the third light contribution in the light curves comes out to be almost negligible. In this study, the values of the longitude of periastron (ω) of the system's orbit found in the solutions of the light curves and radial velocity curves were collected and the variation of ω with time was investigated. A new value of the apsidal motion velocity has been obtained asω=0.0582 ± 0.0011 (deg/cycle), corresponding to an apsidal period U=46 ± 1 yr.

Apsidal motion in eccentric eclipsing binaries: CW Cephei, V478 Cygni, AG Persei, and IQ Persei

“…Such a component of a spectral type K5 with bolometric magnitude m 3 = 6.8 mag produces the third light of L 3 = 0.0005% only, which is still in contradiction with the contribution of the third light of about 3-5% given in Han et al (2002) or about 1% derived by Erdem et al (2004).…”

“…A detailed study of the apsidal motion of CW Cep was recently carried out by Erdem et al (2004), but we decided to perform a re-analysis in light of the new times of minima now available. Besides those given in Table 1, we have added the times of minimum obtained by Han et al (2002, their Table 1), Agerer & Hübscher (2003), Hübscher (2005), and Hübscher et al (2005).…”

Modelling of the B-type binaries CW Cephei and U Ophiuchi

“…This problem has been extensively discussed by Clausen & Gimenez (1991), who found that the spread in radii ratios is also accompanied by a significant spread in the sum of the radii. Subsequent analysis of their own new photometry by Han et al (2002) and Erdem et al (2004) did not settle issue as they used a different methodology from Clausen & Gimenez (1991). Specifically, Han et al (2002) did not prefer the photographically determined light ratio over that returned from the light curve modelling, and Erdem et al (2004) allowed for the possibility of asynchronous rotation in the components, which alters the light ratios derived from photometric modelling.…”

“…Subsequent analysis of their own new photometry by Han et al (2002) and Erdem et al (2004) did not settle issue as they used a different methodology from Clausen & Gimenez (1991). Specifically, Han et al (2002) did not prefer the photographically determined light ratio over that returned from the light curve modelling, and Erdem et al (2004) allowed for the possibility of asynchronous rotation in the components, which alters the light ratios derived from photometric modelling. Comparing the radii derived by different previous analyses (a complete set of the references are given in Han et al 2002), a spread of ∼8% is found.…”

Triple systems showing apsidal motion

“… *(1) Kozyreva, Kusakin & Khaliullin (2005), (2) Wolf & Zejda (2005), (3) Bozkurt (2000), (4) Kozyreva et al (1999), (5) Erdem et al (2004), (6) Wolf et al (2006), (7) Wolf, Diethelm & Hornoch (2001), (8) Değirmenci et al (2003), (9) Wolf et al (2002), (10) Khaliullin & Khaliullina (2002), (11) Wolf et al (1999), (12) Bozkurt & Değirmenci (2002), (13) Alencar et al (1997), (14) Wolf (2000), (15) González et al (2005), (16) Wolf, Diethelm & Zejda (2005) and (17) Bozkurt (2006). …”