Radial Velocity Studies of Close Binary Stars. X.

Abstract

Radial velocity measurements and sine-curve fits to orbital velocity variations are presented for the ninth set of 10 close binary systems: V395 And, HS Aqr, V449 Aur, FP Boo, SW Lac, KS Peg, IW Per, V592 Per, TU UMi, and FO Vir. The first three are very close, possibly detached, early-type binaries, and all three require further investigation. Particularly interesting is V395 And, whose spectral type is as early as B7/8 for a 0.685 day orbit binary. KS Peg and IW Per are single-line binaries, with the former probably hosting a very low mass star. We have detected a low-mass secondary in an important semidetached system, FO Vir, at q ¼ 0:125 AE 0:005. The contact binary FP Boo is also a very small mass ratio system, q ¼ 0:106 AE 0:005. The other contact binaries in this group are V592 Per, TU UMi, and the wellknown SW Lac. V592 Per and TU UMi have bright tertiary companions; for these binaries, and for V395 And, we used a novel technique of arranging the broadening functions into a two-dimensional image in phase. The case of TU UMi turned out to be intractable even using this approach, and we have not been able to derive a firm radial velocity orbit for this binary. Three systems of this group were observed spectroscopically before: HS Aqr, SW Lac, and KS Peg.

Investigating the surface inhomogeneities of the contact binary SW Lacertae

“…They determined a spectroscopic mass ratio of q sp = 0.776 ± 0.012 and noted that its large uncertainty could be the result of genuine changes in the broadening functions caused by stellar surface activity of the system. By fitting the spectra, Rucinski et al (2005) determined a spectral type of G5V. However, this is hotter than the observed (B−V) value, thus they compromised on a spectral class of G8V.…”

“…The most recent radial velocity study of the system was carried out by Rucinski et al (2005). They determined a spectroscopic mass ratio of q sp = 0.776 ± 0.012 and noted that its large uncertainty could be the result of genuine changes in the broadening functions caused by stellar surface activity of the system.…”

“…LSD requires an input linelist with line profile depths corresponding to the T eff of the system's component stars. There have been several measurements of the spectral type of the system, ranging from G5V to K0V, the most recent being G8V by Rucinski et al (2005). These differences could be a consequence of spot activity.…”

“…Thus, we decided to determine the orbital parameters as a first assumption. We used the values (q, K 1 , V gam ) from Rucinski et al (2005) as the preliminary parameter set, which is compatible with our LSD profiles. The zero-point ephemeris and the orbital period of the system (T 0 , P) were estimated from the 2009 BVR light curves that obtained using the 40 cm Schmidt Cassegrain Kreiken Telescope at the Ankara University Observatory (Şenavcı et al, in prep.).…”

Surface Brightness Variation of the Contact Binary SW Lac: Clues From Doppler Imaging

“…The 2009 and 2010 BV light curves were analysed simultaneously with the radial velocity curves of the system obtained by Rucinski et al (2005) using the interface version of the Wilson-Devinney code (Wilson & Devinney 1971), PHOEBE (Prsa & Zwitter 2005). Since the surface reconstructions of the system were performed using the time series spectra obtained in 2009, we first adopted the spot modeling, as three main circular spot regions, to the 2009 light curves and carried out the LC modeling (see Fig.1).…”