1SWASP J093010.78+533859.5: A POSSIBLE HIERARCHICAL QUINTUPLE SYSTEM
Jae‐Rim KooJae Woo LeeByeong‐Cheol LeeSeung‐Lee KimChung‐Uk LeeKyeongsoo HongDong-Joo LeeSoo‐Chang Rey
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Among quadruples or higher multiplicity stars, only a few doubly eclipsing binary systems have been discovered. They are important targets for understanding the formation and evolution of multiple stellar systems because we can obtain accurate stellar parameters from photometric and spectroscopic studies. We present the observational results of this kind of rare object, 1SWASP J093010.78+533859.5, for which the doubly eclipsing feature had been detected previously from the SuperWASP photometric archive. Individual point-spread function photometry for two objects with a separation of about 19 was performed for the first time in this study. Our time-series photometric data confirms the finding of Lohr et al. that the bright object A is an Algol-type detached eclipsing binary and the fainter B is a W UMa-type contact eclipsing. Using high-resolution optical spectra, we obtained well-defined radial velocity variations of system A. Furthermore, stationary spectral lines were detected that must have originated from a further, previously unrecognized stellar component. It was confirmed by the third object contribution from the light-curve analysis. No spectral feature of system B was detected, probably due to motion blur by long exposure times. We obtained the binary parameters and the absolute dimensions of systems A and B from light-curve synthesis with and without radial velocities, respectively. The primary and secondary components of system A have a spectral type of K1 and K5 main sequences, respectively. Two components of system B have nearly the same type of K3 main sequence. Light variations for both binaries are satisfactorily modeled by using two-spot models with one starspot on each component. We estimated the distances to systems A and B individually. Two systems may have similar distances of about 70 pc and seem to be gravitationally bound with a separation of about 130 AU. In conclusion, we suggest that 1SWASP J093010.78+533859.5 is a quintuple stellar system with a hierarchical structure of a triple system A(ab)c and a binary system B(ab).Keywords:
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Abstract New BVR light curves and photometric analysis of the eclipsing binary star CN And are presented. The shape of the light curves are typical of β Lyr type, and there are large asymmetries between maxima. The BVR light curves and the radial velocity curves (from Rucinski et al. 2000) were solved with the Wilson‐Devinney method, simultaneously. The results suggest that CN And is a almost contact binary system, in which the component stars are filling ∼99% of their Roche lobes. We discuss the model with a large dark starspot on the more massive star and a bright substellar spot on the companion to account for the light curve asymmetries. The absolute parameters of the system were also derived. The system resembles the near contact binary V1010 Oph according to its Roche configuration and light curve asymmetries. We, also, discuss the evolution of the system: it seems to be in a transition phase to the contact era. All previous times of minimum light were collected and combined with the new ones presented in this work. The variation of the orbital period of the system was then analyzed. The results reveal that the orbital period has a secular decrease of about 1.98 ± 0.04 sec per century, which corresponds to a conservative mass transfer from the more to the less massive component at a rate of (1.52 ± 0.09) × 10 –7 m ⊙ / yr or a mass loss from the primary component due to magnetic stellar winds at a rate of (7.83 ± 0.09) × 10 –8 m ⊙ / yr . (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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Radial velocity measurements and simple sine-curve fits to the orbital velocity variations are presented for the second set of 10 contact binary systems. Eight systems are of the A type: AH Aur, CK Boo, DK Cyg, UZ Leo, XZ Leo, V839 Oph, GR Vir, and NN Vir; V842 Her is the only W type, while SV Equ appears to be a semidetached system seen at a low orbital inclination rather than a contact binary. Several of the studied systems are prime candidates for complete light and radial velocity synthesis solutions.
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Light curves and photometric solutions of the contact binary CE Leo are presented in this paper. The light curves appear to exhibit a typical O'Connell effect, with Maximum I being 0.045 mag (V) and 0.048 mag (B) brighter than Maximum II, respectively, and Maximum I shifting to phase 0.26. The new light curve and those published by Samec et al. (1993) show the change in shape of the light curves of the system. From 1989 to 2001, the difference in the depths between the primary and secondary eclipses increased by 0.100 mag (V) and 0.113 mag (B). The orbital period of the system oscillates with a cycle of about 14 years and a semi-amplitude of 0.004 days. The light curves are analyzed by means of the latest version of the Wilson-Devinney code. The results show that CE Leo is a W-subtype contact binary with a ratio . The asymmetry of the light curves is explained by star spot models. Variations in temperature of the spot on the primary component may be responsible for the light curve variation of the system. The cyclical period change can most probably be attributed to a magnetic activity cycle in the primary component.
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A new light curve of the contact binary FG Hya is presented in this paper. The new light curve and those obtained by other authors from 1955 to 1985 show the change in the shape of the light curves of the system. The difference in the depths between the primary and secondary eclipses increased yearly from 1955 to 1985, but the present light curve seems to exhibit the same shape as the light curve of Smith in 1955. The long-term decrease of the orbital period of the system may be clear if Mahdy et al.'s (1985) timings in question were counted out. The present light curve and those obtained by Binnendijk in 1962 and Yang et al. in 1982 are all analyzed by means of the latest version of the WD program. The results show that FG Hya is an over-contact binary with a small mass ratio. Although the light curves of the system changed considerably, the solutions of the light curves obtained in 1955, 1982 and 1999 are in agreement.
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