A Photometric Study of the W UMa-type Eclipsing Binary System GSC 0445-1993

Several new light minimum times for the eclipsing binary GSC 0445-1993 have been determined from the observations by Koppelman et al. and the orbital period of this system was revised. A photometric analysis was carried out using the 2003 version of the Wilson-Devinney code. The results reveal that GSC 0445-1993 is a W-type eclipsing binary with a mass ratio of q = 0.323(±0.002) and an over-contact degree of f = 22.8%(±4.2%). A small temperature difference between the components of △T = 135 K and an orbital inclination of i = 65.7°(±0.3°) were obtained. The asymmetry of its light curve (i.e., the O'Connell effect) for this binary star is explained by the presence of a dark spot on the more massive component.     

TZ Lyrae： an Algol-type Eclipsing Binary with Mass Transfer

We present a detailed investigation of the Algol-type binary TZ Lyrae, based on 55 light minimum timings spanning 90 years. It is found that the orbital period shows a long-term increase with a cyclic variation superimposed. The rate of the secular increase is dP/dt = 7.18 × 10?8d yr?1, indicating that a mass transfer from the less massive component to the more massive one at a rate of dm = 2.21 × 10-8M⊙yr-1. The cyclic component, with a period of P3 = 45.5 yr and an amplitude of A = 0d.0040, may be interpreted as either the light-time effect in the presence of a third body or magnetic activity cycles in the components. Using the latest version Wilson-Devinney code, a revised photometric solution was deduced from B and V observations. The results show that TZ Lyr is an Algol-type eclipsing binary with a mass ratio of q = 0.297(±0.003). The semidetached configuration with a lobe-filling secondary suggests a mass transfer from the secondary to the primary, which is in agreement with the long-term period increase of the binary system.     

An Orbital Period Study of the Contact Binary CK Bootis

1　ＩｎｔｒｏｄｕｃｔｉｏｎＣＫＢｏｏｗａｓｄｉｓｃｏｖｅｒｅｄａｎｄｃｏｎｆｉｒｍｅｄｔｏｂｅａｃｏｎｔａｃｔｂｉｎａｒｙｂｙＢｏｎｄ ( 1 975 ) .Ａｆｔｅｒｉｔｓｄｉｓ ｃｏｖｅｒｙｔｈｅｓｙｓｔｅｍｉｓｏｂｓｅｒｖｅｄｆｒｅｑｕｅｎｔｌｙ (ｅ .ｇ .Ａｓｌａｎ ,1 978;ＡｓｌａｎａｎｄＤｅｒｍａｎ ,1 986 :ＰａｊｄｏｓｚａｎｄＺｏｌａ ,1 987;Ｋｒｚｅｓｉｎｓｋｉｅｔａｌ.,1 991ａｎｄＪｉａｅｔａｌ.,1 992 ) .Ａｓｒｅｐｏｒｔｅｄｂｙｓｅｖｅｒａｌａｕｔｈｏｒｓ,ｔｈｅｌｉｇｈｔｃｕｒｖｅｏｆｔｈｅｓｙ…     

Spectroscopic solution of the star QX Cas

High-resolution spectroscopic observations around the Hα line of the binary star QX Cas covering the whole orbital period are presented. Our radial velocity solution, the first ever determined, requires an eccentric orbit with the following orbital parameters: eccentricity,   e = 0.22 ± 0.01  ; longitude of periastron,  ω= 45°± 5°  ; semi-amplitudes of the radial velocity curves of the primary and secondary stars,   K ₁ sin  i = 125.8 ± 0.9 km s⁻¹  and   K ₂ sin  i = 144.8 ± 1.1 km s⁻¹  ; gamma velocity,   V ₀= 65.1 ± 0.5 km s⁻¹  ; and mass ratio,   q = 0.869 ± 0.013  . The corresponding lower limits of the masses of the components and their separation are         , and   a sin  i = 31.34 ± 0.48 R_⊙  .     

First ground‐based photometry and light‐curve analysis of the eccentric eclipsing binary V744 Cas

The first ground‐based BVR photometric observations of the recently discovered eclipsing binary V744 Cas are presented. From these measurements, timings for two primary and one secondary minima have been calculated. The light curves of the system were analyzed by using the Wilson‐Devinney program. The analysis shows that the system is detached with two similar components of spectral type A2V, and the orbit is eccentric (e = 0.0662 ± 0.0005). The longitude of the periastron (ω) was found significantly different for two different light curves (ours and that of Hipparcos), which is strongly suggestive of an apsidal motion with a period of about 425 ± 68 yr. This makes V744 Cas an important candidate for studies of apsidal motions. The first estimate of the absolute dimensions place the system close to the terminal age of the main sequence (TAMS) in the HR diagram. The distance from the spectroscopic parallax (d = 740 ± 10 pc) was found to be slightly larger than the Hipparcos distance of d = 610 ± 400 pc. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

UBVRI Photometry and Polarimetry of the Eclipsing Binary RY Per

Results are presented from multicolor photometric and polarimetric studies of the eclipsing binary RY Per during 2001-2003. Light curves in the UBVRI bands are shown. An analysis of the variations in the linear polarization makes it possible to separate it into interstellar and intrinsic components. The degree of intrinsic polarization of the system away from the eclipse attains a maximum (0.23%) in the B band and falls off rapidly with increasing wavelength. This dependence is indicative of the existence of optically thick gas in the system. An analysis of the polarimetric data also shows that: the total mass of optically thin gas in the system is about 2·10^-10 M , while the total mass of the shell must be several times that; and, the inclination of the orbital plane of the binary system relative to the galactic plane is 4° or 18°.     

The eclipsing binary PV Cas: a case of strong differential rotation in depth

In this study, we show that only models with differential rotation, as opposed to non-rotation or solid-body rotation for the components of PV Cas, are in satisfactory agreement with the observations (including constraints on the apsidal advance rate and the synchronous rotation of the components in addition to their luminosities and radii). Internal rotation profiles found for solar and metal-rich chemical compositions are similar to each other in that only a small part of the outermost regions is rotating very slowly  ( v _eq∼ 65 km s ⁻¹)  and the rest is rotating very rapidly. Confirmation of Ap-like variations in the light curve of the system leads us to search for a connection between this type (and similar types) of internal rotation and chemically peculiar stars. The temperature difference between the blue sides of the main sequence for the normal and for the magnetic Ap stars may arise from such a connection, since we find a similar difference between the models with this kind of rotation and the non-rotating models of somewhat lower mass.     

X1908+075: A Late O-Type Supergiant with a Neutron Star Companion

X1908 + 075 is a highly-absorbed Galactic X-ray source likely made up of a pulsar accreting wind material from a massive companion. We have used near-IR photometric data complemented by follow-up spectroscopy to identify the likely counterpart to this X-ray source and to assign a spectral type O7.5–9.5 If to the primary. Further details can be found in Morel and Grosdidier (2005).     

A multicolor photometric study of the neglected eclipsing binary FT Ursae Majoris

The multicolor photometric observations of the neglected eclipsing binary FT Ursae Majoris (FT UMa) were obtained in 2010. The 2003 version of the Wilson-Devinney code was used to analyze the light curves in the B, V and R bands simultaneously. Based on the spectroscopic mass ratio q = 0.984 published by Pribulla et al., it is found that FT UMa is an evolved contact binary with a contact degree of 15.3%. The low amplitude of light variations, ～ 0.15 mag, arises mainly from a moderately low inclination angle...     

Third Body Problem in the Eclipsing Binary Star TV Cassiopeia

The aim of this work is to search for some evidences for the presence of unseen companion(s) in the eclipsing binary star TV Cassiopeia using its O—C diagram. Assuming that the light-time effect is responsible for the periodic components on the O—C diagram, the set of orbital parameters were derived using Irwin's (1959) method. The resulting orbital parameters and mass of the hypothetical third body are physically acceptable. Lacking other proofs of the third body presence, however, the hypothesis can be treated as a probable case only.This revised version was published online in October 2005 with corrections to the Cover Date.     

GSC3658-0076: A Binary System at the Beginning of Mass Transfer

Photometric data of the new discovered binary GSC3658-0076 observed by [González-Rojas et al.: 2003, IBVS, No. 5437.] were analyzed using the latest Wilson-Devinney code. The system turns out to be a detached binary system with the primary component almost filling its Roche lobe, while the secondary one is detached from the critical Roche lobe. According to the mass-radius relation of unevolved (ZAMS) detached binaries given by [Demircan and Kahraman: 1991, Ap&SS 181, 313.], the primary component is more evolved. These properties reveal that GSC3658-0076 may be at the beginning of the mass transfer phase and may evolve from the present detached system into a contact binary or be in the broken-contact phase predicted by TRO theory.     

Photometric Observations and Light Curve Studies of the Semi-Detached Eclipsing Binary R CMa

We present observations and light curve analysis of the eclipsing binary R CMa in the narrow band filters v and b. Observations were made during 1993 at Biruni Observatory and the light curves have been analyzed using the Wilson-Devinney light curve interpretation program. Assuming a semi-detached configuration for R CMa, the parameters i, Ω₁, L ₁, T ₂ and A ₂ were adjusted for the best fit between the synthesized light curves and observations. Both light curves were fitted well with a lower value of bolometric albedo than what would be expected for a normal cool star with a convective envelope. The masses of the primary and secondary components and the absolute dimensions of the stars have been calculated using the derived relative dimensions from Wilson-Devinney codes and the spectroscopic observations.     

Velocity curve analysis of the spectroscopic binary stars RZ Cas,CC Cas,HS Her,HD 93917, V921 Her and Y Cygni by the artificial neural networks

We use an Artificial Neural Network (ANN) to derive the orbital parameters ofspectroscopic binary stars. Using measured radial velocity data of six double‐lined spectroscopic binary systems RZ Cas, CC Cas, HS Her, HD 93917, V921 Her and Y Cygni, we find corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with those obtained by others using more traditional methods (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A long trail behind the planetary nebula HFG1 (PK 136+05) and its pre-cataclysmic binary central star V664 Cas

A deep wide-field image in the light of the Hα and [N  ii ] 6548 & 6584 Å emission lines, of the planetary nebula HFG1 which surrounds the pre-cataclysmic binary system V664 Cas, has revealed a tail of emission at least 20 arcmin long, at a position angle of 316°. Evidence is presented which suggests that this is an  ≈10⁵ yr  old trail of shocked material, left behind V664 Cas as it ejects matter whilst ploughing through its local interstellar media at anywhere between 29 and 59 km s⁻¹ depending on its distance from the Sun.     

AD Cancri：A Contact Binary with Components in Poor Thermal Contact

We present the light curve and photometric solutions of the contact binary AD Cnc. The light curve appears to exhibit a typical O'Connell effect, with Maximum I brighter than Maximum II by 0.010 mag. in V. From 1987 to 2000, the light curve showed changes of shape: the depth of the primary eclipse increased by about 0.056m while that of the secondary eclipse decreased by about 0.032m, so the difference between the primary and the secondary eclipses increased by about 0.088m, while there was no obvious variation in the O'Connell effect. Using the present and past times of minimum light, the changes in the orbital period of the system are analyzed. The result reveals that the orbital period of AD Cnc has continuously increased at a rate of dp/dt = 4.4 ×10-7day yr-1. The light curve is analyzed by means of the latest version of the Wilson-Devinney code. The results show that AD Cnc is a W-subtype contact binary with a small mass ratio of 0.267 and the two components are in poor thermal contact. AD Cnc has     

A Library of Eclipsing Binary Light-Curves: Fast Initial Parameters Estimation, and on the Uniqueness of the Inverse Problem

In order to improve the light curve solutions we suggest to use a new approach. A library of the Fourier-coefficients (up to 20th term) of (several millions of) light curves was constructed each of the light curves has different input parameters. A light curve solution is made in a very fast way: its discrete Fourier-transform yields not more than some simple number which are compared to the Fourier-coefficients in the library. A chi-squared test can help us to estimate very good initial parameters for the differential correction analysis. The library can also be used to study the uniqeness problem of the light curve solutions. Here we investigated the uniqueness of the spot solution of SV Cam.