B and V photometry and analysis of the eclipsing binary RZ Cas

Photoelectric light curves of the eclipsing binary RZ Cas are presented forB andV filters. The light curves are analysed for light and geometrical elements, starting with a previously suggested preliminary method. The approximate results thus obtained are then optimised through the Wilson-Devinney computer programs.     

The eclipsing binary WX Eridani

The Algol type eclipsing binary WX Eridani was observed on 21 nights with the 48-inch telescope of the Japal-Rangapur Observatory during 1973–74 and 1974–75 seasons in UBV colors. An improved period ofP=0^d.82327038 was obtained from the analysis of the times of five primary minima. Standstills between phase angles 50–80°, 100–130°, 230–260° and 280–310° were present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with the primary a transit and the secondary an occultation. Elements derived from the solution of the light curve using Russell-Merrill method are given. From the comparison of the fractional radii with Roche lobes, it is concluded that none of the components has filled its respective Roche lobe. The spectral type of the primary component is estimated to be F3 and it is found to be a -scuti type variable pulsating with two periods equal to one-fifth and one-sixth of the orbital period.     

Photo-electric study of the eclipsing binary RU Eridani

B andV observations of the eclipsing binary RU Eridani made on 23 nights during 1974–76 are reported. An improved period of 0^d.63219951 is derived. After rectification ofB andV light curves, new elements are derived using Russel-Merrill method. The system is classified as semidetached.     

BV observations of the eclipsing binary WX Eridani

Photoelectric observations of WX Eridani inB andV filters have been discussed. The maximum magnitudes of the system areB=9 ^m .70 andV=9 ^m .46. TheB-V colours of the components are 0 ^m .16 and 0 ^m .80 for the primary and the secondary, respectively, while their spectral types are A5+K0. The period has been found to be constant and its revised value is 0^d.823 270 76.     

UBV observations of the eclipsing binary FW Monocerotis

Photoelectric observations of FW Monocerotis inU,B, andV filters have been discussed. The depths of the primary minimum inU BV colours are 2 _. ^m 63, 2 _. ^m 17 and 1 _. ^m 76, respectively. No variation in the period has been found and its revised value is 3 _. ^d 8735868.     

UBV photometry of the WR binary CQ Cephei

Photoelectric observations of the WR binary CQ Cephei (WN6+O9) are presented. the depths of the eclipses in the light curves are best represented by an inclination of the orbit i = (68°.8±0.6) and the width of the very asymmetric eclipse curves can be represented by only an overcontact configuration (Ω₁ = Ω₂ = 3.65 ± 0.05, and f = 27%). Simultaneous solution of the light and radial velocity curves strongly supports CQ Cep's membership of the Cep OB1 association. By considering this membership we obtained absolute dimensions of the system, which lead to a consistent physical model for CQ Cephei. The more luminous WR primary turns out to be the hotter but slightly less massive component: M_WR = 20.8 M⊙, R_WR = 8.2R⊙, T_eff(WR) = 43600 K, and M_o = 21.4 M⊙, R_o = 8.3 R⊙, T_eff(O) = 37000 K.     

A photometric study of the short-period eclipsing binary BW Eridani

UBV observations of the short-period eclipsing binary BW Eri are reported and analyzed. The photometric parameters are determined. BW Eri is a detached or semidetached system.     

Photoelectric photometry of the eclipsing binary WX Cancri

We obtained 672 observed points in yellow and 674 in blue in our photoelectric light curve of the Algol-type binary WX Cnc and we give 2 each of the times of primary and secondary minima. Using the Russell-Merrill method, we derived four mutually consistent sets of orbital elements, and determined the spectral type to be F6V for the combined system, and F5V and F8V for the primary and secondary components, separately. We found WX Cnc to be a detached system of two main sequence stars.     

Photoelectric photometry of the eclipsing binary EE Aqr

The system EE Aqr has been observed inUBV colours. A consistent set of orbital elements and a slightly improved period of 0 _. ^d 5089954 have been obtained. The eclipse is partial and variability is of Lyrae-type. The colour of the components has been determined.     

UBV photoelectric observations of the eclipsing binary system XZ Cep

Three color photoelectric observations of the close binary system XZ Cep at the Abastumani Astrophysical Observatory are reported. These data cover the entire light curve and represent, up to now, the best and most extensive observations of this star. The positions of the components of XZ Cep on a mass-log g diagram show that it is in a phase following a rapid transfer of mass. The theoretical light curves are not fully consistent with the observed curves at phases of 0.35-0.40 and 0.6-0.9. This is evidently because of the influence of gaseous flows in the system. The existence of circumstellar matter and gas flows at phases of 0.7-0.9 are also confirmed by spectral data and by changes in the intrinsic polarization of XZ Cep. In addition, a polarimetric study of the star indicates that two or more interstellar clouds with different properties lie between XZ Cep and us. A detailed study of the photoelectric data presented here is also extremely interesting for the confirmation of the latter idea.     

Three-colour photometry of the eclipsing binary EI Cephei

The photoelectric elements of the system EI Cephei have been determined inU, B, V colours. The absolute dimensions have been determined and some evolutionary aspects have been discussed. A modified period of 8^d.439334 has been obtained. The system is a detached one.     

Photographic photometry of the eclipsing binary ad bootes

A detailed two colour (BV) photoelectric photometry of the late-type eclipsing binary AD BOO was carried out in 1981 April–May. We found its period to be 2.0688112 d, double what was thought previously. The light curve outside the eclipses is basically flat with Irregular fluctuations of ˜0.075 mag. It is basically an Algol-type curve, with a principal minimum of 0.65 mag and a secondary minimum of 0.40 mag. The O-C diagram of the minimum epoch shows that the period has tended to increase. The photometric solution by the classical Russel-Merrill method gives k = 0.786. The principal minimum corresponds to a partial eclipse of the transit type.     

DifferentialUBV photometry of the eclipsing binary SVS 2086

PhotoelectricUBV differential observations of the eclipsing binary SVS 2086 are presented. The system shows a W UMa-type light curve, with an amplitude of 0.5 inV light; the period seems to be longer than previously believed.     

Photoelectric photometry of the eclipsing binary V1425 Cygni

Photoelectric differentialB andV magnitudes of the eclipsing binary V1425 Cygni are presented yielding the complete photoelectric light curve of this relatively bright system. The improved light elements are calculated using the least-squares method.     

Photoelectric photometry of eclipsing binary V375 cassiopeiae

Some 604 photoelectric BV observations of the eclipsing binary V375 Cas were obtained at Beijing Observatory from August to November 1982. Photometric solution was carried out using the Wilson-Devinney program for the BV light curves. The system is found to be a semidetached binary in which the less massive component fills its Roche lobe and the more massive component nearly does so. It is very similar to RZ Dra. This very interesting system is important for the understanding of the evolution of close binaries.     

A photometric and spectroscopic study of the short-period eclipsing binary BV Eridani

UBV observations of the short-period eclipsing binary BV Eri are reported and analyzed. The radial velocity curve is given. The system shows a light curve distortion, making an analysis difficult. The secondary fills its critical Roche lobe. The system seems to be in an interesting evolutionary.     

Photoelectric photometry of the RS CVn binary EI Eridani = HD 26337

DifferentialUBV(RI) _KC andUBVRI photometry of the RS CVn binary EI Eridani obtained during December 1987 and January 1988 at fourteen different observatories is presented. A combined visual bandpass light curve, corrected for systematic errors of different observatories, utilizes the photometric period of 1.945 days to produce useful results. Analysis shows the visual light curve to have twin maxima, separated by about 0.4 phase, and a full amplitude of approximately 0.06 mag for the period of observation, a smaller amplitude than reported in the past. The decrease in amplitude may be due to a decrease or homogenization of spot coverage. To fit the asymmetrical light curve, a starspot model would have to employ at least two spotted regions separated in longitude.     

High-speed energy-resolved STJ photometry of the eclipsing binary UZ For

We present high-time-resolution optical photometry of the eclipsing binary UZ For using a superconducting tunnel junction (STJ) device, a photon-counting array detector with intrinsic energy resolution. Three eclipses of the ∼18-mag 126.5-min orbital binary were observed using a 6×6 array of tantalum STJs at the 4.2-m William Herschel Telescope on La Palma. The detector presently provides individual photon arrival-time accuracy to about 5 μs, and a wavelength resolution of about 60 nm at 500 nm, with each array element capable of counting up to ∼5000 photon s⁻¹. The data allow us to place accurate constraints on the accretion geometry from our time- and spectrally resolved monitoring, especially of the eclipse ingress and egress. We find that there are two small accretion regions, located close to the poles of the white dwarf. The positions of these are accurately constrained, and show little movement from eclipse to eclipse, even over a number of years. The colour of the emission from the two regions appears similar, although their X-ray properties are known to be significantly different: we argue that the usual accretion shock may be absent at the non-X-ray-emitting region, and instead the flow here interacts directly with the white dwarf surface; alternatively, a special grazing occultation of this region is required. There is no evidence for any quasi-periodic oscillations on time-scales of the order of seconds, consistent with relatively stable cyclotron cooling in each accretion region.     

UBV photometry of Vesta

A lightcurve of Vesta, obtained on four nights between June 23 and 30 June 1978 during the coordinated campaign for the determination of the rotation period, is presented. The observations were performed at the 91-cm telescope of the Catania Observatory employing UBV filters and a photon counting photometer. The V lightcurve apparently shows a single maximum, suggesting that the 5^h20^m29^s.2 period is the correct one. Features are evident near the maximum and the minimum closely resembling those of Johnson's lightcurve of 22 December 1950 and Taylor's of January 21, 1973. The amplitude in V light is 0^m.105 and small variations are also found in the color indices. The largest color variation is for the U-V with Δm = 0.^m.05, which is slightly larger than the value 0^m.02 found by T. Gehrels [Astron. J.72, 929 (1967)]. The maximum and minimum values occur at the same phase with respect to the maximum V light as found by Gehrels, i.e., Vesta appears bluer near 0^p.25 and redder near 0^p.7. Corrections with the solar phase angle were made using the coefficients given by Gehrels for the B-V and U-V while a new value of 0.036 mag/deg was assumed for the V observations. The available amplitudes of Vesta's lightcurve were analyzed with respect to the longitude position and the solar phase angle.