scholarly journals A Study on W Ursae Majoris-Type Systems Recognised by the ROTSE-IIId Experiment

2013 ◽  
Vol 30 ◽  
Author(s):  
D. Çoker ◽  
S. Özdemir ◽  
C. Yeşilyaprak ◽  
S. K. Yerli ◽  
N. Aksaker ◽  
...  
Keyword(s):  
Type Systems ◽  
Light Curves ◽  
Geometrical Parameters ◽  
Mass Ratio ◽  
Orbital Inclination ◽  
Fourier Decomposition ◽  
Search Experiment ◽  
Orbital Periods ◽  
The Fourier Transform ◽  
Optical Transient

AbstractWe present a study on characterising the light curves of W UMa-type systems gathered from the archive containing 5 years of data observed with the Robotic Optical Transient Search Experiment Telescope (ROTSE-IIId) located in Turkey. A sample of 45 W UMa-type systems was studied on the basis of Fourier decomposition of light curves and some basic geometrical parameters, namely degree of contact (f), mass ratio (q), and orbital inclination (i), as approximated values for these systems were determined. Moreover, methods based on the Fourier transform technique were applied to the discrete data to determine the orbital periods of those systems. Preliminary estimates for the system parameters were presented and compared with the values available in the literature.

scholarly journals Period Variation Study and Light Curve Analysis of the Eclipsing Binary GSC 02013-00288

2016 ◽  
Vol 1 (2) ◽  
pp. 321-334 ◽  
Author(s):  
N.S. Awadalla ◽  
M.A. Hanna ◽  
M.N. Ismail ◽  
I.A. Hassan ◽  
M.A. Elkhamisy
Keyword(s):  
Mass Transfer ◽  
Curve Analysis ◽  
Light Curves ◽  
Mass Ratio ◽  
Late Type ◽  
Light Curve Analysis ◽  
Orbital Inclination ◽  
Eclipsing Binary ◽  
Massive Component ◽  
Period Decrease

AbstractWe analyzed the first set of complete CCD light curves of the W UMa type eclipsing binary IK Boo in the BVRI bands by using the PHOEBE code and deduced its first photometric parameters with, mass ratio q = 0.648 and orbital inclination i = 63o. We have applied a spotted model due to the light curves asymmetry. The system shows a distinct O’Connell effect. The best solution fit to the light curves suggested the influence of star spot(s) on both components. Such presence of star spot(s) is common among the RS CVn and W UMa chromospheric active late type stars.We also present an analysis of mid–eclipse time measurements of IK Boo. The analysis indicates a period decrease rate dP/dt = −1.68 × 10−7d/yr, which can be interpreted in terms of mass transfer of rate 3.1 × 10−7M⊙/yr, from the more massive to the less massive component.

scholarly journals W UMa Stars and Angular Momentum Loss

1980 ◽  
Vol 88 ◽  
pp. 491-494 ◽  
Author(s):  
Osmi Vilhu ◽  
Timo Rahunen
Keyword(s):  
Time Scale ◽  
Type Systems ◽  
Light Curves ◽  
Theoretical Studies ◽  
Mass Ratio ◽  
Subsequent Evolution ◽  
Convective Envelope ◽  
Angular Momentum Loss ◽  
Envelope Model ◽  
The Common

The structure and evolution of W UMa stars is still unsolved although considerable progress has been achieved in recent years. Most theoretical studies are based on the common convective envelope model by Lucy (1968a,b), which almost satisfactorily explains the nearly equal minima of the light curves. All A-type (Wilson, 1978) and some W-type systems (Whelan et al., 1979) may contain an evolved primary. In this case stable models exist (Hazlehurst, 1970; Moss and Whelan, 1970). Computations performed for the subsequent evolution (Moss, 1971; Hazlehurst and Meyer-Hofmeister, 1973; Rahunen and Vilhu, 1977) show nuclear time scale evolution towards more extreme mass ratio, supplemented by possible thermal time scale oscillations.

scholarly journals THE CHALLENGES OF MODELLING THE ACTIVITIES OCCURRING ON ECLIPSING BINARIES V1130 CYG AND V461 LYR

2021 ◽  
Vol 57 (2) ◽  
pp. 335-349
Author(s):  
E. Yoldaş ◽  
H. A. Dal
Keyword(s):  
Eclipsing Binaries ◽  
Light Curves ◽  
Secondary Component ◽  
Mass Ratio ◽  
Orbital Inclination ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

We present the findings for the magnetic activities seen on V1130 Cyg and V461 Lyr. In the case of V1130 Cyg, the secondary component's temperature was found to be 3891±50 K, while the mass ratio was computed as 0.689±0.001, and the orbital inclination as 90°.00±0°.01. The temperature of V461 Lyr's secondary component was found to be 4206±50 K, and the mass ratio was calculated as 0.999±0.001 with 89°.58±0°.01 of orbital inclination. The analyses exhibit the effects of the stellar spots on the light curves. The models indicate that there are two types of flares in the case of V1130 Cyg, and three types of flares for V461 Lyr. The Plateau parameters have been found as 2.1997 s for Group 1 and 1.0068 s for Group 2 in the case of V1130 Lyr. They have been computed as 1.9015 s for Group 1, 2.7943 s for Group 2, and 3.4324 s for Group 3 of V461 Lyr.

scholarly journals Light Curve Changes in AH Cancri

2002 ◽  
Vol 187 ◽  
pp. 339-344
Author(s):  
R.M. Branly ◽  
W. Van Hamme
Keyword(s):  
Light Curves ◽  
Mass Ratio ◽  
Third Body ◽  
Remarkable Change ◽  
Ccd Photometry ◽  
Orbital Inclination ◽  
Photometric Observations ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Limb Darkening

AbstractLight curves of the W Ursae Majoris binary AH Cancri obtained in 1973 and 1988 show a remarkable change in shape. Earlier curves have rounded minima and eclipses appear to be partial; later curves have flat-bottomed minima indicating total eclipses. The 1973 curves are consistent with a system in overcontact with an orbital inclination of approximately 65°. Such a low inclination, however, is incompatible with the -duration flat-bottomed eclipse seen in the more recent light curves. Intrigued by this puzzle we decided to make new photometric observations. We present CCD photometry in V and R obtained with the Southeastern Association for Research in Astronomy (SARA) 0.9-m and Buehler Observatory 0.4-m telescopes. We solve the new light curves and find a high-inclination (i ≈ 84°), low-mass-ratio (q ≈ 0.145) model fits the observations reasonably well. In the post-1988 light curves, limb darkening causes eclipses of the cooler star to be deeper than those of the hotter star. Times of minima suggest a possible third body interaction.

scholarly journals New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions

2020 ◽  
Vol 29 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Fatemeh Davoudi ◽  
Atila Poro ◽  
Fahri Alicavus ◽  
Afshin Halavati ◽  
Saeed Doostmohammadi ◽  
...  
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Mass Function ◽  
Light Curves ◽  
Complete Analysis ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Third Body ◽  
Eclipsing Binary

AbstractNew observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m3) = 0.0058 M⊙ in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O’Connell effect was not seen in the light curve and there is no need to add spot.

Preparation and Water Absorbency of Superabsorbent Kaolin/PAA-AM Composite

2013 ◽  
Vol 634-638 ◽  
pp. 1968-1976 ◽  
Author(s):  
Shi Han Shen ◽  
Yu Yu Zhang ◽  
Tian Bin Li ◽  
Qing Le Zeng
Keyword(s):  
Composite Material ◽  
Complex Structure ◽  
Water Absorbency ◽  
Solution Polymerization ◽  
Mass Ratio ◽  
Reaction Conditions ◽  
Superabsorbent Composite ◽  
Optimum Reaction ◽  
The Fourier Transform ◽  
Composite Variables

In this paper, a novel superabsorbent composite material based on acrylic acid (AA), acrylic amide (AM) and inorganic kaolin was synthesized via solution polymerization in aqueous medium with N,N’-methylene bisacrylamide (MBA) as crosslinker and potassium persulfate (KPS) as initiator. The effects of water absorbency of the composite variables, such as neutralization, kaolin concentration and MBA concentration, on the water absorbency were systematically optimized. Evidence of compositing was obtained by a comparison of the Fourier transform infrared spectra of the initial reactants with that of the superabsorbent composites, and its complex structure was confirmed with scanning electron microscope. The water absorbing mechanism was also discussed. The results indicated that the superabsorbent composite material was successfully synthesized and the optimum reaction conditions were as follows: the neutralization degree was 80%, the dosage of kaolin, crosslinker and initiator were 4%, 0.11%, and 0.9% respectively and the mass ratio of AA and AM was 3∶2. The optimum absorbency of the superabsorbent composite material in distilled water could reach 815.6g/g.

scholarly journals γ DOR: A PULSATING COMPONENT OF KIC 8043961 IN A STELLAR TRIPLE SYSTEM

2020 ◽  
Vol 56 (2) ◽  
pp. 179-191
Author(s):  
C. Kamil ◽  
H. A. Dal ◽  
O. Özdarcan ◽  
E. Yoldaş
Keyword(s):  
Major Axis ◽  
Primary Component ◽  
Mass Ratio ◽  
Third Body ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
The Third ◽  
New Findings ◽  
Effective Temperatures ◽  
Orbit Model

We present new findings about KIC 8043961. We find the effective temperatures of the components as 6900 ± 200 K for the primary, and 6598 ± 200 K for the secondary, while the logarithm of the surface gravities are found to be 4.06 cm s-2 and 3.77 cm s-2, respectively. Combination of the light curve with the spectroscopic orbit model results leads to a mass ratio of 1.09 ± 0.07 with an orbital inclination of 73.71 ± 0.14 and a semi-major axis of 8.05 ± 0.22 R⨀ . Masses of the primary and secondary components are calculated as 1.379 ± 0.109 M⨀ and 1.513 ± 0.181 M⨀, while the radii are found to be 1.806 ± 0.084 R⨀ and 2.611 ± 0.059 R⨀. In addition, we obtain a considerable light contribution (≈0.54%) of a third body. We compute a possible mass for the third body as 0.778 ± 0.002 M⨀. We find that the primary component exhibits γ Dor type pulsations with 137 frequencies.

scholarly journals CVs Around the Minimum Orbital Period

2015 ◽  
Vol 2 (1) ◽  
pp. 41-45
Author(s):  
S. Zharikov ◽  
G. Tovmassian
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
Orbital Period ◽  
Cataclysmic Variables ◽  
Outer Edge ◽  
Light Curves ◽  
Mass Ratio ◽  
Period Limit ◽  
Bounce Back ◽  
The Continuum

We discussed features of Cataclysmic Variables at the period minimum. In general, most of them must be WZ Sge-type objects. Main characteristics of the prototype star (WZ Sge) are discussed. A part of WZ Sge-type objects has evolved past the period limit and formed the bounce back systems. We also explore conditions and structure of accretion disks in such systems. We show that the accretion disk in a system with extreme mass ratio grows in size reaching a 2:1 resonance radius and are relatively cool. They also become largely optically thin in the continuum, contributing to the total flux less than the stellar components of the system. In contrast, the viscosity and the temperature in spiral arms formed at the outer edge of the disk are higher and their contribution in continuum plays an increasingly important role. We model such disks and generate light curves which successfully simulate the observed double-humped light curves in the quiescence.

scholarly journals Accurate Fourier Decomposition of Cepheid Radial Velocity Curves

2000 ◽  
Vol 176 ◽  
pp. 233-234 ◽  
Author(s):  
P. Moskalik ◽  
T. Krzyt ◽  
N. A. Gorynya ◽  
N. N. Samus
Keyword(s):  
Radial Velocity ◽  
Light Curves ◽  
Fourier Decomposition ◽  
Hydrodynamical Models ◽  
Classical Cepheid

AbstractThe shapes of light curves and of radial velocity curves are two main predictions of the hydrodynamical models of Cepheids. Of the two, the velocity curves are more robust numerically and therefore, more suitable for comparison with the observations. In this report, we present accurate Fourier parameters for an extensive set of classical Cepheid velocity curves. Published radiative models reproduce the observations very well, with only small discrepancies present. We estimate the center of the ω2 = 2ω0 resonance to occur at Pr = 9.947 ± 0.051 day

scholarly journals The Spotted Contact Binary SS Arietis — Spectroscopy and Infrared Photometry

1992 ◽  
Vol 151 ◽  
pp. 379-382
Author(s):  
P.P. Rainger ◽  
S.A. Bell ◽  
R.W. Hilditch
Keyword(s):  
Imaging Techniques ◽  
Type System ◽  
Light Curves ◽  
Doppler Imaging ◽  
Mass Ratio ◽  
Infrared Photometry ◽  
High Quality ◽  
Precise Location ◽  
Medium Resolution ◽  
Contact Binary

The first infrared photometry for the W-UMa system SS Ari is presented. An analysis based on medium resolution spectroscopy presented here shows that SS Ari is a W-type system with a mass ratio of 0.33. It seems certain that the asymmetry in the published light curves and those obtained for this study can be explained by the effect of spots on one or possibly both components of the system. The precise location, size and temperature of these spots require the use of Doppler Imaging techniques in conjunction with high quality multi-band photometry.

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