Semidetached Model Research Articles

Cost estimation model using enhance-based differential evolution algorithm

In the present scenario, the cost estimation is one of the challenging problems of software engineering. The problem of cost estimation has increased in the maintenance phase of software development life cycle. This type of problem occurs to solve the optimization algorithm like metaheuristic approach used to reduce the effort and error. This approach is used to reduce the error rate for the initial phase of the software maintenance process. In this paper, new mutation strategies are proposed to improve the convergence rate of differential evolution (DE) algorithm. This algorithm enhances the accuracy of the semidetached model. This model optimizes the parameters using the enhance-based differential evolution algorithm (EABMO). The proposed approach does a better performance of most of the benchmark function (f1–f24). Further, this approach applied the real application of the software industry for reducing the cost estimation and error measurement. The proposed approach minimizes the error comparing performance of semidetached model (project) like magnitude of relative error, mean magnitude relative error and mean squared error. The result verifies that our proposed EABMO algorithm performs better than the semidetached model based DE, GA and PSO algorithm.

CONSTRUCTING SYNCHRONOUSLY ROTATING DOUBLE WHITE DWARF BINARIES

We have developed a self-consistent-field (SCF) technique similar to the one described by Hachisu et al. in 1986 that can be used to construct detailed force-balanced models of synchronously rotating, double white dwarf (DWD) binaries that have a wide range of total masses, mass ratios, and separations. In addition to providing a computational tool that can be used to provide quiet initial starts for dynamical studies of the onset of mass transfer in DWD systems, we show that this SCF technique can be used to construct model sequences that mimic the last portion of the detached inspiral phase of DWD binary evolutions, and semi-detached model sequences that mimic a phase of conservative mass transfer.

Accretion disk in the binary system V367 Cygni

New photoelectric observations of the interacting binary V367 Cyg were made during two consecutive seasons, 1996 and 1997, using the two-channel photometer at Mt. Suhora Observatory. The BVRI light curves are analyzed and system parameters are derived for two alternative models: with and without an accretion disk. A contact conguration is obtained for the no-disk model. The semidetached model, with a disk around the invisible component gives a better t and, in addition, explains most of the observed features of V367 Cyg. The disk in V367 Cyg has a radius of about Rd =2 3R, almost completely lling the secondary component's Roche lobe. Mass is transferred from the less massive (3:3 M) to the more massive (4:0 M) star at a high rate of 5{7 10 5 M/yr.

Eclipsing Binaries in the OGLE Variable Star Catalogs. V. Long-Period EB-Type Light Curve Systems in the Small Magellanic Cloud and the PLC-β Relation

Thirty-eight long-period (P > 10 days) apparently contact binary stars discovered by the OGLE-II project in the SMC show EB-type light curves and an inverted period-color relation with longer orbital periods for redder systems. The strong light variations between eclipses can be explained within a semidetached model in which ellipsoidal variations of a large, evolved, Roche lobe–filling component dominates over eclipse effects in the systemic light changes. The model requires further spectroscopic and color-curve support before it can be fully accepted. It is noted that the dominant role of the Roche lobe–filling component in the total systemic luminosity can explain the new period-luminosity-color (PLC) relation, which has been established for the long-period EB (LP–EB) systems. We call it the PLC-β relation, to distinguish it from the Cepheid relation. Two versions of the PLC-β relation—based on the (B-V)0 or (V-I)0 color indices—have been calibrated for 33 systems with (V-I)0 > 0.25 spanning the orbital period range of 11 to 181 days (it was found that blue systems with (V-I)0 ≤ 0.25 do not follow the same calibration). The relations can provide maximum-light, absolute-magnitude estimates accurate to MV 0.35 mag within the approximate range -3 < MV < +1. In terms of their number in the SMC, the LP–EB binaries are about 50 times less common than the Cepheids. Nevertheless, their large luminosities coupled with continuous light variations make these binaries very easy to spot in nearby galaxies, so that the PLC-β relation can offer an auxiliary and entirely independent method of distance determination to nearby stellar systems rich in massive stars.

Near-Infrared Photometric Studies of R Canis Majoris

We present here the first light curves of the peculiar Algol binary system R Canis Majoris obtained in the near-infrared photometric bands J and K. The light curves are fitted for a semidetached model with the Wilson-Devinney light-curve synthesis program. The parameters of the system are derived. Published light curves in the optical photometric bands (U, Un, B, Bn, V, Vn, Hβw, and Hβn of Guinan, V light curve of Sato, and Hαw and Hαn light curves of Edalati, Khalesse, & Riazi) are reanalyzed and the results are compared. The temperature of the secondary component T2 derived from the light-curve analysis shows an increase toward the near-IR wavelengths, achieving maximum in the K band. The secondary minima are deeper by 0.03 and 0.07 mag and the primary minima are shallower by 0.02 and 0.03 mag in the J and K bands, respectively, than what is expected in these bands from the secondary temperature and primary radius derived from the V band. In the case of the Hα and Hβ light curves, the narrowband light curves yielded higher T2 than the broadband light curves. The values of T2 derived from these bands are found to be higher than those derived from the light curves observed in the neighboring wavelengths. We consider the possibility of the difference in the strength of photospheric absorption of Hα and Hβ lines in the primary and the secondary as a reason for the high values of T2 derived from these light curves. Five epochs of primary minima and four epochs of secondary minima are obtained in the present study. The increased depth of the secondary minima in the near-IR bands compared with the optical bands enabled us to determine the moments of secondary minima with nearly the same accuracy as those of primary minima. All the secondary minima appear at phase 0.5, and the durations are equal for the primary and the secondary eclipses. The epochs of primary minima follow the nearly sinusoidal O-C curve that has been observed for this star in previous studies. The values of O-C for the secondary minima were in the same range as those of the primary minima observed by us. We conclude that the system is in a circular orbit. Our observed epochs of primary minima support the presence of a third component in the system, as proposed by Radhakrishnan, Sarma, & Abhyankar. The effect of the presence of a third, noneclipsing, light source would be to suppress the observed depths of both the eclipses, whereas in this system we find that the secondary eclipse depth is being enhanced and the primary eclipse depth is being suppressed compared with expectations. So we have not fitted for a third light in our light-curve analysis, leaving the nature of the third body, if present, undetermined from our present light-curve analysis. The J-band light curve of R CMa fitted well with a bolometric albedo of the secondary star A2 = 0.5, as expected for a star with a convective atmosphere. But the K-band light curve showed a value of A2 = 0.84. A2 is also found to be higher in the broadband light curves than in the narrowband light curves at all the optical wavelengths (except in the U and Un bands, in which the secondary minima are very shallow). This result can provide clues about the cause of the high A2 observed in many Algol-type binary light curves. A2 is also found to vary for light curves at the same wavelengths but taken at different epochs, which helps us to conclude that the high value of A2 seen in many light curves need not be of photospheric origin.

A photometric and radial velocity study of the double-line eclipsing binary CG virginis

A yellow light curve of this short-period ( P = 0.935298) binary based on 960 photoelectric observations using the 60-cm reflector at Xinglong Station, Beijing Observatory, turned out be of the Algol type. In a first analysis a Russell-Merrill photometric solution and a semidetached model were published in 1978 [5]. 90 normal points were used in computing 10 Wilson-Devinney light curve synthesis solutions in 1982 [7] in which detached models gave smaller residuals than semi-detached ones. The solutions were, however, largely indeterminate, the residuals varying little as the mass-ratio was varied from 0.18 to 7.9. To resolve the indeterminacy of the photometric solution, Lu secured in 1985-86 radial velocity observations at the Dominion Astrophysical Observatory using the 1.8 m telescope, an image tube spectrograph and a Reticon detector. The star was observed to be a two-spectrun binary. A spectroscopic mass ratio of 0.528±0.013 and a spectral type of F7 for the hotter component-dominated blue-violet spectrum enabled yet another Wilson-Devinney photometric solution to be found. The masses are 1.43 ± 0.05 M ⊙ for the F star and 0.76 ± 0.02 M ⊙ for the cooler companion. Some derived estimates are given in TABLE 6. A simplistic comparison with de Jager et al. [9] would classify the stars as around F6 IV and K5 V. Although this binary is a detached system, with Ω inn /Ω 2 = 0.964 , the less massive, cooler component just barely undefills its Roche lobe. And the system shares a number of properties in common with Algol binaries [17–21]. It appears likely that CG Vir may have left the Algol phase not so long ago.

UBV photometric analysis of V758 Centauri

Classical R-M and synthetic W-D analysis of V758 Centauri are presented. Two solutions (semi-detached and contact) were found from differential corrections approach. The semi-detached model is physically acceptable since the system is thermally decoupled. The solution for this case and the photometric data are consistent with a B9 primary and A9 secondary components having parameters close to Main-Sequence values. It is suggested that V758 Centauri is a B-type W UMa system at the brokencontact phase predicted by the Thermal Relaxation Oscillations theory.