1SWASP J024148.62+372848.3: A spotted overcontact binary system under the short-period limit

With the 2013 version of W-D code, we derived the photometric solutions for the new discovered extremely short-period eclipsing binary 1SWASP J024148.62+372848.3 based on its complete RI_c light curves. The results show that the system is a W-type overcontact system with a filling-out factor of 23% and a mass ratio of q = 1.23, thus it is a new target which belongs to the rare group of overcontact binary with period under the short period limit (0.22 days). The obviously asymmetries found in its light curves could be explained well by the high spots coverage on the two components which have strong magnetic activities due to their late type nature. A third light contributing about 40% of the total light has been detected during the light curve analysis. This additional component may play an important role in the formation of 1SWASP J024148.62+372848.3, just like those in other overcontact binaries below the limit.     

A photometric study of the short-period eclipsing binary 1SWASP J204932.94-654025.8, showing strong third light

1SWASP J204932.94-654025.8 (hereafter J2049) is a newly discovered eclipsing binary system with an orbital period of 0.2299103 days. BVR_c light curves (LCs) are presented and analyzed by using the 2013 version of the Wilson–Devinney (W–D) program. Because the observed LCs are asymmetric, a hot star-spot was employed on the secondary component during our analysis. We found that J2049 is a W-subtype shallow contact eclipsing binary system with an orbit inclination of 62^∘.69 ± 0^∘.95 and a mass ratio of q =1.326 ± 0.056. More importantly, we found the presence of a strong third light, with an average luminosity contribution of 31.3% of the total light. Based on times of the light minima, the orbital period changes of J2049 are studied for the first time, and there is no evidence for any significant dp/dt now. Considering the presence of the third light and the short time span of the eclipse times, more observations are needed in the future.     

Orbital solution and evolutionary state for the eclipsing binary 1SWASP J080150.03+471433.8

We present an orbital solution study for the newly discovered system 1SWASP J080150.03+471433.8 by means of new CCD observations in VRI bands. Our observations were carried out on 25 Feb. 2013 using the Kottamia optical telescope at NRIAG, Egypt. 12. New times of minima were estimated and the observed light curves were analysed using the Wilson–Devinney code. The accepted orbital solution reveals that the primary component of is more massive and hotter than the secondary one by about 30 K. The system is an over-contact one with fillout ratio ∼29% and is located at a distance of about 195 Pc. The evolutionary status of the system is investigated by means of stellar models and empirical data.     

NSVS 01286630:a detached binary with a close-in companion

New photometric observations of NS VS 01286630 were performed and two sets of fourcolor(B, V, R_c, I_c) light curves(LCs) were obtained. Using the 2013 version of the Wilson-Devinney(W-D) code, we analyzed these data. The photometric solutions reveal that NS VS 01286630 is an active detached eclipsing binary(EB) with a high orbital inclination(nearly 90°). Remarkably, the temperature of the primary component(the hotter star) is higher than the secondary one, but the value of mass ratio q(M2/M1)for NS VS 0128663 is more than 1, which can be explained in that the surface of the secondary component of NSVS 01286630 is covered with big cool starspots. Based on our new CCD mid-eclipse times and the data published until now, variations in the mid-eclipse times were reanalyzed in detail using a weighted least-squares method. It is discovered that the(O-C) diagram of the system shows a cyclic oscillation with a period of 3.61 yr and an amplitude of 0.001 d. The cyclic variation may be caused by the light-travel time effect(LTTE) due to the presence of a third companion, whose mass we calculated as M3 sin(i_3) =0.11 M(?). The third body may affect the orbital evolution of the central binary system by transferring angular momentum.     

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33+114639.1(hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney(W-D) code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the(O-C) method,the variation of orbital period is studied using all the available times of minimum light. The(O-C) diagram reveals that the period is increasing continuously at a rate of d P/dt = +2.09×10~(-7) d yr~(-1),which can be explained by mass transfer from the less massive component to the more massive one.     

Two-Micron All-Sky Survey J01542930+0053266: a new eclipsing M dwarf binary system

We report on Two-Micron All-Sky Survey (2MASS) J01542930+0053266, a faint eclipsing system composed of two M dwarfs. The variability of this system was originally discovered during a pilot study of the 2MASS Calibration Point Source Working Data base. Additional photometry from the Sloan Digital Sky Survey yields an eight-passband light curve from which we derive an orbital period of  2.639 0157 ± 0.000 0016  d. Spectroscopic followup confirms our photometric classification of the system, which is likely composed of M0 and M1 dwarfs. Radial velocity measurements allow us to derive the masses  (M₁= 0.66 ± 0.03 M_⊙; M₂= 0.62 ± 0.03 M_⊙)  and radii  (R₁= 0.64 ± 0.08 R_⊙; R₂= 0.61 ± 0.09 R_⊙)  of the components, which are consistent with empirical mass–radius relationships for low-mass stars in binary systems. We perform Monte Carlo simulations of the light curves which allow us to uncover complicated degeneracies between the system parameters. Both stars show evidence of Hα emission, something not common in early-type M dwarfs. This suggests that binarity may influence the magnetic activity properties of low-mass stars; activity in the binary may persist long after the dynamos in their isolated counterparts have decayed, yielding a new potential foreground of flaring activity for next generation variability surveys.     

Photometric study of the newly discovered short period eclipsing binary 1SWASP J133105.91 + 121538.0

A total of 311 BVRI observations were carried out on 4 May 2013 for the new short period W UMa system 1SWASP J133105.91 + 121538.0 using the 1.88 m reflector telescope of Kottamia Astronomical Observatory (KAO) at NRIAG. A photometric solution of these light curves was obtained by means of Wilson–Devinney (WD) code. A spotted model was applied to treat the asymmetry of the light curve. The results show that the more massive component is hotter than the less massive one with about ΔT ∼ 300 K. The system is at a distance of 89 ± 3.6 pc. Based on the physical parameters of the system, we investigate the evolutionary state of the components. Both components are above the zero age main sequence (ZAMS) track by about 0.2 magnitudes.     

The eccentric orbit of the short-period eclipsing binary V 1010 Oph

Radial velocity observations of V 1010 Oph obtained at Asiago from 23 spectra combined with those published by Guinan and Koch (1977) reveal a significant eccentricity (e0.20±0.03) with a periastron angle close to 90° at 1 level. This underlines the need for a new analysis of the light curve for photometric elements.On leave from Konkoly Observatory, Budapest, Hungary     

The multi-band CCD photometric investigation of short-period eclipsing binary V1044 Her

We present new CCD photometric observations of V1044 Her obtained on May 22, 23 and 24, 2015. From our data, we derived five new light curve minimum times. Combining our new results with previously available CCD light minimum times, we derived an updated ephemeris and discovered that the period of this binary system exhibits an oscillation. The cyclic variation may be caused by the light-time effect via the presence of a third body or magnetic activity cycle. We calculated the corresponding period of the third body to be 14.1 ± 1.4 years or magnetic cycle to be 12.2 ± 0.7 years. We analyzed our new asymmetric light curves to obtain photometric solutions and starspot parameters using the Wilson and Devinney program. The final results show that V1044 Her is a contact binary system with a degree of contact factor f = 3.220( ± 0.002)%.     

1SWASP J010313.78+352903.7: A Totally Eclipsing Binary with Components in Poor Thermal Contact

We presented photometry for an EB-type totally eclipsing binary, 1SWASP J010313.78+352903.7, observed with the Xinglong 85 cm telescope on 2021 October 22. Light curves in five bands(including the TESS data) were analyzed by employing the Wilson–Devinney method. The photometric solutions show that it is a contact binary with a relatively low mass ratio(q ≌ 0.28), relatively large fill-out factor( f ≌ 40%) and large temperature difference(Δ T ≌ 1700 K). Max.I-Max.II is up to about 9% of variable ...     

The eclipsing binary system W Cru

PhotoelectricUBV photometry of the long period southern eclipsing binary system W Cru gathered over an 18-mo period in 1984–1985 is presented and examined.The light curve is characterized by continuous Beta Lyrae-like variation: unexpected in such a long period (198.5 days) system; together with peculiar irregularities, of the order of 0.1 mag (or more inU) and time-scales of a few days.A high mass model (total mass 70M ) could be made to be roughly consistent with the data, though alternative models of much lower mass are also possible, and may turn out to be preferable, in terms of goodness-of-fit, as well as for theoretical reasons. The low mass models would require, though, the more massive component to be unseen (as now generally supposed for Lyrae itself).The photometry alone, or even combined with a known spectroscopic mass-function, seems unlikely to be able to furnish a single definitive solution, and more guidelines from reliable theoretical expectation may prove helpful in interpreting the data.     

Physical parameters of the O6.5V+B1V eclipsing binary system LS 1135

The 'All Sky Automated Survey' (ASAS) photometric observations of LS 1135, an O-type single-lined binary (SB1) system with an orbital period of 2.7 d, show that the system is also eclipsing performing a numerical model of this binary based on the Wilson–Devinney method. We obtained an orbital inclination     . With this value of the inclination, we deduced masses   M ₁∼ 30 ± 1 M_⊙  and   M ₂∼ 9 ± 1 M_⊙  , and radii   R ₁∼ 12 ± 1 R_⊙  and   R ₂∼ 5 ± 1 R_⊙  for primary and secondary components, respectively. Both the components are well inside their respective Roche lobes. Fixing the T _eff of the primary to the value corresponding to its spectral type (O6.5V), the T _eff obtained for the secondary component corresponds approximately to a spectral type of B1V. The mass ratio   M ₂/ M ₁∼ 0.3  is among the lowest known values for spectroscopic binaries with O-type components.