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1.
We carried out light curve solutions of four detached binaries with circular orbits, observed by Kepler. As a result their orbital inclinations, temperatures and relative stellar radii were determined. We estimated also their global parameters on the base of the obtained solutions and empirical relation “temperature, luminosity” for MS stars. The out-of-eclipse light curves of KIC 5080652, KIC 9236858 and KIC 11975363 reveal a trend the bigger amplitudes to correspond to single-waved shape while the two-waved shape to be inherent to the smaller amplitudes. This type of variability was attributed to gradually transition between state with two almost opposite cool spots and state with bigger in size polar spot. We detected also several microflares of KIC 11975363 with amplitudes of 0.002–0.003 mag.  相似文献   

2.
KIC 10684673 (TYC 3562-805-1) was observed by the Kepler mission, which obtained nearly 50,000 data points in the short cadence mode from May through June of 2009 for a total of about 33 days. It has been added to the Kepler Eclipsing Binary Catalog as an eclipsing binary. However it is flagged as uncertain in nature. Upon visual inspection, it is found the light curve is not consistent with features present in light curves from typical eclipsing binary systems. Instead, it shows features more consistent with pulsation. In the present study, it is shown the light curve can be satisfactorily modeled by considering the target as single, multi-modal δ Scuti pulsator.  相似文献   

3.
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4.
We present the physical parameters of three short period close binaries using data observed from the Kepler Space Telescope. All of these observations were taken in a single bandpass(which approximates the Johnson V-band). Our three systems are KIC 2715417, KIC 6050116 and KIC 6287172. The first system, KIC 2715417, is considered a semi-detached system with the secondary component filling its Roche lobe. The second system, KIC 6050116, is an overcontact system, while the third system, KIC 6287172, belongs to ellipsoidal variables as deduced from the Roche lobe geometry. For photometric analysis, we used the PHOEBE software package, which is based on the Wilson-Devinney code. Due to lack of spectroscopic data, the photometric mass ratios are determined from the analyses of light curves using the q-search method. The absolute parameters are determined using three different methods(Harmanec, Maceroni Van'tVeer and Gazeas Niarchos).  相似文献   

5.
In this paper we study the field of Kepler open cluster NGC 6866 using the data obtained from Kepler mission collected for a period of 4 years. We search for the red clump (RC) stars amongst the red giant (RG) stars showing solar-like oscillations using median gravity-mode period spacings (ΔP). We find a RG star KIC 8263801 having median gravity-mode period spacing 173.7 ± 6.4 s. We claim based on the median gravity-mode period spacing that KIC 8263801 is a secondary red clump (SRC) star which is massive enough to have ignited Helium burning in a non degenerate core. In the literature, no classification for KIC 8263801 has been provided. This is the first time that a star located in the field of NGC 6866 is classified in this manner.  相似文献   

6.
We present V- and R- band time-series CCD photometry of two contact binaries in the region of the young open cluster NGC 957. The two eclipsing binaries were discovered by Bukowiecki et al., 2009. OEJV 112, 1 and named as V4 and V5, respectively. In the present paper, the first detailed studies of the two contact binary systems are carried out. Firstly, based on the light curves, 28 times of minimum light were detected for V4 and 21 times of minimum light for V5, respectively. Secondly, the orbital periods of V4 and V5 were redetermined as PV4 = 0.40032(5) days and PV5 = 0.30752 (4)days, respectively. The photometric solutions were analyzed by using Wilson Decinny Code. The results reveal that both V4 and V5 are W UMa-type contact binaries with a degree of fV4 = 31(± 1)% and fV5 = 65(± 1)%. The mass ratios were determined to be qV4 = 0.30 and qV5 = 0.19. For V5, the well known O’Connell effect was detected in the dataset, which effect can be explained by employing a dark spot placed on the more massive primary component. Finally, based on the distances of the two contact binaries, which were calculated by using an relation given by Gettel et al., the two contact binaries are judged to be foreground stars in the open cluster NGC 957.  相似文献   

7.
The first complete light curves of two eclipsing binaries in Camelopardalis, NX Cam and V584 Cam, are here presented together with the new observations of the system NSVS 2643686 obtained in 2014. The light curves were modelled using the latest version of the Wilson-Devinney code. Our results show that all the three systems have an extreme mass ratio q < 0.2, two of them, NX Cam and NSVS 2643686, having the fill-out f > 50%, belong to the class of the so called Deep Low Mass Ratio systems (DLMR) but show different physical characteristics. The two above systems are totally eclipsed binaries with the duration of the secondary eclipse of 87 min for NX Cam and 51 min for NSVS 2643686. The other system, V584 Cam, shows a middle fill-out value of f = 33% and low inclination. Using our Times of Minima (ToM) derived from the observations as well as those found in the literature, the ephemerides of the three systems are here revised. The absolute dimensions are estimated and, from statistical diagram, it is found that all the components of the systems follow the general pattern of the well known W UMa contact binaries.  相似文献   

8.
We present BVRI colors of 13 jovian and 8 saturnian irregular satellites obtained with the 2.56 m Nordic Optical Telescope on La Palma, the 6.5 m Magellan Baade Telescope on La Campanas, and the 6.5 m MMT on Mt. Hopkins. The observations were performed from December 2001 to March 2002. The colors of the irregular satellites vary from grey to light red. We have arbitrarily divided the known irregular satellites into two classes based on their colors. One, the grey color class, has similar colors to the C-type asteroids, and the other, the light red color class, has colors similar to P/D-type asteroids. We also find at least one object, the jovian irregular J XXIII Kalyke, that has colors similar to the red colored Centaurs/TNOs, although its classification is insecure. We find that there is a correlation between the physical properties and dynamical properties of the irregular satellites. Most of the dynamical clusters have homogeneous colors, which points to single homogeneous progenitors being cratered or fragmented as the source of each individual cluster. The heterogeneously colored clusters are most easily explained by assuming that there are several dynamical clusters in the area, rather than just one, or that the parent body was a differentiated, heterogeneous body. By analyzing simple cratering/fragmentation scenarios, we show that the heterogeneous colored S IX Phoebe cluster, is most likely two different clusters, a grey colored cluster centered on S IX Phoebe and a light red colored cluster centered on S/2000 S 1. To which of these two clusters the remaining saturnian irregulars with inclinations close to 174° belong is not clear from our analysis, but determination of their colors should help constrain this. We also show through analysis of possible fragmentation and dispersion of the six known uranian irregulars that they most likely make up two clusters, one centered on U XVI Caliban and another centered on U XVII Sycorax. We further show that, although the two objects have similar colors, a catastrophic fragmentation event creating one cluster containing both U XVI Caliban and U XVII Sycorax would have involved a progenitor with a diameter of ∼395 km. While such an event is not impossible it seems rather improbable, and we further show that such an event would leave 5-6 fragments with sizes comparable to or larger than U XVI Caliban. The stable region around Uranus has been extensively searched to limiting magnitudes far beyond that of U XVI Caliban. The fact that only U XVI Caliban, the larger U XVII Sycorax and four much smaller objects have been found leaves us with a distribution not compatible with a catastrophic event with such a large progenitor. The most likely solution is therefore two separate events creating two uranian dynamical clusters.  相似文献   

9.
We present the first CCD sets of complete light curves for two W Ursae Majoris Systems, UCAC3 276-106147 and NSVS 7377756. These light curves are here analyzed and modelled using the latest version of the Wilson-Devinney Code. We found that UCAC3 276-106147 is a W-subtype shallow-contact eclipsing binary (fill-out factor 7.5%), with a mass ratio of q = 2.88 (1/q = 0.347), a small temperature difference between the components of about ΔT =200K. NSVS 7377756 is an H-subtype binary system with a high mass ratio of q = 1.09 (1/q = 0.947), a weak degree of contact factor f = 3.8% and a temperature difference between the components of ΔT = 398 K. The light curves of both the systems appear to be unspotted. By using our 4 and 7 times of minimum light and the 30 and 104 ToMs extract from the SWASP observations, respectively for UCAC3 276-106147 and NSVS 7377756, the orbital periods are here revised. The elements obtained from this analysis are used to compute the physical parameters of the systems combining our photometric solution with the 3-D correlation obtained for contact binaries by Gazeas (2009). Based on these estimated parameters the evolutionary state of the components of the systems is investigated and discussed.  相似文献   

10.
We present new photometric observations for the eclipsing binary DF CVn, and determined five light minimum times. By using the Wilson–Devinney code, two sets of photometric solutions were deduced from our observations in 2009. The asymmetric light curves obtained on 2009 March 5 were modeled by a dark spot on the more massive component. The results indicate that DF CVn is a W-type weak-contact binary, with a mass ratio of q ～ 0.28 and an overcontact degree of f ～ 20%. From the O ? C curve of minimum times, it is found that there exists a cyclic variation, whose period and semi-amplitude are P3 = 17.2(±0.9) year and A = 0.d0070(±0.d0008), respectively. This kind of cyclic oscillation may possibly result from the light-time effect due to the presence of an unseen third body. This kind of additional body may extract angular momentum from the central system. The low-amplitude changes of the light curves on a short-time scale (e.g., half a month) may be attributed to the dark spot activity, which may result in angular momentum loss via magnetic breaking. With angular momentum loss, the weak-contact binary DF CVn will evolve into a deep-contact configuration.  相似文献   

11.
We obtained complete V and Rc light curves of the eclipsing binary V380 Gem in 2012. With our data we were able to determine six new times of minimum light and refine the orbital period of the system to 0.3366088 days. The 2003 version of the Wilson–Devinney code was used to analyze the light curves in the V and Rc bands simultaneously. It is shown that V380 Gem may be classified as an W-type W Ursae Majoris system with a high mass ratio q = 1.45, a degree of contact f = 10.6% the same temperature for both the components (ΔT = 10 K) and an orbital inclination of i  = 81.5°. Our observations show symmetric light curves in all passbands with brightness in both maxima at the same level. The absolute dimensions of V380 Gem are estimated and its dynamical evolution is inferred.  相似文献   

12.
We present a new multicolor CCD photometry and light curve analysis of two eclipsing binary systems, 1SWASP J133417.80 + 394314.4 and V2790 Orion. The photometric solutions for both binaries were carried out using the updated version of the Wilson– Devinney code. The results showed that first systems is A- type W UMa with mass ratios q = 0.158 while the second system is W- type with q = 3.2. The systems show over contact configuration with fill-out factors of f = 43% and 14% respectively. We calculated the orbital and absolute physical parameters for both systems and investigated their evolutionary state.  相似文献   

13.
SuperWASPJ222302.02+195031.8 is an eclipsing binary with an orbital period about 0.22517657 days that is close to the short-period limit of contact binaries. Multi-color photometric light curves of the short-period binary in B, V, Rc and Ic bands are presented and analyzed by using the Wilson–Devinney (W–D) method. It is discovered that the system is a semi-detached binary where the secondary component is already filling the critical Roche lobe, while the primary is filling just 77.1% of its Roche lobe. The temperature of the primary is about 4300 K, and the temperature difference between the two components is about 500 K. The asymmetries in the light curves are explained by the coverage of stellar dark spots on the less massive component via magnetic activity. An analysis of all available eclipse times suggests that there are no any changes in the O-C diagram. This may indicate that there are no mass transfers between the two components. The semi-detached configuration with the dark spot on the surface of the lobe-filling secondary and no variations in the orbital period make the binary an interesting target for further investigations.  相似文献   

14.
Ignacio Ferrín 《Icarus》2008,197(1):169-182
We present the secular light curve of Comet 2P/Encke in two phase spaces, the log plot, and the time plot. The main conclusions of this work are: (a) The comet shows activity at perihelion and aphelion, caused by two different active areas: Source 1, close to the south pole, active at perihelion, and Source 2, at the north pole, centered at aphelion. (b) More than 18 physical parameters are measured from the secular light curves, many of them new, and are listed in the individual plots of the comet. Specifically we find for Source 1 the location of the turn on and turn off points of activity, RON=−1.63±0.03 AU, ROFF=+1.49±0.20 AU, TON=−87±5 d, TOFF=+94±15 d, the time lag, LAG(q)=6±1 d, the total active time, TACTIVITY=181±16 d, and the amplitude of the secular light curve, ASEC(1,1)=4.8±0.1 mag. (c) From this information the photometric age and the time-age defined in Ferrín [2005a. Icarus 178, 493-516; 2006. Icarus 185, 523-543], can be calculated, and we find P-AGE = 97 ± 8 comet years and T-AGE = 103 ± 9 comet years (cy). Thus Comet 2P/Encke is an old comet entering the methuselah stage (100 cy < age). (d) The activity at aphelion (Source 2), extends for TACTIVITY=815±30 d and the amplitude of the secular light curve is ASEC(1,Q)=3.0±0.2 mag. (e) From a new phase diagram an absolute magnitude and phase coefficient for the nucleus are determined, and we find RNUC(1,1,0)=15.05±0.14, and β=0.066±0.003. From this data we find a nucleus effective diameter DEFFE=5.12(+2.5;−1.7) km. These values are not much different from previous determinations but exhibit smaller errors. (f) The activity of Source 1 is due to H2O sublimation because it shows curvature. The activity of Source 2 might also be due to H2O due to the circumstantial situation that the poles point to the Sun at perihelion and aphelion. (g) We found a photometric anomaly at aphelion, with minimum brightness between +393 and +413 days after perihelion that may be an indication of topography. (h) We have re-reduced the 1858 secular light curve of Kamel [1991. Icarus 93, 226-245]. There are secular changes in 7 physical parameters, and we achieve for the first time, an absolute age calibration. We find that the comet entered the inner Solar System and began sublimating in 1645±40 AD. (i) It is concluded that the secular light curve can place constraints on the pole orientation of the nucleus of some comets, and we measure the ecliptic longitude of the south pole of 2P/Encke equal to 213.2±4.5°, in excellent agreement with other determinations of this parameter, but with smaller error. (j) Using the observed absolute magnitude of 1858 and 2003 and a suitable theoretical model, the extinction date of the comet is determined. We obtain ED=2056±3 AD, implying that the comet's lifetime is 125±12 revolutions about the Sun after entering the inner Solar System.  相似文献   

15.
We present the results of searching for new candidates of eclipsing binaries with eccentric orbits in the ASAS Catalog of Variable Stars (ACVS) using publicly available data from the All Sky Automated Survey (ASAS) and the Transiting Exoplanet Survey Satellite (TESS). Unsupervised machine learning techniques were applied to find anomalies among the light curves of eclipsing binaries. The light curves modeling were performed using JKTEBOP code. The pulsation analysis was done with FAMIAS. We identified 19 new eclipsing binary candidates with non-zero eccentricities in the ACVS, including 10 candidates with eccentricities e ≥ 0.1. Estimates of eccentricities are given. We also report on possible presence of the small-amplitude stellar pulsations at least in two of the reported systems.  相似文献   

16.
The eclipsing binary OO Peg consist of two late-A type stars in circular orbit with a period of 2.985 days. I use the high-resolution spectroscopic and extensive light curves from the ASAS and Hipparcos survey to measure the physical properties of the system. Previous attempts to model the light and radial velocity curves of the system have met with limited success, primarily because of the lack of a accurate photometric data. The system shows no signs of stellar activity, it is slowly rotating, has not been detected period changes, and there is no pulsational signs in the photometric data. I show the location of the components in effective temperature vs. luminosity diagram compared to the instability region limits established from eclipsing binary components. While more than 25 system have been plotted to diagram, about six single stars and OO Peg components do not show any pulsational frequencies. They are apparently constant stars lie within the pulsation instability region. I speculate as to the possible causes of this picture.  相似文献   

17.
This paper presents new CCD Bessell BVRI light curves and photometric analysis of the Algol-type binary star TX Her. The CCD observations were carried out at Çanakkale Onsekiz Mart University Observatory in 2010. New BVRI light curves from this study and radial velocity curves from Popper (1970) were solved simultaneously using modern light and radial velocity curves synthesis methods. The general results show that TX Her is a well-detached eclipsing binary, however, both component stars fill at least half of their Roche lobes. A significant third light contribution to the total light of the system could not be determined. Using O–C residuals formed by the updated minima times, an orbital period study of the system was performed. It was confirmed that the tilted sinusoidal O–C variation corresponds to an apparent period variation caused by the light travel time effect due to an unseen third body. The following absolute parameters of the components were derived: M1 = 1.62 ± 0.04 M⊙, M2 = 1.45 ± 0.03 M⊙, R1 = 1.69 ± 0.03 R⊙, R2 = 1.43 ± 0.03 R⊙, L1 = 8.21 ± 0.90 L⊙ and L2 = 3.64 ± 0.60 L⊙. The distance to TX Her was calculated as 155 ± 10 pc, taking into account interstellar extinction. The position of the components of TX Her in the HR diagram are also discussed. The components are young stars with an age of ～500 Myr.  相似文献   

18.
The new multi-color BVRI photometric light curves of the short-period eclipsing binary GSC 3576-0170 were obtained on two consecutive nights (October 5 and 6, 2009). With the 2003 version of Wilson–Devinney program, the precise photometric solutions are derived for the first time. The result shows that GSC 3576-0170 is a semi-detached binary system with a large temperature difference of approximately 1490 K. The light-curve distortions are further explained by a hot spot on the secondary component through mass transfer via a stream hitting the facing surface of the secondary component. By analyzing all available light minimum times, we also derived an update ephemeris and found for the first time a possible periodic oscillation with an amplitude of 0.0038 days and a period of 4.3 years. The periodic oscillation could be explained either by the light-time effect due to a presumed third component or by magnetic activity cycle of the system.  相似文献   

19.
This paper presents new CCD BVRI light curves of the newly discovered RS CVn eclipsing binary star DV Psc. From the asymmetric light curves outside the eclipse, we find there are two depressions in the phase ranges 0.3–0.45 and 0.6–0.9, respectively. By analyzing the light curves using the Wilson–Devinney program, the four photometric solutions of the system are obtained and the starspot parameters are also derived. It turns out that the case of two spots being on the primary is most successful in reproducing the light curve distortion of DV Psc. Moreover, analysis the longitudes of spots suggests that there are two active longitude belts (one is about 90°, the other is about 270°). At the same time, on 22 November 2008, the first flare-like event was detected on DV Psc at phase 0.35 whose duration was about 13.5 min. These findings reveal that DV Psc has a high degree of magnetic activity.  相似文献   

20.
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