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1.
We solve the uvbyRI light curves obtained by Wolf (1994) with a CCD photometer. Wolf did not solve the light curves, while particular interest in them stems from the fact that a secondary minimum, which other observers failed to detect, is clearly seen in the byRI light curves. This enables us to consider a new eclipse model in which we hypothesize that the secondary component at primary minimum completely obscures the primary, smaller B star, but, at the same time, the light from a third star is observed. Based on this hypothesis, we computed the brightness of each of the three stars for the six bands by analyzing the depths of the primary and secondary minima. Satisfactory agreement between theoretical and observed light curves was achieved by assuming the following parameters for the stars: effective temperature T 1=17000 K, radius R 1 = 2.5 R ⊙, spectral type Sp1 = B3—B4 for the primary; T 2=5700 K, R 2 = 8.4 R ⊙, Sp2 = G0—G2 for the secondary; and T 3=29000 K, R 3 = 1.0 R ⊙, Sp3=B0 for the third star. In the Hertzsprung-Russell diagram, the first star lies on the zero-age main sequence, the second is on the way from the birthline to the main sequence in the region of giants, and the third falls within the region of hot subdwarfs.  相似文献   

2.
This study presents an investigation of the orbital period variations of five Algol type binaries, UX Leo, RW Mon, EQ Ori, XZ UMa and AX Vul based on all available minima times. The O–C diagrams of all systems exhibit a periodic variation superimposed on a downward parabolic segment. The mass loss due to magnetic braking effect in the cooler components is assumed to account for the parabolic variation with a downward shape, while it is suggested that the light-time effect (LITE) due to an unseen component around the eclipsing binaries explains the tilted sinusoidal changes in their O–C diagrams. The orbital period decrease rates for the systems are estimated as approximately between about 0.7 and 2.5 s per century. It is clearly seen that mass loss effect is more dominant than the expected mass transfer for classical Algols in this study. The minimum mass of the probable third bodies around the eclipsing pairs was calculated to be ?0.5 M⊙ except for UX Leo, in which it was estimated to be approximately 0.9 M⊙. In order to search for third lights in the light curves of five systems, the V-light curves of the systems were analyzed and their physical and photometric parameters were determined. For UX Leo, a significant third light contribution was determined. We found a very small third light that can be tested using multi-color light curves, for RW Mon, EQ Ori and XZ UMa, while a third light for AX Vul could not be exposed.  相似文献   

3.
《New Astronomy Reviews》2000,44(1-2):171-175
Four problems are discussed. (1) Model light curves show significant increase of the disk luminosity during quiescence, an effect which is not present in the observed light curves. It is suggested that the slope of the lower branch of the Σ−Te relation should be significantly decreased. (2) The width – Porb relation for narrow outbursts is well reproduced with model data for αhot=0.2. The bimodal distribution of outburst durations and, in particular, the origin of wide outbursts and the nature of their width – Porb relation, require explanation. (3) It is suggested that problems with the thermal-tidal instability (TTI) model for superoutbursts might be solved by a hybrid model, combining the TTI model with the irradiation-enhanced mass-transfer model. A strong argument in favour of irradiation is provided by the ratio of the irradiating flux to the intrinsic flux of the secondary component, which turns out to be very large in the case of dwarf novae showing superoutbursts, with U Gem being a borderline case. (4) Characteristic time-scales observed during dwarf nova outbursts depend on the viscous time-scale, allowing an empirical determination of α. Three independent determinations, based on the rates of decline following outburst maximum, the UV delay observed during rising light, and the widths of outbursts, give consistently αhot≈0.2. It should be added, however, that those time-scales depend also strongly on the radius of the disk. In this context it is disturbing to note that the observed disk radii appear to be smaller than those resulting from model calculations.  相似文献   

4.
We present the first CCD sets of complete light curves for the W Ursae Majoris system NSVS 1557555.The observations were performed in the B, V and Ic bands using the 0.25  m telescope of the Stazione Astronomica Betelgeuse Northern Italy, during 8 nights in October and November 2016.Based on our new eleven Time of Minima (ToM), and two recent ones found in bibliography, the short orbital period of the system is confirmed and revised to P = 0.2725163 days .A reasonable fit of the synthetic light curves of the data indicate that NSVS 1557555 is a late-type (K1+K3) shallow contact binary system of W-Subtype of the W Ursae Majoris systems, with a mass ratio of q = 1.8, a degree of contact factor f = 12.5%, a temperature difference between the components of 240K and inclination i = 85°.The light curves show asymmetries at the maxima with the maximum at phase 0.75 higher the other one (inverse O’Connell effect).To explain the light asymmetries we used a model that involves an hot spotted region on the surface of the cooler star.The definitive solution is only possible with a large amount of third light (L3 = 0.58 in B Filter). It may come from a hot tertiary component.The absolute dimensions of the system are estimated. From the logM-logL diagram it is seen that both components of NSVS 1557555 follow the general pattern of the W subtype W Ursae Majoris systems.The orbital angular momentum is compared with those of other W UMa type binaries and is normal.  相似文献   

5.
We present the first infrared light curves of the binary V1430 Aql, in the bands J and K, plus V, R and I light curves and spectra covering the ranges of Hβ, Hα and Ca II-IRT lines. Our VRIJK data, together with published radial velocity curves, are analyzed to determine the orbital and stellar parameters of the system. Both stellar components present spectroscopic evidence of chromospheric activity, with emission excesses in the Hβ, Hα and Ca II-IRT lines. The measured ratio of the lines Hβ/Hα emission excesses can be interpreted as originated in plages. Our light curves also show photometric evidence of cool spots at least on one of the stars.  相似文献   

6.
The aim of the present paper will be to extend our new methods of analysis of the light curves, of eclipsing binary systems, consisting of spherical components, by Fourier approach to eclipses oftransit type — which arise when the eclipsing component happens to be smaller of the two. Our present principal concern will be transit eclipses, terminating in annular phase, of stars characterized by arbitrary radially-symmetrical distribution of brightness over their apparent discs — a phenomenon which will cause the light of the system to vary continuously during annular phase. In the first section which follows this abstract, an outline of the problem at issue will be given. Section 2 has been devoted to an analysis of light changes arising in the course of partial phases of transit eclipses; and the concluding Section 3 will contain an analysis of the corresponding light changes, during annular phase. Unlike for occultation eclipses considered in our previous paper (cf. Kopal, 1975b), the momentsA 2m of the light curves due to eclipses of transit type can again be expressed in terms of the geometrical elements of such eclipses in a closed form for limb darkening characterized by any value ofn; but the use of such functions will require auxiliary tables (now in preparation) for applications to practical cases. A parallel treatment of partial eclipses of the occultation or transit type — eclipses which stop short of totality or annular phase — is being postponed for a subsequent communication.  相似文献   

7.
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 RIc 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.  相似文献   

8.
In this paper we parameterize the photoelectric waves in the light curves of BH Vir in B and λ 5125Å bands by Hoffmann (1982) by using the Wilson-Devinney program. The principal results are as follows: (1) The mass ratio obtained from the photoelectric light curves is q =m2/m1 = 0.967. (2) The photosphere temperature of the primary is T1 = 5947 K. (3) The distortion waves in the light curves can be fitted satisfactorily with the spot model of two hot spot activities on the primary star.  相似文献   

9.
We present six \(\mbox{V}R_{c}I_{c}\) light curves of UX CrB from observations carried out from 2011–2015. We also obtained three optical spectra using the 2.16-m optical telescope and LAMOST survey at the national astronomical observatories. We classified its spectral type as \(\mbox{G2}\pm\mbox{2V}\). We noticed that there are strong absorptions in the Hα, Hβ, Ca ii H&K and infrared triplet lines in the observed spectra. By subtracting away the photospheric contribution, we also noticed that there are small excess emissions in these chromospheric active lines, which indicate there are weak chromospheric activities. We tried and obtained four photometric solutions with different spot positions from our full and high time-resolution light curves in 2012, using the updated Wilson-Devinney code. The model with two spots on the primary produced the best result for explaining the observed light curves from 2012. Moreover, we explained all other light curves based on our photometric solution using our 2012 light curves. There are two active longitudes at about 68° and 255°. We noticed that the starspots have both long-time (years) and short-time (about two months) variation by analyzing the light curves and its starspot parameters. There is also an obvious oscillation of light curve maximum between 0.25 and 0.75 phases by analyzing the values of \(\mbox{Max.~I} - \mbox{Max.~II}\). We conclude UX CrB are the evolved main-sequence stars with strong photometric and chromospheric activities.  相似文献   

10.
UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution and activity of the sources. The emission by OH, NH, CN, C3, CH, C2, NH2, and OI, are analyzed, as well as the light scattered by the dust. It is found that a simple model reproduces fairly well the impact light curves of all species combining the production of the observed molecules and the expansion of the material throughout the slit. The impact light curves are consistent with velocities of 400-600 m/s. Their modeling requires a three-step dissociation sequence “Grand-Parent → Parent → Daughter” to produce the observed molecules. The rotational light curve for each species is explained in terms of a single model with three sources. The dust component can however not easily be explained that way.  相似文献   

11.
1SWASP J204932.94-654025.8 (hereafter J2049) is a newly discovered eclipsing binary system with an orbital period of 0.2299103 days. BVRc 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.  相似文献   

12.
An algorithm for the solution of Fredholm's equations of the first kind describing light curves of WR + O binary systems on a set of nonnegative monotonically decreasing convex functions is developed. The algorithm is applied to the narrow-band continuum The λ4244 Ålight curve of the eclipsing binary V444 Cygni (WN5 + O6). Reliable information about the distribution of the linear absorption coefficientα (r) and the velocity law in the extended photosphere of the WN5 star is obtained from the analysis. Recent accurate spectrophotometric estimate of the luminosity ratio of the components in the binary was used to establish the relationship between the two geometrical parameters of the model: the radius of the O6 star and the orbital inclination. It is shown that the flow of matter in the WN5 photosphere is accelerating and that the value of the acceleration is relatively low. The expansion velocity at the distance r ? 3.8R ⊙ (at whichτ4244(r) ? 1) reaches a few hundreds km/s, i.e., the flow at this point is supersonic.  相似文献   

13.
Computer simulations of light scattering by particulate surfaces and single particles forming these surfaces are presented. The ray optics approximation is used. Three types of particles are studied: spheres, cubes, and very irregular particles that are generated with an auxiliary random Gaussian field. The surfaces of the particles are represented as an arrangement of triangular facets. For the Monte Carlo ray tracing 106−107 rays were used. The ray tracing verifies Shkuratov et al.'s (Icarus 137 (1999) 235-246) spectral albedo model for powder-like media. We derive a useful relationship between the hemispheric albedo, Aint, and the bi-directional reflectance, R, at phase angle 30°: logR(30°)=1.088logAint. This relationship provides a way to estimate bi-directional reflectance spectra from laboratory spectra measured with an integrating sphere for surfaces composed of particles of irregular shapes. We study also phase angle curves of the nonzero scattering matrix elements, F11, −F12/F11, F22/F11, F33/F11, F34/F11, F44/F11, for single particles and media thereof. Randomly shaped particles show smoother phase angle behavior than particles with regular shapes that display distinct features. For media consisting of spheres the glory and primary rainbow both are prominent even in the case of conservative (nonabsorbing) scattering. On the other hand, such media clearly exhibit the depolarization effect, showing a significant role of multiple scattering between particles. For media composed of semitransparent cubes the retroreflector spike and a very deep negative polarization branch at small phase angles are observed. We demonstrate that, in the geometric optics approximation, neither a medium of spherical particles nor one of cubic particles is appropriate for modeling light scattering behavior of regolith-like surfaces.  相似文献   

14.
The first CCD photometric complete light curves of the eclipsing binary NSVS 7051868 were obtained during six nights in January 2016 in the B, V and Ic bands using the 0.25 m telescope of the Stazione Astronomica Betelgeuse in Magnago, Italy.These observations confirm the short period (P = 0.517 days) variation found by Shaw and collaborators in their online list (http://www.physast.uga.edu/~jss/nsvs/) of periodic variable stars found in the Northern Sky Variability Survey.The light curves were modelled using the Wilson–Devinney code and the elements obtained from this analysis are used to compute the physical parameters of the system in order to study its evolutionary status.A grid of solutions for several fixed values of mass ratio was calculated.A reasonable fit of the synthetic light curves of the data indicate that NSVS 7051868 is an A-subtype W Ursae Majoris contact binary system, with a low mass ratio of q = 0.22, a degree of contact factor f = 35.5% and inclination i = 85°. Our light curves shows a time of constant light in the secondary eclipse of approximately 0.1 in phase. The light curve solution reveals a component temperature difference of about 700 K. Both the value of the fill-out factor and the temperature difference suggests that NSVS 7051868 is a system in a key evolutionary stage of the Thermal Relaxation Oscillation theory.The distance to NSVS 7051868 was calculated as 180 pc from this analysis, taking into account interstellar extinction.  相似文献   

15.
This paper presents the first analysis of spectroscopic and photometric observations of the neglected southern eclipsing binary star, QY Tel. Spectroscopic observations were carried out at the South African Astronomical Observatory in 2013. New radial velocity curves from this study and V light curves from the All Sky Automated Survey were solved simultaneously using modern light and radial velocity curve synthesis methods. The final model describes QY Tel as a detached binary star where both component stars fill at least half of their Roche limiting lobes. The masses and radii were found to be 1.32 (± 0.06) M⊙, 1.74 (± 0.15) R⊙ and 1.44 (± 0.09) M⊙, 2.70 (± 0.16) R⊙ for the primary and secondary components of the system, respectively. The distance to QY Tel was calculated as 365 (± 40) pc, taking into account interstellar extinction. The evolution case of QY Tel is also examined. Both components of the system are evolved main-sequence stars with an age of approximately 3.2  Gy, when compared to Geneva theoretical evolution models.  相似文献   

16.
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   

17.
The aim of the present paper will be to develop methods for computation of the Fourier transforms of the light curves of eclipsing variables — due to any type of eclipses — as a function of a continuous frequency variablev. For light curves which are symmetrical with respect to the conjunctions (but only then) these transforms prove to be real functions ofv, and expressible as rapidly convergent expansions in terms of the momentsA 2m+1 of the light curves of odd orders. The transforms are found to be strongly peaked in the low-frequency domain (attaining a maximum forv=0), and become numerically insignificant forv>3. This is even more true of their power spectra.The odd momentsA 2m+1 — not encountered so far in our previous papers — are shown in Section 3 of the present communication to be expressible as infinite series in terms of the even momentsA 2m well known to us from Papers I–IV; and polynomial expressions are developed for approximating them to any desired degree of accuracy. The numerical efficiency of such expressions will be tested in Section 4, by application to a practical case, with satisfactory results.Lastly, in Section 5, an appeal to the Wiener-Khinchin theorem (relating the power spectra with autocorrelation function of the light curves) and Parseval's theorem on Fourier series will enable us to extend our previous methods for a specification of quadratic moments of the light curves in terms of the linear ones.  相似文献   

18.
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   

19.
Light curve modeling for the newly discovered super contact low-mass WUMa system 1SWASPJ092328.76+435044 was carried out by using a new BVR complete light curves. A spotted model was applied to treat the asymmetry of the light curves. The output model was obtained by means of Wilson–Devinney code, which reveals that the massive component is hotter than the less massive one with about ΔT ～ 40 K. A total of six new times of minima were estimated. The evolutionary state of the system components was investigated based on the estimated physical parameters.  相似文献   

20.
We observed Mrk 421 in V and R band using the 1.0 m telescope at Weihai Observatory of Shandong University since 2009 April to 2012 May. The available historical data in B and V band were also assembled for constructing light curves. The brightness of Mrk 421 ranges from 11.40 to 16.14 in the B band light curve, and from 11.38 to 14.56 in the V band. Analyses with the Jurkevich method and the structure function method showed a possible period of about 1.36 years for its long periodic variability. This period could be explained by a close binary black hole system (BBHS) model with a primary black hole mass of 1.70×108 M ⊙ and a secondary ～(0.49–2.9)×107 M ⊙. We showed the color variability of Mrk 421, a bluer when brighter behavior during its lower state. Analyses of spectral index variations show that only a host galaxy contribution is not sufficient to explain the spectral index variations in Mrk 421, and some intrinsic mechanism is needed.  相似文献   

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