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1.
S. Evren 《Astrophysics and Space Science》1988,140(1):125-130
The double-lined spectroscopic and eclipsing binary ER Vul was observed in blue and yellow light during the 1984 and 1985 observing seasons. In 1984 four and in 1985 three different light curves in each colour were obtained. The system sometimes is too active and sometimes too quite. The wave-like distortion has been obtained for each light curve and a period of migration has been estimated to be about 8–9 months. The light fluctuations, which are the main characteristics of ER Vul, seems to be related with the wave minimum, (e.g., spotted regions) of the component(s). 相似文献
2.
The photometric observations of ER Vul were obtained in UBV light in 1994, at Birouni Observatory, University of Shiraz, Iran. The three light curves, which are almost complete, have been analyzed separately by means of Wilson and Devinney method (1971). The light curves include proximity effects, wave-like distortions, mutual eclipses, and short term light fluctuations. The appropriate value of the mass ratio of this system was found after extensive searches. ER Vul has a detached configuration where the two components are very nearly fill their Roche lobe. ER Vul has the characteristic of a RS CVn type system. The absolute dimensions for the primary and secondary of this system were calculated from its spectral types and by combining the photometric solution with inferred component radial velocities (Northcott and Bakos, 1967). 相似文献
3.
Photoelectric observations of the peculiar eclipsing variable ER Vul were obtained in blue and yellow light, in the 1981 and 1982 observing seasons. The light curves suffer to change in short time-intervals. The wave-like distortion superimposed on the light curves is clearly seen, but sometimes there is no indication about its existence. The migration period has been estimated roughtly about eight months. Moreover, small-amplitude light fluctuations in the light curves are noticeable. These variations seem to be occur randomly. When the IUE and optical observations are taken into consideration together it is strongly suggested that both of the components in the system ER Vul are too active. 相似文献
4.
Photometric observations of GO Cyg were performed during July–October 2002, in B and V filters (Johnson system). Using the
Wilson's computer codes, the light curve analysis were carried out to find the photometric elements of the system. The O-C
diagram which is based on the observed times of minima as well as those found in the literature, suggests a negative rate
of period variation (i.e. ) for the system. 相似文献
5.
A study of ephemeral active regions (ER) identified on good quality full-disk magnetograms reveals:
- On the average 373 and 179 ER were present on the Sun in 1970 and 1973 respectively. The number varies with the solar cycle.
- The median lifetime of ER depends on observation quality and selection rules but is estimated as about 12 hr for our data.
- The latitude distribution is very broad but not uniform. The distribution peaks near the equator and shows variations similar to distributions of large active regions.
- The longitude distribution is essentially homogeneous.
- The spatial orientation of ER is almost random. In 1973 there is a hint of an excess of new cycle orientations at high latitudes.
6.
Varol Keskin 《Astrophysics and Space Science》1990,169(1-2):165-170
Photoelectric observations of the double-lined spectroscopic and eclipsing binary ER Vul were obtained inB andV colours of Johnson'sUBV system, between 1981 and 1986. The light curves show that the system is sometimes very active and sometimes very quiet and have changes in short time intervals. The were-like distortion, which is superimposed on the light curves, has been obtained. Moreover, small-amplitude light fluctuations in the light curves are noticeable.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
7.
Many available published times of light minima of the late-type binary system ER Vul have been compiled and analyzed using a new method proposed by Kalimeris et al. (1994). It was shown that the orbital period of the system oscillation with a period of about 30.6 years and an amplitude of 3.2×10-6 days while it undergoes a constant period decrease of about dP /P=7.84× 10-8 day / year. The prospective physical mechanisms that could have modulated the orbital period behaviour (periodic or non-periodic), have been studied. We found that a combination of a magnetic activity cycle mechanism and an enhanced stellar wind could explain satisfactorily the period change. 相似文献
8.
New BVR light curves and a photometric analysis of the eclipsing binary star V1430 Aql are presented. The light curves were obtained at the Çanakkale Onsekiz Mart University Observatory in 2004. The light curves are generally those of detached eclipsing binaries, but there are large asymmetries between maxima. New BVR light curves were analysed with an ILOT procedure. Light curve asymmetries of the system were explained in terms of large dark starspots on the primary component. The primary star shows a long‐lived and quasi‐poloidal spot distribution with active longitudes in opposite hemispheres. Absolute parameters of the system were derived.We also discuss the evolution of the system: the components are likely to be pre‐main sequence stars, but a post‐main sequence stage cannot be ruled out. More observations are needed to decide this point. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
Albert P. Linnell 《Astrophysics and Space Science》1973,22(1):13-43
Computer routines permit the solution of eclipsing binary light curves on the Russell Model. With additional automatic point plot routines, the operator has available all necessary supervisory control for an optimum solution. A solution of a synthetic light curve, whose parameters simulate those calculated for the physical system, is an important adjunct to test convergence properties of the physical system solution.Application to EE Peg determines values ofx
x
andx
x
even though secondary minimum is only 0.08 mag. deep. First order perturbation theory is used with the Russell Model to calculate a final triaxial ellipsoid model.Solution of the CM Lac light curve shows that the data require an occultation eclipse at primary minimum, in contrast to the available nomographic solution. The point plot routines demonstrate a substantial improvement effected by the computer solution and show that the latter technique can determine limb darkening coefficients in this partially-eclipsing system.Originally presented at the IAU Colloquium No. 16 held at the University of Pennsylvania, Philadelphia, U.S.A., September 8–11, 1971. 相似文献
10.
H. M. K. Al-Naimiy 《Astrophysics》2001,44(2):233-242
Light curve analysis for three short-period RS CVn-type binaries were performed, using: a) Fourier analysis techniques for light curve changes in the frequency domain; b) photometric curve fit by means of numerical quadratures to develop theoretical light curves appropriate to RS CVn stars. The two methods were applied to the systems ER Vul, BH Vir, and UV Psc. Improved physical and geometrical parameters are found by taking the average of the results measured by the above two methods. 相似文献
11.
Two-colour photoelectric photometry of the eclipsing binary BD + 13o4708 was carried out. Several features such as asymmetry in the branches, light difference between the maxima, an eccentric orbit, a dip around phase 0.2 are distinctive. The new light elements of the system were computed using also the previous times of primary minima given by Walker (1988). 相似文献
12.
本文介绍了北京天文台新研制的光电光度计。本光度计是带有微计算机星天交替式的。可通过计算机控制实现星天和滤光片自动转换。可以很方便地进行随机采集和连续采集,可以实时显示数据和处理观测结果。已经正规观测两年多,取得了一批观测成果,精度可达±0.003~m,能很好地归化到国际系统。 相似文献
13.
N. J. Rattenbury I. A. Bond J. Skuljan P. C. M. Yock 《Monthly notices of the Royal Astronomical Society》2002,335(1):159-169
Simulations of planetary microlensing at high magnification that were carried out on a cluster computer are presented. It was found that the perturbations owing to two-thirds of all planets occur in the time interval −0.5 t FWHM ,0.5 t FWHM with respect to the peak of the microlensing light curve, where t FWHM is typically ∼14 h. This implies that only this restricted portion of the light curve need be intensively monitored for planets – a very significant practical advantage. Nearly all planetary detections in high-magnification events will not involve caustic crossings. We discuss the issues involved in determining the planetary parameters in high magnification events. Earth-mass planets may be detected with 1-m class telescopes if their projected orbital radii lie within about 1.5–2.5 au. Giant planets are detectable over a much larger region. For multiplanet systems the perturbations caused by individual planets can be separated under certain conditions. The size of the source star needs to be determined independently, but the presence of spots on the source star is likely to be negligible, as is the effect of planetary motion during an event. 相似文献
14.
We present an analysis of BV R light curves of an eclipsing binary CK Bootis, a system with a very small mass ratio. The light curves appear to exhibit a typical O'Connell effect. The light curves are analyzed by means of the latest version of the WD program. The asymmetry of the light curves is explained by a cool star spot model. The simultaneous BV R synthetic light curve analysis gives a tiny mass ratio of 0.12, an extremely large fill‐out factor of 0.65, and a very small difference between the component temperatures of 90 K. The absolute parameters of the system were also derived by combining the photometric solutions with the radial velocity data. The mass of the secondary is very low (0.15 M⊙) and it continues losing mass. Thirty seven new times of minimum are reported. It is found that the orbital period of the system has a quasi periodic variation, superimposed on a period increase. The long‐term period increase rate is deduced to be dP/dt = 3.54x10–7 d yr–1, which can be interpreted as being due to mass transfer from the less massive star to the more massive component. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
New CCD observations of the eclipsing binary TZ Boo in BVR bands were carried out in 2006 (presented three new minima) and used together with all published minima to study and update the orbital period of the system TZ Boo by means of an (O–C) diagram. The period variation from 1926 to 2011 is represented by polynomial of eighth degree and indicates period variation of about 9.752 × 10???10 days/yr. We studied light curve stability over 85 yr covering all published observations in the V band and confirm the cyclic light curve variations. 相似文献
16.
The EF Boo eclipsing binary system is studied in the context of optical light curves and radial velocity curves published in the literature. The best‐solution leads to an over‐contact configuration of W–subclass of WUMa systems with a fill‐out factor of 28%. Absolute parameters based on simultaneous solution of light and radial velocity curves are presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
This paper investigates the stability of triangular equilibrium points (L 4,5) in the elliptic restricted three-body problem (ER3BP), when both oblate primaries emit light energy simultaneously. The positions of the triangular points are seen to shift away from the line joining the primaries than in the classical case on account of the introduction of the eccentricity, semi-major axis, radiation and oblateness factors of both primaries. This is shown for the binary systems Achird, Luyten 726-8, Kruger 60, Alpha Centauri AB and Xi Bootis. We found that motion around these points is conditionally stable with respect to the parameters involved in the system dynamics. The region of stability increases and decreases with variability in eccentricity, oblateness and radiation pressures. 相似文献
18.
TheB light curve of BF Vir published by Mallama and Witt (1976) has been re-analyzed using the Wilson and Devinney (1971) approach
and the absolute dimensions have been computed. The system turns out to be a semi-detached system, with an A2V primary and
an evolved G2 undermassive secondary which fills its Roche lobe; the primary, even if detached, is not far from contact. 相似文献
19.
I.N. Belskaya Yu.G. Shkuratov N.M. Shakhovskoy A. Cellino A.A. Ovcharenko V.G. Shevchenko C. Barbieri 《Icarus》2005,178(1):213-221
UBVRI polarimetric observations carried out in 1997-2004 for the F-type Asteroids 302 Clarissa, 419 Aurelia, 704 Interamnia, and 762 Pulcova (V band only) are presented. Asteroid 419 Aurelia is characterized by a negative polarization branch which is unusual for low-albedo asteroids. Its depth is about 1%, while the inversion angle, close to 14°, reaches the smallest value ever observed for asteroids. This is the first definite example of a minor body exhibiting a considerable decrease of both the depth and width of the negative polarization branch in comparison with polarization properties of other low-albedo bodies, mimicking a behavior previously found in laboratory measurements of extremely dark surfaces. The F-type Asteroids 302 Clarissa and 704 Interamnia are also characterized by unusually small inversion angles compared to other asteroid types, while Asteroid 762 Pulcova seems to have an ordinary negative polarization branch. Laboratory measurements of low-albedo samples and computer simulations of light scattering by particles of irregular shapes were made to interpret observational data. We find that an optical homogeneity of regolith microstructure at scales of the order of visible light wavelengths may be responsible for relatively small values of the depth of the negative polarization branch and of the inversion angle. Peculiar features of the F-type asteroids compared to other taxonomic classes are discussed. 相似文献
20.
Two-colour photoelectric observations of the eclipsing binary AT Pegasi have been carried out at the Ege University Observatory. The light curves were analyzed with the methods of Wood and Wilson-Devinney. It is found that the period of the system is decreasing. The system was found to be an Algol type semi-detached binary. The absolute elements of the system are also deduced. 相似文献