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1.
New ground-based BV RI CCD observations of the eclipsing binary systems NN Vir and YY CrB are analyzed and illustrated. New times of minima are given and new ephemerides are proposed. The light curves are analyzed with the Wilson-Devinney light curve synthesis code and new geometric and photometric elements are derived. These elements are used together with the available spectroscopic data to compute absolute elements. The evolutionary status of each system is studied by means of mass-radius diagrams. The systems NN Vir and YY CrB are found to be A-type and W-type W UMa systems, respectively.  相似文献   

2.
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   

3.
New photoelectric times of maximum light of the large amplitude SX Phoenicis star CY Aquarii are analyzed together with times of maximum light in the literature. The general shape of the fitted curve of the observed minus calculated (O-C) times of maximum light suggest the duplicity of the variable star, which causes long-term period variations in the light-time. The period changes of CY Aqr are probably consequences of a continuously increasing period combined with the light-time effect in a binary system. The secondary companion is less massive. Some spectroscopic orbital elements are derived from the O-C diagram. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
Spectra in the wavelength range 4230–9150 Å and the first light curves of Z Vul in the infrared J, H and K bands are presented. Our infrared JHK light curves and radial velocities, together with published radial velocity and UBV data are analyzed in order to determine a new set of stellar parameters. This allows us to determine new absolute parameters of the stellar components, the interstellar reddening and the distance to the system. We discuss the rotation of the primary star, finding that must be rotating faster than synchronous. From the visual–infrared photometry we find no evidence of IR excess in the system.  相似文献   

5.
NewUBV observations of the classical Algol system AW Peg were presented. The photometric minima times were collected and used together with the new determinations in a period study. No sign of any period change was found from observations covering more than sixty years. TheB andV light curves are analyzed by means of the Wilson-Devinney approach. It was verified that the system is semi-detached with a Roche lobe filling secondary.  相似文献   

6.
Revised light elements of the RR Lyrae variable star DH Pegasi are presented together with a newBV light curve.  相似文献   

7.
An analysis of X-ray and optical light curves of the magnetic cataclysmic variable (MCV) BY Cam is presented. This system is one of three MCVs in which the spin period of the white dwarf and the binary orbital period differ by ∼1 per cent. As such these 'BY Cam' stars are important objects with which to probe the field structure of the magnetic white dwarf and ultimately the nature of synchronization of AM Her binaries. We confirm asynchronous rotation of the magnetic white dwarf with respect to the binary. We find evidence that the accretion stream accretes directly on to the white dwarf as in AM Her systems, but further, the stream impacts on to different magnetic poles over the course of the beat period. We present evidence that the optical and hard X-ray light curves modulate in phase, but together they are out of phase with the soft X-ray light curve. We confirm the spin down of the white dwarf which is expected to lead to the synchronization of the spin and orbital periods of BY Cam.  相似文献   

8.
Photometric data on the southern mid‐F type close eclipsing binary system SU Ind from the Carter Observatory (NZ) were examined, together with a light curve obtained from the Hipparcos Epoch Photometry (HEP) database. The system appears detached, although appreciably evolved from the Zero Age Main Sequence. The HEP period must be accurate for its own epoch, but it is significantly different from the reference (Hoffmeister 1956) value. This is difficult to explain, given the uncomplicated nature of the light curve. The apparent discrepancy can be reconciled with a period that has remained almost constant over the 40 year interval between the epochs by assuming some confusion between the almost equal depth minima. The near‐equality of components raises issues of determinacy in light curve analysis, which are reviewed against the presentation of relevant numerical curve‐fitting details. The system is of physical interest, in that it is close to the start of the ‘active’ range of spectral types. Its stars have relatively rapid rotation speeds and probably shallow convective subphotospheric layers. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

9.
Although comparatively bright, the cataclysmic variable GY Hya has not attracted much attention in the past. As part of a project to better characterize such systems photometrically, we observed light curves in white light, each spanning several hours, at Bronberg Observatory, South Africa, in 2004 and 2005, and at the Observatório do Pico dos Dias, Brazil, in 2014 and 2016. These data permit to study orbital modulations and their variations from season to season. The orbital period, already known from spectroscopic observations of Peters and Thorstensen (2005), is confirmed through strong ellipsoidal variations of the mass donor star in the system and the presence of eclipses of both components. A refined period of 0.34723972 (6) days and revised ephemeries are derived. Seasonal changes in the average orbital light curve can qualitatively be explained by variations of the contribution of a hot spot to the system light together with changes of the disk radius. The amplitude of the ellipsoidal variations and the eclipse contact phases permit to put some constraints on the mass ratio, orbital inclination and the relative brightness of the primary and secondary components. There are some indications that the disk radius during quiescence, expressed in units of the component separation, is smaller than in other dwarf novae.  相似文献   

10.
New time-series photometric observations of BL Cam in the V band and white light were made during 2005 to 2007 at the Xinglong Station of China. The frequency analysis confirms two closely separated frequencies, 25.181 d-1 and 25.571 d-1, but the frequency of 31-32 d-1 reported in the literature was not detected in the new data. New times of maximum light were determined from both our light curves and those available on Internet, allowing a more comprehensive study of the O - C diagram, together with the times of maximum light in the literature. A new interpretation, including the period increasing before 1988 and decreasing since 1992 of BL Cam and the light-time effect in a binary system, looks plausible.  相似文献   

11.
A new four-image gravitational lens system, B0712+472, has been discovered during the Cosmic Lens All-Sky Survey. This system consists of four flat-spectrum radio images that are also seen on a Hubble Space Telescope ( HST ) image, together with the lensing galaxy. We present MERLIN, VLA and VLBA maps and WHT spectra of the system as well as the HST images. The light distribution of the lensing galaxy is highly elongated and so too is the mass distribution deduced from modelling. We suggest a redshift of ∼1.33 for the lensed object; the lens redshift will require further investigation. The discovery of this new system further increases the ratio of four-image to two-image lens systems currently known, exacerbating problems of required ellipticity of matter distributions in lensing galaxies.  相似文献   

12.
Observations of the light curves of asteroid Nos. 6, 7, 8, 16, 20, 22 are presented together with a discussion of the results.  相似文献   

13.
CCD photometry of the short-period binary stars KQ Gem and V412 Her is presented, together with some spectroscopic observations of KQ Gem. Although both systems are classified in the General Catalogue of Variable Stars as having light curves of EB/KW type, our data and analyses, involving light-curve synthesis and stellar surface imaging, show that KQ Gem is an EB system that is in marginal contact and has an enhanced bright region around the substellar point on the secondary component, whilst V412 Her is an EW system, a true contact binary with a mass ratio of 0.46 and both stars having the same surface brightness. The properties of the components of the two systems are compared with other marginal-contact and contact binaries, and a plea is repeated for more theoretical work on the mass/energy interchanges in contact binaries.  相似文献   

14.
We present two new sets of complete light curves of EQ Tauri (EQ Tau) observed in 2000 October and 2004 December. These were analysed, together with the light curves obtained by Yang & Liu in 2001 December, with the 2003 version of the Wilson–Devinney code. In the three observing seasons, the light curves show a noticeable variation in the time-scale of years. The more massive component of EQ Tau is a solar-type star (G2) with a very deep convective envelope, which rotates about 80 times as fast as the Sun. Therefore, the change can be explained by dark-spot activity on the common convective envelope. The assumed unperturbed part of the light curve and the radial velocities published by Rucinski et al. were used to determine the basic parameters of the system, which were kept fixed for spot modelling in the three sets of light curves. The results reveal that the total spotted area on the more massive component covers 18, 3 and 20 per cent of the photospheric surface in the three observing seasons, respectively. Polar spots and high-latitude spots are found. The analysis of the orbital period has demonstrated that it undergoes cyclical oscillation, which is due to either a tertiary component or periodic magnetic activity in the more massive component.  相似文献   

15.
We report the discovery of a new gravitational lens system. This object, ULAS J234311.93-005034.0, is the first to be selected by using the new UKIRT Infrared Deep Sky Survey (UKIDSS), together with the Sloan Digital Sky Survey (SDSS). The ULAS J234311.93-005034.0 system contains a quasar at redshift 0.788 which is doubly imaged, with separation 1.4 arcsec. The two quasar images have the same redshift and similar, though not identical, spectra. The lensing galaxy is detected by subtracting point spread functions from R -band images taken with the Keck telescope. The lensing galaxy can also be detected by subtracting the spectra of the A and B images, since more of the galaxy light is likely to be present in the latter. No redshift is determined from the galaxy, although the shape of its spectrum suggests a redshift of about 0.3. The object's lens status is secure, due to the identification of two objects with the same redshift together with a lensing galaxy. Our imaging suggests that the lens is found in a cluster environment, in which candidate arc-like structures, that require confirmation, are visible in the vicinity. Further discoveries of lenses from the UKIDSS survey are likely as part of this programme, due to the depth of UKIDSS and its generally good seeing conditions.  相似文献   

16.
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   

17.
Sérsic (Atlas de Galaxias Australes, Observatorio Astronómico, 1968) generalized the de Vaucouleurs law which follows the projected (observed) one dimensional radial profile of elliptical galaxies closely and Dehnen (Mon. Not. R. Astron. Soc. 265:250, 1993) proposed an analytical formula of the 3-dimensional light distributions whose projected line profile resembles the de Vaucouleurs law. This paper is involved to recover the Dehnen model and generalize the model to account for galaxy elliptical shapes by means of curvilinear coordinate systems and employing a symmetry principle. The symmetry principle maps an orthogonal coordinate system to a light distribution pattern. The coordinate system for elliptical galaxy patterns turns out to be the one which is formed by the complex-plane reciprocal transformation Z=1/W. The resulting spatial (3-dimensional) light distribution is spherically symmetric and has infinite gradient at its center, which is called spherical-nucleus solution and is used to model galaxy central area. We can make changes of the coordinate system by cutting out some column areas of its definition domain, the areas containing the galaxy center. The resulting spatial (3-dimensional) light distributions are axisymmetric or triaxial and have zero gradient at the center, which are called elliptical-shape solutions and are used to model global elliptical patterns. The two types of logarithmic light distributions are added together to model full elliptical galaxy patterns. The model is a generalization of the Dehnen model. One of the elliptical-shape solutions permits realistic numerical calculation and is fitted to all R-band elliptical images from Frei et al. (Astron. J. 111:174, 1996) galaxy sample. The fitting is satisfactory. This suggests that elliptical galaxy patterns can be represented in terms of a few basic parameters.  相似文献   

18.
We present our 1984 radial velocity observations of the W UNa system SW Lac. These give a new spectroscopic mass ratio qsp = 1.255 ±0.011. A joint solution of the velocity and light curves give the following revised absolute parameters: M1 = 0.78 M, M2 = 0.96M, R1 = 0.91R, and R2 = 1.00 R. Based on our new results, together with a detailed review of the period changes, probable mass transfer, mass loss, spot activity and other physical properties of SW Lac are discussed.  相似文献   

19.
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   

20.
We discuss implementation of light time effects in a general binary star program that solves for third body orbit parameters and binary star parameters together. The program combines radial velocities and light curves within a coherent analysis and can use data that are very unevenly distributed over time. By analyzing whole curves, the program has access to more information than only from eclipse timings. Results for λ Tau and VV Ori are shown.  相似文献   

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