共查询到20条相似文献，搜索用时 359 毫秒
1.
Michael Bauer 《Astrophysics and Space Science》2005,296(1-4):255-260
A method is presented to include irradiation effects in the modeling of over-contact binaries. The Roche potential is numerically
modified in a way to account for mechanical effects of the mutual irradiation of the two binary components. The efficiency
of radiative interaction is parametrized by means of the fraction of radiative over gravitational forces for each component
of the binary. The modified Roche geometry is implemented as binary model in an eclipse light curve solution code, which is
based on the general Wilson–Devinney scheme. As an example the method is applied to the early-type over-contact system V606
Cen. 相似文献
2.
Photometric solutions of four new discovered W UMa-type binaries were carried out for the first time by using the 2003 version
of the W-D program. It is discovered that all of the four systems are over-contact binaries. Two binaries, GSC 0804-0118 and
GSC 2936-0478, are of A-subtype, while two other binaries, GSC 1848-1264 and GSC 0619-0232, are of W-subtype. From our solutions,
the fundamental orbital and physical parameters were determined. For GSC 0619-0232 and GSC 2936-0478, the asymmetries of the
light curves (i.e., the O'Connell effect) were explained by the presence of dark spots on the more massive components. Our
photometric results reveal that GSC 0619-0232 is an important and interesting system. It is a W-type over-contact binary with
a low mass ratio of q = 0.100 and a high over-contact degree of f = 93.4%, which suggests that GSC 0619-0232 may be evolved into a single rapid-rotating star. 相似文献
3.
Š. Parimucha T. Pribulla M. Vaňko P. Dubovský L. Hambálek 《Astrophysics and Space Science》2008,313(4):419-423
Photometric analysis of BVR
C
light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11)
days. Photometric parameters are determined as well. The analysis yielded to conclusion that system is an over-contact binary
of W UMa type with components not in thermal contact. The light curves from 2005 show the presence of a spot on the surface
of one of the components, while light curves from 2006 are not affected by maculation. 相似文献
4.
We present photometric analysis of 8 short-period eclipsing binaries discovered and observed at Astronomical Observatory at Kolonica Saddle between 2007 and 2010 with different instruments. We determined their orbital periods and performed photometric analysis of their light curves. We found that 3 systems are detached binaries, 4 systems are over-contact binaries of W UMa type and one system is semi-detached with the secondary component filling its Roche lobe. Light curves of 2 systems exhibit asymmetries, explained by spot(s) on the surface of the components. 相似文献
5.
Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008
with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509
photomultiplier. We used these data to obtain the light curves and calculate the newtimes of minimum light in each filter
and plot the O-C diagram of ER ORI. Using theWilson’s computer code with the help of an auxiliary computer program to improve
the optimizations, the light curve analyses were carried out to find out the photometric elements of the system. 相似文献
6.
《New Astronomy》2017
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. 相似文献
7.
From the photometric and spectroscopic data on AA UMa obtained by us in 1987 and 1986 and using the Wilson-Devinney program, we made a simultaneous solution. We found mass-ratio q = 1. 8157 ± 0.0099, M1 = 0.85 M, M2 = 1. 55 M , A = 3.39 R , R1 = 1.50 R , and degree of over-contact f = 0.15 ± 0.01. Adding six minimum times obtained by us to the literature, a new epoch formula is derived: Min.I(J.D.Hel) = 2 446 885.1119+0.468 125 83 E. 相似文献
8.
J.R. Barnes A. Collier Cameron D.J. James D. Steeghs 《Monthly notices of the Royal Astronomical Society》2001,326(3):1057-1066
We present two images of intermediate and low axial inclination G dwarfs (AP 149 and AP 193) in the young open cluster α Persei, and compare these with previous images of intermediate and high axial inclination objects in this cluster. All stars show starspots at high latitudes, with one star exhibiting a strong polar spot. Although low-latitude features are found on all stars to some degree, the detection of spots on AP 193 is marginal. The apparent difference in starspot morphology from one object to the next is probably the result of a stellar magnetic cycle, although the exact effect on the starspot distribution throughout a cycle is unknown.
Polar spots are found in many Doppler images of rapidly rotating cool stars. In the past, their existence has been called into question, and it has been suggested that they could be the manifestations of NLTE (e.g. chromospheric filling in of line profiles) effects rather than real photospheric features. We assume the polar spots to be real photospheric features, and conclude that the flat-bottomed nature of the profile shape can be attributed to photospheric polar spots. The degree of truncation of the profile depends not only on spot size and strength, but also on the effective foreshortening of the polar region, a function of axial inclination.
H α is in emission on AP 149 which shows a double peak at most phases. The time-series of the profile shows an s-wave pattern as the position of these peaks changes throughout the rotation cycle. We attribute this to coronal clouds located above the stellar surface in synchronous orbit. A maximum-entropy tomogram is derived revealing four distinct emission regions located near and above the corotation radius. 相似文献
Polar spots are found in many Doppler images of rapidly rotating cool stars. In the past, their existence has been called into question, and it has been suggested that they could be the manifestations of NLTE (e.g. chromospheric filling in of line profiles) effects rather than real photospheric features. We assume the polar spots to be real photospheric features, and conclude that the flat-bottomed nature of the profile shape can be attributed to photospheric polar spots. The degree of truncation of the profile depends not only on spot size and strength, but also on the effective foreshortening of the polar region, a function of axial inclination.
H α is in emission on AP 149 which shows a double peak at most phases. The time-series of the profile shows an s-wave pattern as the position of these peaks changes throughout the rotation cycle. We attribute this to coronal clouds located above the stellar surface in synchronous orbit. A maximum-entropy tomogram is derived revealing four distinct emission regions located near and above the corotation radius. 相似文献
9.
Buhalqem Nizamdin Ali Esamdin Zhi-Yong LiuNa Wang Cheng-Shi Zhao 《Chinese Astronomy and Astrophysics》2011,35(1):37
Using the 25m radio telescope of the Urumqi Observatory, the strong single pulses of the pulsar PSR J0034-0721 were observed at 1.54 GHz on 6th Aug. 2007. With the technique of single-pulse detection, 116 single pulses with the signal-to-noise ratios of RSN≥5 were detected from the observed data of 1 h. At 1.54 GHz, the signal-to-noise ratios of the detected single pulses are in the range from 5 to 10.5, and the peak flux densities of these pulses are approximately 14∼29 times that of the average pulse (AP), much less than the ratios between the intensities of typical giant pulses and the intensity of AP. The cumulative distribution of the intensities of these pulses is basically a powerlaw distribution with the spectral index α = −4.3 ± 0.4. The detection rates for the pulses of RSN≥5 and RSN≥10 are 3% and 0.08%, respectively. For these pulses, the half-peak width W50 ranges from 1.6 ms to 8 ms, 3.9 ms in average. The phases of the vast majority of the strong single pulses are concentrated around the peak position of AP, but 2 strong pulses of RSN≥8.5 are detected at the phases about 33 ms earlier than the phase of the AP peak. This implies that there probably exist two emission regions of strong pulses, and this is consistent with the previously observed results at 40 MHz and 111 MHz, except that at 1.54 GHz the profile of AP exhibits only one component. 相似文献
10.
Nian-Ping Liu Yu Liu Yun-Deng Shen Xue-Fei Zhang Wen-Da Cao Jean Arnaud 《Chinese Astronomy and Astrophysics》2011,35(4):428
A modern aureole photometer (AP) was developed for the site survey inWest China, in preparation for the installation of future large solar equipments. The performance of this new AP was tested in preliminary observations, and a lot of sky brightness data were accumulated at a few sites in Yunnan Province. The result of data analysis shows that the aureole near the noon time on Jiaozi Snow Mountain is as low as a few millionths of the intensity at the solar disk center, indicating the low internal stray light level of our instrument. The internal stray light of the AP comes mainly from two parts: the edge diffraction of the ferrule for fixing the ND4 filter in the front end of the telescope tube, causing the stray light distributed in the inner region of the field of view, and the edge diffractions of the diaphragms placed inside the telescope tube, causing the stray light distributed in the outer region of the field of view. In order to suppress the stray light of the latter part, the experiment to change the aperture size of an additional diaphragm was performed. The result shows that the stray light in the outer region of the field of view can be effectively suppressed by reducing properly the aperture size of the diaphragm. 相似文献
11.
《New Astronomy》2016
We present new photometric observations covering eight minima times for the eclipsing binary GSC 1042-2191. The light curves in colors were analyzed by using WD-code for the system parameters. Eight minima times were obtained from the new observations. The system is found a low mass ratio (q = 0.148), A-type over-contact binary with a fill out parameter of f = 65.01 ± 12.18%. The preliminary absolute dimensions (M1= 1.26 ± 0.06 M⊙, M2 = 0.18 ± 0.06 M⊙, R1 = 1.54 ± 0.20 R⊙, R2 = 0.69 ± 0.01 R⊙, =3.30 ± 0.30 L⊙ and = 0.59 ± 0.20 L⊙) indicate the very much oversized and over-luminous secondary component, by assuming the present luminosity of the secondary is its main sequence luminosity, we predict the original mass is about 0.8 M⊙, this means the present secondary could be transferred and/or lost 77% of its original mass and only its core is left. 相似文献
12.
Short time-scale photometric properties of eight faint cataclysmic variable (CV) stars are presented. Nova Carinae 1895 (RS Car) has a photometric modulation at 1.977 h that could be either an orbital or a superhump period. Nova Carinae 1948 (V365 Car) shows flickering, but any orbital modulation has a period in excess of 6 h. The nova-like variable and X-ray source V436 Car has an orbital modulation at P orb = 4.207 h , no detectable period near 2.67 h (which had previously given it a possible intermediate polar classification), and dwarf nova oscillations (DNOs) at ∼40 s. Nova Crucis 1936 (AP Cru) has a double-humped ellipsoidal modulation at P orb = 5.12 h and a stable modulation at 1837 s characteristic of an intermediate polar. Nova Chamaeleontis 1953 (RR Cha) is an eclipsing system with P orb = 3.362 h , but at times shows negative superhumps at 3.271 h and positive superhumps at 3.466 h. In addition it has a stable period at 1950 s, characteristic of an intermediate polar. BI Ori is a dwarf nova that we observed at quiescence and outburst without detecting any orbital modulation. CM Phe is a nova-like variable for which we confirm the value of P orb = 6.454 h found by Hoard, Wachter & Kim-Quijano . We have identified the remnant of Nova Sagittarii 1931 (V522 Sgr) with a flickering source ∼2.2 mag fainter than the previously proposed candidate (which we find to be non-variable). 相似文献
13.
14.
A. Sáiz R. Domínguez-Tenreiro P.B. Tissera S. Courteau 《Monthly notices of the Royal Astronomical Society》2001,325(1):119-132
We present results from a careful and detailed analysis of the structural and dynamical properties of a sample of 29 disc-like objects identified at z =0 in three AP3M–SPH fully consistent cosmological simulations. These simulations are realizations of a CDM hierarchical model, in which an inefficient Schmidt-law-like algorithm to model the stellar formation process has been implemented. We focus on properties that can be constrained with available data from observations of spiral galaxies, namely the bulge and disc structural parameters and the rotation curves. Comparison with data from Broeils, de Jong and Courteau gives satisfactory agreement, in contrast with previous findings using other codes. This suggests that the stellar formation implementation we have used has succeeded in forming compact bulges that stabilize disc-like structures in the violent phases of their assembly, while in the quiescent phases the gas has cooled and collapsed in accord with the Fall & Efstathiou standard model of disc formation. 相似文献
15.
16.
17.
Stability of the planar full 2-body problem 总被引：1，自引：0，他引：1
D. J. Scheeres 《Celestial Mechanics and Dynamical Astronomy》2009,104(1-2):103-128
The stability of the Full Two-Body Problem is studied in the case where both bodies are non-spherical, but are restricted to planar motion. The mutual potential is expanded up to second order in the mass moments, yielding a highly symmetric yet non-trivial dynamical system. For this system we identify all relative equilibria and determine their stability properties, with an emphasis on finding the energetically stable relative equilibria and conditions for Hill stability of the system. The energetically stable relative equilibria always correspond to the classical “gravity gradient” configuration with the long ends of the two bodies pointed at each other, however there always exists a second equilibrium in this configuration at a closer separation that is unstable. For our model system we precisely map out the relations between these different configurations at a given value of angular momentum. This analysis identifies the fundamental physical constraints and limitations that exist on such systems, and has immediate applications to the stability of asteroid systems that are fissioned due to a rapid spin rate. Specifically, we find that all contact binary asteroids which are spun to fission will initially lie in an unstable dynamical state and can always re-impact. If the total system energy is positive, the fissioned system can disrupt directly from this relative equilibrium, while if it is negative the system is bound together. 相似文献
18.
19.
An analysis was carried out of the secular period variation of four WU Ma type stars (AW UMa, AP Leo, AG Vir and AH Vir) using
some newly determined times of minima as well as others reported in the literature. It was found that two stars show period
increases, one a period decrease and the remaining shows no variation in period.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
L. N. Berdnikov A. Yu. Kniazev I. A. Usenko V. V. Kovtyukh V. V. Kravtsov 《Astronomy Letters》2010,36(7):490-497
We present the results obtained by analyzing 20 spectra of six bright Cepheids taken with the 1.9-m telescope at the South
African Astronomical Observatory. The chemical composition and atmospheric parameters have been determined for XX Sgr, AP
Sgr, RV Sco, RY Sco, V482 Sco, and V636 Sco. 相似文献