首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 906 毫秒
1.
Long-term BV RI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.  相似文献   

2.
İ. Bulut 《New Astronomy》2009,14(7):604-606
The apsidal motion analysis of the eccentric eclipsing binaries: V397 Cep, V493 Car and BW Aqr have been presented. The method described by Lacy (1992) [Lacy, C.H S., 1992. AJ 104, 2213] has been used for the apsidal motion analysis. The apsidal motion periods have been found to be 174.2 ± 1.4, 277.3 ± 21.3 and 7195 ± 174 years for V397 Cep, V493 Car and BW Aqr, respectively.  相似文献   

3.
CCD multi-band light curves of the neglected eclipsing binaries V405 Cep, V948 Her, KR Mon and UZ Sge were obtained and analysed using the Wilson–Devinney code. New geometric and absolute parameters were derived and used to determine their current evolutionary state. V405 Cep, V948 Her and KR Mon are detached systems with their components in almost the same evolutionary stage. UZ Sge is a classical Algol system with a tertiary companion around it. Moreover, since the systems V405 Cep, V948 Her and UZ Sge contain an early type component, their light curves were examined for possible pulsation behaviour.  相似文献   

4.
Orbital period changes of the eclipsing binaries GO Cyg and GW Cep are explained by the light-time effect for the first time. New minima of the eclipsing binary AR Aur improve the predicted light-time orbit. The light-time orbit with the quadratic ephemeris of the binary matches the new observations of V505 Sgr better than the linear one. As the light-time effect fits in corresponding O − C diagrams of all four systems have been reaching extreme values, the observations of minima times in forthcoming years are highly desirable.  相似文献   

5.
Results from photographic and CCD photometric observations of the pre-main sequence star V 350 Cep are presented. A continued gradual rise of brightness resembling the light curves of the FUOR type stars is observed. A search in the WFPDB was made to find old photographic observations of V 350 Cep.  相似文献   

6.
We present the results of our photometric (V RI) and spectroscopic observations of the young variable star V730 Cep (MisV1147) classified by Uemura et al. (2004) as a Herbig Be star. Our photometry confirms the conclusion of the above authors that this star has a complex pattern of variability including periodic or quasi-periodic brightness variations with a period of about 14 days and deep Algol-like minima typical for UX Ori stars. Our spectroscopy shows that the classification of V730 Cep as a Herbig Be star is wrong. Actually, this star has a much lower temperature and belongs to the family of T Tauri stars. This allows us to explain the nature of the unusual photometric activity of V730 Cep based on a combination of two well-known models of variable circumstellar extinction applied to young stars: AA Tau- and UX Oritype variability. It follows from our observations that the color tracks on the V ?(V ?I) color–magnitude diagram for these models slightly differ: the AA Tau-type variability of circumstellar extinction is caused by larger grains than the UX Ori-type variability. Such a difference can be due to an increase in the characteristic sizes of circumstellar dust as the star is approached and has a simple explanation: small dust grains evaporate faster than large ones.  相似文献   

7.
  相似文献   

8.
Results from UBVRI optical photometric observations of the pre-main sequence star V350 Cep during the period 2004-2014 are presented.The star was discovered in 1977 due to its remarkable increase in brightness by more than 5 mag(R).In previous studies,V350 Cep was considered to be a potential FUor or EXor eruptive variable.Our data suggest that during the period of observations the star maintains its maximum brightness with low amplitude photometric variations.Our conclusion is that V350 Cep was probably an intermediate object between FUors and EXors,similar to V1647 0ri.  相似文献   

9.
The first photometric analysis of V811 Cep was carried out.The first complete light curves of V,R and I bands are given.The analysis was carried out by the Wilson-Devinney(W-D) program,and the results show that V811 Cep is a median-contact binary(f=33.9(±4.9) %) with a mass ratio of 0.285.It is a W-subtype contact binary,that is,the component with less mass is hotter than the component with more mass,and the light curves are asymmetric(O' Connell effect),which can be explained by the existence of a hot spot on the component with less mass.The orbital inclination is i=88.3°,indicating that it is a totally eclipsing binary,so the parameters obtained are reliable.Through the O-C analyzing,it is found that the orbital period decreases at the rate of ■=-3.90(±0.06) × 10~(-7)d yr~(-1),which indicates that the mass transfer occurs from the more massive component to the less massive one.  相似文献   

10.
  相似文献   

11.
V0842 Cep is a W UMa-type binary star that has been neglected since its discovery.We analysed the VR_cI_c light curves,obtained by the 1 m telescope at Weihai Observatory of Shandong University,using the Wilson-Devinney code.V0842 Cep was found to be a shallow contact binary system(f=8.7%) with a mass ratio of 2.281.Because its orbital inclination is greater than 80°,the photometric results are reliable.A period study is included which reveals a continually decreasing orbital period(dp/dt=1.50(±0.42)×10~(-7)d yr~(-1)).This trend could be attributed to the angular momentum loss via stellar wind.  相似文献   

12.
We present the collection of all the mid- and far-IR observations (λ=3–170 μm) of the young eruptive variable PV Cep available so far in the literature. These data allow us to confirm that flux variability is a prominent feature at mid-IR wavelength (λ=3–25 μm). Color-magnitude plots clearly indicate that the observed variability is not extinction-driven, but mainly influenced by fluctuations of the mass accretion rate. We interpret such variability as due to a hot spot created onto the stellar surface by the column of accreting matter, which heats the inner parts of the disk and determines the observed increase of the near- mid-IR luminosity. A quantitative characterization is given for both the spot itself and the additional thermal component created by it. Far-IR data (λ=60–170 μm) are consistent with the presence of a temperature stratification in a massive and quite un-evolved circumstellar disk.  相似文献   

13.
We present high resolution CS and CO maps of Cep A region made with the 45m telescope at Nobeyama. The CS map shows that a dense cloud surrounding the proto-star cluster extends in the North-South direction and is probably rotating. The bipolar molecular flow apparent in the CO maps is well-collimated along East-West direction within 0.2 pc from the proto-stars. The dense cloud is gravitationally unstable and appears to be in a contracting phase to form a cluster of massive stars.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.NRO, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a cosmic radio observing facility open for outside users.  相似文献   

14.
  相似文献   

15.
The hypothesis that W Cep has an eclipsing variability is discussed on the basis of our photometric and polarimetric observations of it from 1983–2003. Here we attempt to use our observations of W Cep to construct an average light curve, after separating out the slow variation, with the elements JDmin=2448105d+2090d. A strong variability is found from period to period at phases of 0.1–0.3 that may be caused by a variable flow of matter between the components. __________ Translated from Astrofizika, Vol. 49, No. 2, pp. 187–196 (May 2006).  相似文献   

16.
We are studying the young clusters Tr37 and NGC7160 in the Cep OB2 region as part of a program to understand the evolution of accretion disks at the ages of disk dissipation and planet formation. Here, we present the first identifications of low mass (spectral types K-M) members of the clusters and study the presence and characteristics of their accretion disks, finding evidences of disk evolution. Using optical photometry and spectroscopy, we have identified ～70 members in Tr37 and ～20 in NGC7160, confirming age estimates of 3 and 10 Myr respectively. Accretion rates are ～10?8 M ⊙yr?1 in Tr37. We have not found any accreting members in NGC7160, suggesting that disk accretion generally ends before the age of 10 Myr, which is consistent with the results from other populations.  相似文献   

17.
The photomectic observations of EP Cep, from Kaluzny and shara (1987), were analyzed by the Wilson and Devinney method. The appropriate value of the mass ratio of this system was found after extensive searches. EP Cep has a semi-detached configuration where the lower-mass component is in contact with its respective Roche surface. The higher-mass component very nearly fills its Roche lobe. It is very close to being a critical configuration. The mass ratio of the system is about 1.292 and the inclination is 66 . ° 942. EP Cep has the characteristic of a W-type WUMa 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 (Baliunas and Guinan, 1985).  相似文献   

18.
PhotometricUBV-observations of VW Cep, a W UMa-type eclipsing binary, were made in 1971 and 1978–79. The (O-C)-diagram, with the newly determined times of minima extended, shows sudden increases and decreases in the period of VW Cep. The difference light curves (the observed light curves compared with a reference light curve) show some correlations with the sudden change of the period. In particular, the difference between the two light curves from 1971 and 1978 is also presented. The system may be in marginal contact, and as such is possibly unstable with respect to mass exchange between its components. In accordance with the variation of (O-C)-values the mass transfer between the both components is discussed. The difference between the depths of the two minima shows irregular changes, while that between the heights of the two maxima shows a long term variation on which irregular fluctuations are superimposed.  相似文献   

19.
We present X-ray emission characteristics of the massive O-type stars DH Cep and HD 97434 using archival XMM-Newton observations. There is no convincing evidence for short-term variability in the X-ray intensity during the observations. However, the analysis of their spectra reveals X-ray structure being consistent with two-temperature plasma model. The hydrogen column densities derived from X-ray spectra of DH Cep and HD 97434 are in agreement with the reddening measurements for their corresponding host clusters NGC 7380 and Trumpler 18, indicating that the absorption by stellar wind is negligible. The X-ray emission from these hot stars is interpreted in terms of the standard instability-driven wind-shock model.  相似文献   

20.
The light curve andU, B andV observations of the system XY Cep have been presented. Photoelectric and absolute elements of the system have been determined. It is a semi-detached system.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号