共查询到20条相似文献，搜索用时 15 毫秒
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M.E. Van Den Ancker P.R. Wesselius A.G.G.M. Tielens L.B.F.M. Waters 《Astrophysics and Space Science》1997,255(1-2):69-75
We present SWS grating scans of pure H2 rotational lines, as well as several infrared fine-structure lines for two embedded
Young Stellar Objects, S106 IR and Cep A East. Excitation temperatures and masses were derived from the low-lying pure rotational
levels of H2 and are 490 and 740 K and 0.04 and 0.007 M⊙ for S106 and Cep A, respectively. The observations were compared
to theoretical models for PDRs and dissociative and non-dissociative shocks. The infrared spectrum of S106 IR is dominated
by PDR emission while that of Cep A East has a large shock component. We suggest that the difference between these two objects
could reflect an evolutionary trend.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
D. Lorenzetti S. Antoniucci T. Giannini A. Di Paola A. A. Arkharov V. M. Larionov 《Astrophysics and Space Science》2013,343(2):535-539
We present new near-infrared (IR) spectra (0.80–1.35 μm) of the pre-Main Sequence source PV Cep taken during a monitoring program of eruptive variables we are conducting since some years. Simultaneous photometric and spectroscopic observations are systematically carried out during outburst and quiescence periods. By correlating extinction-free parameters, such as HI recombination lines and underlying continuum, it is possible to infer on the mechanism(s) responsible for their origin. Accretion and mass loss processes have a dominant role in determining the PV Cep irregular variability of both continuum and line emission. The potentialities of the observational modality are also discussed. 相似文献
4.
The main spectral characteristics of PV Cep, a T Tau star, and of the variable nebula GM1-29 associated with it are considered. Their variations during 1976-1997, based on observations on the 6-m telescope and literature data, are described. In the period of maximum brightness (1977-1979), the star had a well-developed emission spectrum, typical of classical T Tau stars, with clearly defined P Cyg components in the H and H lines, strong Na D absorption features shifted in the blue direction, and well-defined fluorescence in Fe I emission features. After the end of the latter eruption, the star's spectrum has remained more or less in a stable state; emission lines are considerably weaker. The ejected matter continues to be observed in the form of shifted components in emission lines. There are also indications of the possible existence of a collimated jet 1.5-2 long in the star's immediate vicinity. Also clearly seen is HH215 P1 — the first HH knot in the giant jet emerging from PV Cep. At the epoch of the object's maximum brightness, there were clear signs of spectral asymmetry of the stellar envelope in the nebula's spectrum, due to the directional outflow, manifested in variation of the profiles and intensities of Balmer lines. PV Cep and GM1-29 thereby prove to be another object in which the phenomenon first noted in R Mon and NGC 2261 is observed. 相似文献
5.
Synthetic light curve solutions for the W UMa-system VW Cep have been determined by applying the most new version of Wilson
(1998)approach to B-observations of 1996 and VRI-observations of 1999. From a consideration of the possible evolution of this
system, it is found that the system is a partial eclipsing contact one, and its primary to be a nearly Main-Sequence F5 star
of mass 0.85 M
⊙ and the secondary to be a dwarf of spectral type G0 of mass 0.34 M
⊙.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Integral spectroscopy data for the nebula GM 1-29 and the source star PV Cep obtained on the 2.6-m telescope at the Byurakan
Observatory are presented. The structure and kinematics of a collimated emission outflow directed along the axis of the nebula
are studied. Changes in the radial velocity and intensity of the absorption component of the nebular Hα line are observed
and studied; these are interpreted as a result of an anisotropy in the stellar wind at distances on the order of several stellar
radii, where this absorption is formed.
__________
Translated from Astrofizika, Vol. 51, No. 3, pp. 461–468 (August 2008). 相似文献
7.
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
8.
Three color photoelectric observations of the close binary system XZ Cep at the Abastumani Astrophysical Observatory are reported.
These data cover the entire light curve and represent, up to now, the best and most extensive observations of this star. The
positions of the components of XZ Cep on a mass-log g diagram show that it is in a phase following a rapid transfer of mass.
The theoretical light curves are not fully consistent with the observed curves at phases of 0.35-0.40 and 0.6-0.9. This is
evidently because of the influence of gaseous flows in the system. The existence of circumstellar matter and gas flows at
phases of 0.7-0.9 are also confirmed by spectral data and by changes in the intrinsic polarization of XZ Cep. In addition,
a polarimetric study of the star indicates that two or more interstellar clouds with different properties lie between XZ Cep
and us. A detailed study of the photoelectric data presented here is also extremely interesting for the confirmation of the
latter idea. 相似文献
9.
J. A. Docobo V. S. Tamazian N. D. Melikian M. H. Eritsian A. A. Karapetian 《Astrophysics》2000,43(2):162-169
The results of photometric and polarimetric observations of the star Μ Cep at Byurakan Observatory are presented. Some interesting
correlations between the parameters of the star’s brightness variation and the degree of polarization of the light are obtained.
It is suggested that the recorded rapid changes in the degree of polarization may result from Μ Cep being a double star.
Translated from Astrofizika, Vol. 43, No. 2, pp. 219-228, April–June, 2000. 相似文献
10.
《天文和天体物理学研究(英文版)》2017,(2)
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
11.
Multicolor photometric and polarimetric observations of the eclipsing binary EK Cep at the Crimean Astrophysical Observatory
in 1995 and 2006–2007 are reported. Polarimetric observations were made of stars in the neighborhood of EK Cep. It is shown
that the observed linear polarization of EK Cep is determined by a variable circumstellar constituent, as well as by the interstellar
component. Various possible mechanisms for formation of the intrinsic polarization of binary stars are discussed.
Translated from Astrofizika, Vol. 52, No. 1, pp. 117–126 (February 2009). 相似文献
12.
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
13.
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
14.
D. Lorenzetti S. Antoniucci T. Giannini G. Li Causi A. Di Paola A. A. Arkharov V. M. Larionov 《Astrophysics and Space Science》2014,353(2):567-573
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
15.
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
16.
A. Niezurawska M. Szymczak A. M. S. Richards R. J. Cohen 《Astrophysics and Space Science》2005,295(1-2):37-42
Two star-forming regions Cepheus A and W75N, were searched for the 4765-MHz OH maser emission using the multi-element radio linked interferometer network (MERLIN). The excited OH emission has an arc-like structure of 40 mas in Cep A and a linear structure of size 45 mas in W75N. We also found the 1720-MHz line in Cep A and Hutawarakorn [MNRAS 330 (2002) 349] reported the 1720-MHz emission in W75N. The 1720- and 4765-MHz OH spots coincided in space within 60 mas and in velocity within 0.3 km s–1 in both targets implying that both maser transitions arise from the same region. According to the modelling by Gray [MNRAS 252 (1991) 30] the 1720/4765-MHz co-propagation requires a low density, warm environment. The masers lie at the edges of H II regions where such conditions are expected. 相似文献
17.
Young Shuk Ahn 《Astrophysics and Space Science》1992,198(1):137-148
NewUBV photoelectric observations of NY Cep were made from 1982 to 1989 with GOTO 61-cm telescope at the Yonsei University Observatory. Seven times of minimum light were obtained. An improved orbital period of 15.27566 day was determined. The light curves were analyzed using the Wilson-Devinney method. It is confirmed that NY Cep is a detached system and the absolute dimensions are also obtained. It is found that the secondary eclipse does not occur due to large eccentricity and inclination. 相似文献
18.
T. A. Polyakova 《Astrophysics》2006,49(2):164-172
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.
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Translated from Astrofizika, Vol. 49, No. 2, pp. 187–196 (May 2006). 相似文献
19.
M. T. Edalati 《Astrophysics and Space Science》1994,220(1):107-113
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
20.
俞志尧 《中国天文和天体物理学报》1996,(4)
根据文[1]中图1（a）和图1（b），分别对CepB和CepF进行成图处理，得到了它们的强度分布图和速度分段积分等高图，通过对这些强度分布图和速度分段积分等高图的分析和研究，也得到了CegheusOB3巨分子云复合体是成块的，并且这些块是没有被自引力束缚的，同时还得到了CepB和CepF的外流的动力学时标。 相似文献