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1.
An estimate of the period of the rotation of the line of apsides of the double-star system Phe is obtained by representing the density function as a product of a normal Gaussian distribution and an associated Legendre polynomial
.The asymptotic behaviour of this function coincides with the results obtained by Zeldovichet al. (1981).The period of motion of the line of apsides of Phe (about 63 years) obtained in this way comes close to the period determined by an empirical formula for
of Batten (1973). 相似文献
2.
Cong Huang Gang Zhao Hua-Wei Zhang Yu-Qin Chen Department of Astronomy Peking University Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(6):619-626
Using high signal-to-noise ratio spectra of extrasolar planet-hosting stars, we obtained the atmospheric parameters, accurate metallicities and the differential abundance for 15 elements (C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Ni and Ba). In a search for possible signatures of metal-rich material accreting onto the parent stars, we found that , for a given element, there is no significant trend of increasing [X/H] with increasing condensation temperature Tc. In our sample of planet-harboring stars, the volatile and refractory elements behave similarly, and we can not confirm if there exists any significant dependence on the condensation temperature Tc. 相似文献
3.
We present X-ray spectral analyses of the low-mass X-ray binary Cir X-1 dur- ing X-ray dips,using the Rossi X-ray Timing Explorer(RXTE)data.Each dip was divided into several segments,and the spectrum of each segment was fitted with a three-component blackbody model,in which the first two components are affected by partial covering and the third one is unaffected.A Gaussian emission line is also included in the spectral model to represent the Fe Kαline at~6.4 keV.The fitted temperatures of the two partially covered components are about 2 keV and 1 keV,while the uncovered component has a temperature of~0.5-0.6 keV.The equivalent blackbody emission radius of the hottest component is the smallest and that of the coolest component is the largest.During the dips the fluxes of the two hot components are linearly correlated,while that of the third component does not show any significant variation.The Fe line flux remains constant,within the errors,during the short dips.However,during the long dips the line flux varies significantly and is positively correlated with the fluxes of the two hot components.These results suggest:(1)that the tem- perature of the X-ray emitting region decreases with radius,(2)that the Fe Kαline emitting region is close to the hot continuum emitting region,and(3)that the size of the Fe line emit- ting region is larger than that of the obscuring matter causing the short dips but smaller than the region of that causing the long dips. 相似文献
4.
Zhan-Kui Huang Xin-Ji Wu Department of Astronomy Peking University Beijing Chinese Academy of Sciences-Peking University Joint Beijing Astrophysics Center Beijing National Astronomical Observatories Urumqi Astronomical Observatory Chinese Academic of Science Urumqi 《中国天文和天体物理学报》2003,3(2):166-174
The initial period of a pulsar is an important factor in our understanding of the formation of neutron stars and of the nature of the equation of state of neutron star matter.Up to now this quantity can only be obtained for a few pulsars for which accurate age and braking index are known.Based on the theory of the offcenter dipole emission,in which pulsars obtain theiry high velocities depending on the initial periods,we calculate the initial period using the proper motion data,Because the orbital velocity of the progenitor and asymmetric kick in the supernova explosion may also contribute to the observed velocity of the pusar,the derived values of initial periods are lower limits.For normal pulsars,the initial periods are in the range of 0.6~2.6ms.For the millisecond pulsars,the initial periods are comparable to their current periods,and the ratio between the initial period and the current period increases with the decrease of the current period.For PSR B1937 21 with the shortest period of 1.56ms,the ratio is 0.77. 相似文献
5.
We summarize studies of helical properties of solar magnetic fields such as current helicity and twist of magnetic fields in solar active regions (ARs), that are observational tracers of the alpha-effect in the solar convective zone (SCZ). Information on their spatial distribution is obtained by analysis of systematic mag-netographic observations of active regions taken at Huairou Solar Observing Station of National Astronomical Observatories of Chinese Academy of Sciences. The main property is that the tracers of the alpha-effect are antisymmetric about the solar equator. Identifying longitudinal migration of active regions with their individual rotation rates and taking into account the internal differential rotation law within the SCZ known from helioseismology, we deduce the distribution of the effect over depth. We have found evidence that the alpha-effect changes its value and sign near the bottom of the SCZ, and this is in accord with the theoretical studies and numerical simulations. We discuss 相似文献
6.
E. S. Dmitrienko 《Astrophysics and Space Science》2011,335(1):149-153
We present the analysis of the morphology of the light curves of WZ Sge based on simultaneous multicolour highspeed photometry
durings the superoutburst in 2001. Observations started around the middle of the main superoutburst and continued for several
nights in each of the subsequent phases of its evolution. For the first time for WZ Sge in a superoutburst a significant difference
between the morphology of the U and BVRI light curves was detected. This is interpreted as a consequence of a substantial
distinction of the structure and radiation between the inner and outer parts of the accretion disc. Using the space observatory
WSO-UV for UV monitoring of the WZ Sge-stars throughout the entire superoutburst cycle one would have an opportunity to explore
innermost regions of the accretion discs in these systems, which is important for understanding the physics of accretion processes
and the nature of their activity. 相似文献
7.
Photometry of Persei was obtained during ingress and egress of its 1989 eclipse and analyzed using a simple geometrical model. The estimated depths of eclipse are 0.62, 0.43, and 0.23 mag inU, B, andV, respectively, which imply that all but 17% of the A-type secondary is covered by the G-giant primary at minimum light. When combined with observations from the 1984 eclipse, the data yield a photometric period of 1515.869±0.059 days. 相似文献
8.
Ying-He Zhao Qiu-He Peng Lan Wang Department of Astronomy Nanjing University Nanjing Joint Astrophysics Center of Chinese Academy of Science-Peking University Beijing The Open Laboratory of Cosmic Ray High Energy Astrophysics Chinese Academy of Sciences National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(1):51-60
We propose a method to determine the thickness of non-edge-on disk galaxies from their observed structure of spiral arms, based on the solution of the truly three-dimensional Poisson‘s equation for a logarithmic disturbance of density and under the condition where the self-consistency of the density wave theory is no longer valid. From their measured number of arms, pitch angle and location of the innermost point of the spiral arms, we derive and present the thicknesses of 34 spiral galaxies. 相似文献
9.
V. G. Gorbatskii 《Astrophysics》2000,43(1):1-5
A model is proposed for the formation of clouds of the La forest. Earlier calculations have shown that the UV emission from hot stars must play an important role in the reionization
of the pregalactic medium (PGM). The formation of galaxies therefore occurred simultaneously with PGM ionization, and the
reionization process was nonlinear. With allowance for this fact, the Gunn-Peterson effect, and the fact that galaxies exist
at z ≈ 5, which follows from observations, we can conclude that galaxies began to form earlier, perhaps at z ≥ 10. The observed
presence of heavy elements in La -forest clouds is evidence that these clouds were formed later than galaxies — from interstellar clouds ejected by galactic
wind. The next generation of galaxies might have resulted from an increase in the masses of La -forest clouds due to their merging.
Translated from Astrofizika, Vol. 43, No. 1, pp. 5-12, January–March, 2000. 相似文献
10.
《紫金山天文台台刊》1996,(2)
Four plates,photographed on March 17,1986 by Oversea Observation Team of CAS at Mount John Observatory,show the rays of Comey Halley.We scanned and measured three of them by the PDS micro-densitometer of PMO.The folding speed (towards the tail's spine) of the rays and the motion of some matter in the tail were obtained. 相似文献
11.
Infrared Characteristics of Associated Sources of Water Masers 总被引:2,自引:0,他引:2
Jarken Esimbek 《中国天文和天体物理学报》2005,5(6):587-594
We present an analysis of the infrared properties of 1417 water masers collected from the literature published by December 2004. The associated infrared sources of the water masers were identified with IRAS and MSX (Midcourse Space Experiment) catalogues. There are 1252 water masers associated with IRAS sources within 1', which include 700 interstellar and 552 stellar sources. For 382 sources, the IRAS counterpart identification and the maser classification are new. We found the colors of the interstellar maser sources are much redder than those of the stellar ones at IRAS wavelength bands; 99% of the interstellar maser sources are above black body line, while 95% of the stellar masers are below. The distribution difference of the two kinds of masers shown in the color-color diagram is due to their different optical depths and temperature distributions of dust regions. There are 743 water masers with MSX counterparts, of which 552 are interstellar masers and 191 are stellar masers. MSX colors of the associated sources of water masers are here analyzed for the first time. The color differences among the MSX bands are small and the interstellar masers are redder than the stellar masers. There is a correlation between the intensity of the stellar water maser emission and that of the 12μm and 25μm emissions, while there is no correlation between the water maser emission and the 8 μm emission. The infrared intensity increases with increasing wavelength for the interstellar masers, while it is the opposite for stellar masers. These results may provide clues for the pumping of water maser and for the properties of the two kinds of maser emission regions. 相似文献
12.
Bao-An Yao Chun-Sheng Zhang Qing LinShanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Purple Mountain Observatory Chinese Academy of Sciences Nanjing 《中国天文和天体物理学报》2004,4(4):397-410
A performance study of several CCD cameras of the Chinese Joint Laboratory of Optical Astronomy (CJLOA) is presented. The main results are: 1) We propose a modified classical method to analyse the linearity of CCD cameras. This method is more sensitive and accurate as well as more intuitive, especially in measuring around the 0.1%-0.2% range of nonlinearity. 2) To illustrate the advantage of the method, the linearity performance of the CCD cameras at CJLOA has been measured and analysed. 3) For the CCD systems tested, there is no unique formula to represent the correlation over the entire CCD frame between the deviation from linearity and the pixel value, i.e., different pixel has different correction even though their pixel values are the same. 4) For the BFOSC (BAO Faint Object Spectrograph Camera) Loral CCD camera and the Tek CCD camera at the 1.56-m reflector, blooming (bleeding) happens long before saturation, and we suspect whether it could have resulted from the charge transfer efficiency (CTE) n 相似文献
13.
14.
A. Kh. Rzaev 《Astrophysical Bulletin》2008,63(1):23-33
The temporal variations of the radial velocity and profile of the Hα line in the spectrum of α Cyg are analyzed based on 240 CCD spectra taken with the coude spectrograph attached to the 2-m telescope of Shamaha Astrophysical Observatory of the National Academy of Sciences of Azerbaijan in 1998–2000. The results obtained are inconsistent with the conclusion made by the Heidelberg group concerning the behavior of the variability of the Hα-line profile [1]. The observed pattern of radial-velocity variations is due to nonradial pulsations and differs for the blue and red halves of the absorption profile. The pulsation parameters differ for different levels of residual intensity for both halves of the absorption profile. The amplitude and period increase from the core toward the wing of the line for the red half of the absorption profile, and, on the contrary, decrease toward the line wing for the blue half of the profile. Absorption features are observed on the blue half of the absorption profile. Their emergence and disappearance, as well as minor migrations are indicative of the clumpy structure of the stellar envelope. The similarity of the variability behavior of the absorption and emission profiles indicates that the latter too owe their variability to nonradial pulsations. Thus the variability of the stellar wind in its formation regions is partly due to the nonradial pulsations of the underlying layers of the atmosphere. On the whole, the variability of the position and photometric parameters of the absorption and emission components of the profile is indicative of the nonstationary nature and asymmetric shape of the stellar wind. 相似文献
15.
The physical state of optically thin, primordial gas in intergalactic space at redshift about Z=2.5 is re-examined, assuming the gas is in ionzation and thermal equilibrium by the integrated UV flux from QSOs. For densities in the range 10–5–10–2 cm–3, the structure of the gas can be well described by an isothermal polytrope of infinite index. The L absorbing clouds observed in the spectra of distant QSOs may arise in such self-gravitating intergalactic clouds. Some properties of the clouds are discussed with reference to recent observations and equilibrium models.This work is partially supported by CNSF. 相似文献
16.
The Influence of Mass-Loss on the Orbit of Comet 总被引:1,自引:0,他引:1
《紫金山天文台台刊》1996,(2)
Using the Jeans problem and the Fermi problem of two bodies with variable masses,the influence of solar and cometary mass-loss on the orbit of comet SL9 is discussed in this paper.It is shown that solar and cometary mass-loss both will cause the secular and periodic terms in the semimajor axis a of comet SL9.The influence of solar massloss on the orbit of comet SL9 is very small and it may be omitted.But the influence of mass-loss of comet SL9 itself on its orbit is large and it may cause the secular variation in a to be about 104 km every year.The cometary mass-loss will obviously influence the time and place of the comet SL9 crashing into Jupiter.Therefore it should be considered on the orbit calculation and prediction of cornet SL9. 相似文献
17.
V. M. S. Carrasco J. M. Vaquero M. C. Gallego A. Lourenço T. Barata J. M. Fernandes 《Solar physics》2018,293(11):153
A sunspot catalogue was published by the Coimbra Astronomical Observatory (Portugal), which is now called the Geophysical and Astronomical Observatory of the University of Coimbra, for the period 1929?–?1941. We digitalised data included in that catalogue and provide a machine-readable version. We show the reconstructions for the (total and hemispheric) sunspot number index and sunspot area according to this catalogue and compare it with the sunspot number index (version 2) and the Balmaceda sunspot area series (Balmaceda et al. in J. Geophys. Res.114, A07104, 2009). Moreover, we also compared the Coimbra catalogue with records made at the Royal Greenwich Observatory. The results demonstrate that the historical catalogue compiled by the Coimbra Astronomical Observatory contains reliable sunspot data and can therefore be considered for studies about solar activity. 相似文献
18.
We present a study of the β Cephei instability strip based on a sample of 49 stars of this type.After deriving their effective temperatures and luminosities from their observed(B-V),(U-B) colors and parallaxes we find their positions in the HR diagram to be mostly confined to the main sequence,and their masses to lie between 7 M and 30 M.Their distribution on the HR diagram matches well with our previous theoretical instability strip which has an upper bound in the luminosity and rather tight boundaries in the effective temperature. 相似文献
19.
Maria Pia Di Mauro Jørgen Christensen-Dalsgaard Lucio Paternò 《Astrophysics and Space Science》2003,284(1):229-232
We investigate properties of the internal structure of HR2021, better known as Hydri, a G2 IV subgiant with mass close to solar and for which observations by Bedding et al. (2001) have shown the presence of solar-like oscillations.We have computed models of Hydri,based on updated global parameters,and compared the computed frequencies for the models with the observed oscillation spectrum. 相似文献
20.
P. A. Sturrock 《Solar physics》2009,260(2):245-250
The histogram formed from published capture-rate measurements for the GALLEX solar-neutrino experiment is bimodal, showing two distinct peaks. However, the histogram formed from published measurements derived from the similar Gallium Neutrino Observatory (GNO) experiment is unimodal, showing only one peak. Nevertheless, the two experiments differ in run durations: GALLEX runs are either three weeks or four weeks (approximately) in duration, whereas GNO runs are all about four weeks in duration. When we form three-week and four-week subsets of the GALLEX data, we find that the relevant histograms are unimodal. The upper peak arises mainly from the three-week runs, and the lower peak from the four-week runs. The four-week subset of the GALLEX dataset is found to be similar to the GNO dataset. A recent re-analysis of GALLEX data leads to a unimodal histogram. 相似文献