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1.
High-resolution (0.1-Å) spectra of the 6815-Å band of methane are presented for Jupiter, Saturn, Uranus, and Neptune. Spectra for Uranus, Neptune, and the equatorial region of Saturn were acquired with the SPIFI (W. H. Smith, T. R. Hicks, and J. P. Born (1978). Proceedings of the 4th International Colloquium on Astrophysics, Triest, July 3–7, 1978. pp. 593–599) at the 2.2-m telescope of the Mauna Kea Observatory during May and June 1980. Additional spectra were obtained for Jupiter and the northern temperate and polar regions of Saturn in December 1980 and January 1981 from Kitt Peak National Observatory's McMath Solar Telescope. The spectra show a dichotomy in strength of methane absorption between Jupiter-Saturn and Uranus-Neptune. A simple model analysis, based on homogeneous scattering models, is unable to resolve whether this dichotomy is due to an actual increase in the methane mixing ratio with solar distance or to the temperature dependence of line strengths and absorption pathlengths in these atmospheres. If the rotational quantum number for the prominent 6818.9-Å feature is J < 4, then significant aerosol extinction must exist within the visibly accessible portion of Uranus' atmosphere for the methane mixing ratio to be greater than the solar value.  相似文献   

2.
From the data on bright stars of different spectral and luminosity classes from the 13-color photometry catalog, the selective extinction of light by the interstellar dust has been studied. The stars from the 1000-pc vicinity of the Sun were investigated. In the optical spectral range, the interstellar extinction curves show systematic deviations from the “λ?1” law, which allows one to sort them into three types. The observed curves of the interstellar dust extinction were compared with the theoretical curves calculated from the reflectance spectra of the asteroids under the approximation of the Rayleigh particles. The calculated extinction curves for the surface material of D-type asteroids and the Tagish Lake carbonaceous chondrite agree rather well with the observed curves of the interstellar extinction of the first type.  相似文献   

3.
Efforts are made to understand the timing behaviors (e.g., the jumps in the projected pulsar semimajor axis at the periastron passages) observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are suggested to orbit around the Be star, which may gravitationally perturb the (probably low mass) pulsar when it passes through periastron. An accretion disk should exist outside the pulsar's light cylinder, which creates a spindown torque on the pulsar due to the propeller effect. The observed negative braking index and the discrepant timing residuals close to periastron could be related to the existence of a disk with a varying accretion rate. A speculation is presented that the accretion rate may increase on a long timescale in order to explain the negative braking index.  相似文献   

4.
The absolute energy distributions of the cepheid Gem at several phases of the light cycle have been given. By matching these with suitable model atmospheres, the effective temperatures of the star at these phases have been determined. The radius and effective gravity variations as well as the mass have been derived.  相似文献   

5.
The appearance of features with cusp points on the diagrams of changes in the coordinates of the Earth’s instantaneous pole (polhodes) is considered as the result of mapping onto the plane of its displacement over the surface during the Earth’s rotational-translational motion. The results of qualitative and quantitative analyses of the data on the coordinates of the Earth’s instantaneous pole are discussed. The basic principles of the theory of Whitney singularities and their application for explaining the bifurcations of the equilibrium positions for the Zeeman catastrophe machine (Arnold 1990) are used in the analyses.  相似文献   

6.
From the characteristic actions (s), we can derive various relations between the basic characteristic quantities of objects and the fundamental constants in known physical laws. The main physical processes which lead to the formation of objects should be included in some such reletions through the fundamental constants. The problem of the origin of galaxies has been considered on the basis of the theory of actions (s). It has been shown that in addition to gravitational effect, the dissipation process of the adiabatic density perturbations arising from the Thomson scattering in the early universe is a crucial process in forming galaxies; and if the Hubble constant has a valueH 0 50 km s–1 Mpc–1, the protogalaxies might be formed just before recombination.  相似文献   

7.
The chemical classification of IRAS 17515-2407 has been debated for a long time. Up to now there are two contenders, oxygen-rich or carbon-rich. We believe that IRAS 17515-2407 is an oxygen-rich source: because (ⅰ) it shows the silicate self-absorbed emission; (ⅱ) in the near infrared-IRAS diagram it is located in the oxygen-rich object region and (ⅲ) particularly, it has detected SiO maser emission.  相似文献   

8.
We present observations of Ceres over the 2.2-4.0 μm region taken using the SpeX instrument on the NASA IRTF in 2005. The observations cover Ceres’ entire longitude range and show evidence for a relatively uniform surface in terms of Ceres’ composition, however there is a subtle but consistently shallower band depth over longitudes associated with bright regions in HST maps, suggesting those areas are slightly less carbonate- and brucite-rich. We also find Ceres’ beaming parameter, a measure of its thermal properties, to have changed with its viewing aspect.  相似文献   

9.
When cosmic bodies of asteroidal and cometary origin, with a size from 20 to approximately 100 m, enter dense atmospheric layers, they are destroyed with a large probability under the action of aerodynamic forces and decelerated with the transfer of their energy to the air at heights from 20–30 to several kilometers. The forming shock wave reaches the Earth’s surface and can cause considerable damage at great distances from the entry path similar to the action of a high-altitude explosion. We have performed a numerical simulation of the disruption (with allowance for evaporation of fragments) and deceleration of meteoroids having the aforesaid dimensions and entering the Earth’s atmosphere at different angles and determined the height of the equivalent explosion point generating the same shock wave as the fall of a cosmic body with the given parameters. It turns out that this height does not depend on the velocity of the body and is approximately equal to the height at which this velocity is reduced by half. The obtained results were successfully approximated by a simple analytical formula allowing one to easily determine the height of an equivalent explosion depending on the dimensions of the body, its density, and angle of entry into the atmosphere. A comparison of the obtained results with well-known approximate analytical (pancake) models is presented and an application of the obtained formula to specific events, in particular, to the fall of the Chelyabinsk meteorite on February 15, 2013, and Tunguska event of 1908, is discussed.  相似文献   

10.
Stimulated by the recent discovery of PSR J1833-1034 in SNR G21.5-0.9 and its age parameters presented by two groups of discovery, we demonstrate that the PSR J1833-1034 was born 2053 years ago from a supernova explosion, the BC 48 guest star observed in the Western Han (Early Han) Dynasty by ancient Chinese. Based on a detailed analysis of the Chinese ancient record of the BC 48 guest star and the new detected physical parameters of PSR J1833-1034, agreements on the visual position, age and distance between PSR J1833-1034 and the BC 48 guest star are obtained. The initial period P0 of PSR J1833-1034 is now derived from its historical and current observed data without any other extra assumption on P0 itself, except that the factor PP is a constant in its evolution until now.  相似文献   

11.
Since the original suggestion by Gillett et al. (1969) it has generally been assumed that the region of partial transparency near 5 μm in Jupiter's atmosphere (the 5-μm window) is bounded by the v4 NH3 at 6.1 μm and the v3 CH4 band at 3.3 μm. New measurements of Jupiter and of laboratory phosphine (PH3) samples show that PH3 is a significant contributor to the continuum opacity in the window and in fact defines its short-wavelength limit. This has important implications for the use of 5-mu;m observations as a means to probe the deep atmospheric structure of Jupiter. The abundance of PH3 which results from a comparison of Jovian and laboratory spectra is about 3 to 5 cm-am. This is five to eight times less than that found by Larson et al. [Astrophys. J. (1977) 211, 972–979] in the same spectral region, but is in good agreement with the result of Tokunaga et al. [Astrophys. J. (1979) 232, 603–615] from 10-μm observations.  相似文献   

12.
It is shown that variations in 6300 Å airglow intensities can, under certain assumptions, be simply related to ?0F2 and its time derivative. In deriving the relationship it is not necessary to assume that the concentration of the neutral atmosphere remains constant and so the relationship is useful on occasions when changes in the neutral atmosphere do occur making it difficult to obtain agreement between observed and calculated 6300 Å intensities; An example is given of a night in which a post-midnight enhancement occurred in the airglow and for which the observations could not be reproduced using a neutral atmosphere constant with time. It is shown that the airglow variations can be explained in terms of the variations of f0F2, implying that the airglow is due to recombination and that, during the night, changes occurred in the concentrations of the constituents of the neutral atmosphere.  相似文献   

13.
The effect of the Earth??s compression on the physical libration of the Moon is studied using a new vector method. The moment of gravitational forces exerted on the Moon by the oblate Earth is derived considering second order harmonics. The terms in the expression for this moment are arranged according to their order of magnitude. The contribution due to a spherically symmetric Earth proves to be greater by a factor of 1.34 × 106 than a typical term allowing for the oblateness. A linearized Euler system of equations to describe the Moon??s rotation with allowance for external gravitational forces is given. A full solution of the differential equation describing the Moon??s libration in longitude is derived. This solution includes both arbitrary and forced oscillation harmonics that we studied earlier (perturbations due to a spherically symmetric Earth and the Sun) and new harmonics due to the Earth??s compression. We posed and solved the problem of spinorbital motion considering the orientation of the Earth??s rotation axis with regard to the axes of inertia of the Moon when it is at a random point in its orbit. The rotation axes of the Earth and the Moon are shown to become coplanar with each other when the orbiting Moon has an ecliptic longitude of L ? = 90° or L ? = 270°. The famous Cassini??s laws describing the motion of the Moon are supplemented by the rule for coplanarity when proper rotations in the Earth-Moon system are taken into account. When we consider the effect of the Earth??s compression on the Moon??s libration in longitude, a harmonic with an amplitude of 0.03?? and period of T 8 = 9.300 Julian years appears. This amplitude exceeds the most noticeable harmonic due to the Sun by a factor of nearly 2.7. The effect of the Earth??s compression on the variation in spin angular velocity of the Moon proves to be negligible.  相似文献   

14.
Based on the undisturbed, finite thickness disk gravitational potential, we carried out 3-D Monte Carlo simulations of normal pulsars. We find that their scale height evolves in a similar way for different velocity dispersions (σv): it first increases linearly with time, reaches a peak, then gradually decreases, and finally approaches a stable asymptotic value. The initial velocity dispersion has a very large influence on the scale height. The time evolution of the scale height is studied. When the magnetic decay age is used as the time variable, the observed scale height has a similar trend as the simulated results in the linear stage, from which we derive velocity dispersions in the range 70- 178km s-1, which are near the statistical result of 90 - 270km s-1 for 92 pulsars with known transverse velocities. If the characteristic age is used as the time variable, then the observed and theoretical curves roughly agree for t > 108 yr only if σv < 25km s-1.  相似文献   

15.
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   

16.
Nesis  A.  Hammer  R.  Roth  M.  Schleicher  H.  Soltau  D.  Staiger  J. 《Solar physics》2001,200(1-2):11-22
The emergence and evolution of large granules shows thegranular dynamics particularly well. We therefore investigate the time dependence of the convective flows within a regular and an exploding granule. The observational material for this study was taken at the center of the solar disk with the German VTT in Izaña (Tenerife, Spain) during an observing campaign in the year 1994. It consists of series of spectrograms of high spatial resolution, which were digitized and processed with wavelet techniques. Among other features, our data show the dynamical portrait of a regular and an exploding granule. We can follow their temporal evolution over more than 12 min. Using absorption lines of different strength we are able to see the dynamical change of both granules at several heights within the first 200 km above 5000=1. The observations reveal significant changes of the convective flow of both granules over time as well as over height, which are discussed in detail.  相似文献   

17.
In this work we investigate the variations of the Earth’s rotation in the interval of periods from 2 to 8 years using the longest available observational series obtained both by means of astrometry and space geodesy. We found an abrupt change of the variation pattern in the middle of the 1980s, when classical ground-based astrometric facilities for studying the Earth Rotation Parameters (ERP) were replaced with space geodesy methods. Variations with a 6-year periodicity and ∼0.2-ms amplitude practically disappeared (space geodesy instruments did not detect these variations right from the start), but the 2- to 4-year periodicities increased in amplitude and began to dominate in this frequency range under consideration. In this study, we analyze some possible excitation sources and possible causes of the change in the variability pattern.  相似文献   

18.
The remnants of two gamma-ray bursts, GRB 030329 and GRB 041227, have been resolved by Very Long Baseline Interferometry observations. The radio counterparts were observed to expand with time. These observations provide an important way to test the dynamics of the standard fireball model. We show that the observed size evolution of these two events cannot be explained by a simple jet model, rather, it can be satisfactorily explained by the two-component jet model. It strongly hints that gamma-ray burst ejecta may have complicated structures.  相似文献   

19.
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   

20.
A new way of probing the harge-scale structure of the universe is proposed.Space is partitioned into cells the shape of rhombic dodecahedron.The cells are labelled “filled“ or “empty“ according as they contain galaxies or not ,the cell size is so chosen as to have narly equal numbers of filled and empty cells for the given galaxy sample.Two observables on each cell are definable:the number of ist like neighbors,n1,and a two-suffixed topological type τ,the suffixes being the numbers of its like and unlike neighbor-groups.The frequency distributions of n1 and τ in the observed set of filled(empty)cells are then considered as indicators of the morphology of the set,The method is applied to the CfA catalogue of galaxies as an illustration.Despite its limited size,the data offers evidence 1) that the empty cells are more stongly clustered than the filled cells,and 2) theat the filled cells,but not the empty cells,have a tendency to occur in sheets,Further directions of development both in theory and application are indicated.  相似文献   

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