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1.
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
2.
For nine published high-resolution QSO spectra a correlation analysis of their L forest lines has been performed. The two-point correlation functions show some quasi-periodic structure of magnitude ||0.3. Their characteristic separation along the line-of-sight amounts to s
0=3×10–3 or to s
0=5×10–3 for =1 and 0.2, respectively. Especially the distribution of nearest neighbouring line positions in two close QSO pairs allows for the interpretation that the absorption clouds lie in sheet-like structures as predicted by the pancake theory. The correlation data contain some hints on metal absorbers within the forest of unidentified lines. 相似文献
3.
Bian Yulin 《Astrophysics and Space Science》1991,180(1):113-131
The distribution of the absorption lines in the L forest of QSOs is re-examined in relation to both absorption and emission redshifts by analyzing a sample consisting of 20 QSO L forests.On the one hand, the -value in the relationN(z
abs)=N
0(1+z
abs) is re-estimated by applying the maximum likelihood (ML) method to all the L forests in our sample as a whole as well as to the forests for individual QSOs. The global estimated is 2.20±0.28 and both the quasars with highest and lowestz
em do not individually have a significant effect on it. A non-parametric test on the estimate of from individual QSOs shows that there is no significant difference between the numbers of positive and negative -values. This does not, therefore, favour the idea that for individual QSOsN(z
abs) decreases with increasingz
abs.On the other hand, the possible correlation between the absorption line density and the emission redshift of the QSO itself, which was found by Bianet al. (1986, 1988) and re-discovered independently by Tytler (1987), is shown once again not only by the largerz
em QSOs having larger mean density, but more importantly, at a rather high confidence level, by the fact that, at the same values ofz
abs, QSOs with largerz
em possess a greater number of L absorption lines.A discussion of the inverse effect suggests that it is still hard to say whether this effect really exists. 相似文献
4.
5.
V. F. Gopka A. V. Yushchenko V. A. Yushchenko I. V. Panov Ch. Kim 《Kinematics and Physics of Celestial Bodies》2008,24(2):89-98
Absorption lines of some actinides, namely, actinium (Z = 89), protactinium (91), neptunium (93), plutonium (94), americium (95), curium (96), berkelium (97), californium (98), and einsteinium (99), were identified in the spectrum of one of the most peculiar main-sequence stars HD 101065 (Przybylski’s star). In the identification we used a high-resolution spectrum (R = 80 000) acquired at the 8.2-m ESO telescope. 相似文献
6.
We present the results of modelling of the radio spectrum evolution and dispersion measure variations of PSR B1259–63, a pulsar in a binary system with Be star LS 2883.We base our model on a hypothesis that the observed variations of the spectrum are caused by thermal free-free absorption occurring in the pulsar surroundings. We reproduce the observed pulsar spectral shapes in order to examine the influence of the stellar wind of LS 2883 and the equatorial disc on the pulsar’s radiation.The simulations of the pulsar’s radio emission and its consequent free-free absorption give us an insight into the impact of stellar wind and equatorial disc of LS 2883 has on the shapes of PSR B1259–63 radio spectra, providing an evidence for the connection between gigahertz-peaked spectra phenomenon and the close environment of the pulsar. Additionally, we supplement our model with an external absorbing medium, which results in a good agreement between simulated and observational data. 相似文献
7.
Cody Schultz Brendan A. Anzures Ralph E. Milliken Taki Hiroi Kevin Robertson 《Meteoritics & planetary science》2023,58(2):170-194
H2O and OH are readily detected in hydrated minerals in CM chondrites via reflectance spectroscopy due to their characteristic vibration absorptions at infrared wavelengths. Previous spectroscopic work on bulk powdered CM chondrites has shown that spectral parameters, like the wavelength position of the “3 μm absorption feature,” vary systematically with the extent to which the samples have been aqueously altered. However, it is yet unclear how these spectral features may vary across an intact meteorite chip when measured at spatial scales smaller than that of the individual components of the meteorite. Here, we explore the spatial variability of this spectral feature and others on intact CM2 chips which, unlike powders, retain their petrologic and textural characteristics. We also model the modal mineralogy of the bulk meteorite powders and correlate this with key spectral features, demonstrating that microscope Fourier transform infrared spectroscopic mapping provides a powerful, rapid, and non-destructive technique for assessing compositional diversity and variations in water–rock interactions in chondritic planetary materials. In all CM2 chondrites studied here, we find that variations in the position, shape, and strength of the 3 μm absorption feature reveal a single chondrite can exhibit as much spectral variation as the entire suite of CM2 chondrites. The observed variations in the position and shape of the 3 μm feature within individual CM2 chondrite chips suggest a range of alteration products (e.g., Mg-rich to Fe-rich phyllosilicates) are present and record sub-mm scale variations in the amount and/or chemistry of the altering fluids. The samples having experienced the most progressive aqueous alteration show the least amount of variability in features like the 3 μm absorption band minimum position, whereas the least altered samples exhibit the most variability. We also find that the bulk spectral signatures in the least altered samples appear to be biased toward the spectral signatures of clasts versus matrix. By extension, asteroid reflectance spectra exhibiting 3 μm absorption features consistent with those measured here may be interpreted in a similar framework in which the spectrum of what may appear to be the least altered asteroids represents an average that belies the true diversity of mineralogy and chemistry of the body. 相似文献
8.
Rodolfo Batista Negri Antonio Fernando Bertachini de Almeida Prado Alexander Sukhanov 《Celestial Mechanics and Dynamical Astronomy》2017,129(3):269-284
The swing-by maneuver is a technique used to change the energy of a spacecraft by using a close approach in a celestial body. This procedure was used many times in real missions. Usually, the first approach to design this type of mission is based on the “patched-conics” model, which splits the maneuver into three “two-body dynamics.” This approach causes an error in the estimation of the energy variations, which depends on the geometry of the maneuver and the system of primaries considered. Therefore, the goal of the present paper is to study the errors caused by this approximation. The comparison of the results are made with the trajectories obtained using the more realistic restricted three-body problem, assumed here to be the “real values” for the maneuver. The results shown here describe the effects of each parameter involved in the swing-by. Some examples using bodies in the solar system are used in this part of the paper. The study is then generalized to cover different mass parameters, and its influence is analyzed to give an idea of the amount of the error expected for a given system of primaries. The results presented here may help in estimating errors in the preliminary mission analysis using the “patched-conics” approach. 相似文献
9.
G. S. Kurbasova 《Bulletin of the Crimean Astrophysical Observatory》2010,106(1):82-86
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
10.
Jun-Liang Zhao Li Chen Zhong-Liang Zu Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 《中国天文和天体物理学报》2006,6(3):287-296
Absolute proper motions and radial velocities of 202 open clusters in the solar neighborhood, which can be used as tracers of the Galactic disk, are used to investigate the kinematics of the Galaxy in the solar vicinity, including the mean heliocentric velocity components (u_1,u_2,u_3) of the open cluster system, the characteristic velocity dispersions (σ_1,σ_2,σ_3), Oort constants (A, B) and the large-scale radial motion parameters (C,D) of the Galaxy. The results derived from the observational data of proper motions and radial velocities of a subgroup of 117 thin disk young open clusters by means of a maximum likelihood algorithm are: (u_1,u2,u3) = (-16.1±1.0, -7.9±1.4,-10.4±1.5) kms~(-1), (σ_1,σ_2,σ_3) = (17.0 ±0.7,12.2±0.9,8.0±1.3) kms~(-1),(A,B) = (14.8±1.0,-13.0±2.7) kms~(-1) kpc~(-1) ,and(C,D) = (1.5±0.7,-1.2±1.5) kms~(-1) kpc~(-1) . A discussion on the results and comparisons with what was obtained by other authors is given. 相似文献
11.
Shuang Gao Bi-Wei Jiang Yong-Heng Zhao Department of Astronomy Beijing Normal University Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2007,7(1):111-119
1 INTRODUCTION The globular cluster (GC hereafter), as the oldest star group in the universe, has been a target that astro- physics has paid close attention to all the time. The near-field (Galaxy) cosmology makes contacts with the far-field cosmology by … 相似文献
12.
Y. P. Varshni 《Astrophysics and Space Science》1988,149(2):197-215
The emission and absorption lines (3716–4290) in the spectrum of the quasar 0237–233 are identified within the framework of the PLS model. The available evidence indicates that it is a helium star. Similarities between the spectral properties of 0237–233 and the star Upsilon Sagittarii are pointed out. Predictions are made for the absorption-line spectrum which falls outside 3716–4290 and also for an expected discontinuity at 2600. 相似文献
13.
Ying-Chun Wei Xin-Ji Wu Qiu-He Peng Na Wang Jin Zhang National Astronomical Observatories/Urumqi Observatory Chinese Academy of Sciences Urumqi Department of Astronomy Peking University Beijing Department of Astronomy Nanjing University Nanjing 《中国天文和天体物理学报》2005,5(6):610-618
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
14.
To correctly determine the relative contribution of aerosol to the scattering properties of a gas–aerosol medium in the continuum, we propose a method that allows more reliable values of the imaginary part of the refractive index n i to be obtained for Jupiter’s atmosphere in the short-wavelength spectral range. We considered the measurement data on the spectral values of the geometric albedo of Jupiter acquired in 1993 and used the model of homogeneous spherical aerosol particles. The obtained values of n i are 0.00378, 0.00309, 0.00254, 0.00175, 0.00123, 0.00084, 0.00064, 0.00045, 0.00031, 0.00033, 0.00013, and 0.00008 at wavelengths λ = 320, 350, 375, 400, 420, 450, 470, 500, 520, 550, 606, and 631 nm, respectively. 相似文献
15.
Liu Yong-Zhen 《Astrophysics and Space Science》1989,152(2):191-201
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
16.
17.
Jia-Long Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,(3)
Taking the 13-point smoothed monthly sunspot number, Ri, and the deviation of the 13 associated monthly sunspot numbers from the smoothed one, D_i, as a number-pair describing the global level of sunspot activity, the evolution of the level is statistically studied for the period from the month which is just 48 months before the minimum to the minimum in the descending phase, using the observed data of Solar Cycles 10 to 22. Our results show (1) for 46 months (94%) of the studied 49 months it is found that for a given month, the distribution of the 13 pairs which come from the 13 solar cycles on a log Ri-D_i plane may be fitted by a straight line with a correlation coefficient larger than the critical one at confidence level α= 5%, and for 36 months (73%) the fitting is even better, for α= 1%;(2) time variations of these two parameters and their correlations in the studied period can be described respectively by functions of time, whose main trends may be expressed by a linear or simple curvilinear function; (3) the evolutionary path of the level of sunspot activity may be represented by a logarithmic function as log R_i=0.704 In D_i-0.291. 相似文献
18.
N. G. Mykhailytska 《Kinematics and Physics of Celestial Bodies》2010,26(6):302-312
In the spectral region λλ = 610.25−610.57 nm of the roAp star HD 101065, we performed the identification of the rare-earth
element absorption lines absent from the atomic spectral line databases VALD and DREAM. The identified lines were used for
calculating the synthetic spectra of the roAp stars HD 137949, HD 134214, and HD 24712. The upper limit of the identified
line estimates was determined. The rotation/pulsation parameter νsini and magnetic field modulus were determined using the lines Nd III 669.083 nm and Ca I 616.217 nm. The element abundance in
the roAp stars HD 134214 and HD 24712 was determined for the first time using Nd III lines. Calculations were carried out
with the help of the code SynthM developed by S.A. Khan. 相似文献
19.
Some results of observations of the spectrum of the spectroscopic-binary Ap star CrB in the region of the lithium line Li I 6708Å are presented. The observations were made at the Crimean Astrophysical Observatory over the period 1993–1995 with the coudé spectrograph equipped with a CCD camera on the 2.6-m telescope. Several factors which can affect the behavior of the lithium blend are examined: stellar rotation, magnetic field, isotopic shift, the binary system, and blending by unidentified elements. The principal result of this work is the detection of variability of the lithium blend Li I 6708Å over the period of rotation of the star. The variations of the radial velocity Vr, and the FWHM of the lithium blend are reported here for the first time. They indicate either a nonuniform distribution of lithium or a nonuniform distribution of conditions for excitation of the lithium resonance doublet in the complex structure of the strong surface magnetic field. Similar variations are also shown by the lines of the rare-earth elements Gd II 6702.10 Å, Gd II + Ce II 6704.3Å, and Ce II + Fe I 6706.0 Å.Translated fromAstrofizika, Vol. 39, No. 1, pp. 19–30, January–March, 1996. 相似文献
20.
S. G. Sergeev 《Astrophysics and Space Science》1992,197(1):77-86
A great number of spectra of the Seyfert galaxy nucleus NGC 4151 were obtained in the Crimean Astrophysical Observatory in 1988–1990 using the CCD. Significant variation in continuum intensity and broad H line profile were noted. Differences between individual spectra and the spectrum taken as a standard were calculated to study this variability. It was noted that different parts of the profile are varying in different ways. Smaller changes are located at far-away regions of the wings and at the low positive velocities of the profile. Lower variations in the red part of H profile near the center of the line are interpreted by the delay effect in an expanded shell. Since the evidences for accretion in a BIR are clisting (including NGC 4151) then either the BLR is a complex system where both inflow and low velocities outflow are observed or the outflow must be referred to the inner NLR. Cross correlation analysis shows shorter delay for the higher velocities of the H profile and does not contradict to the outflow at low velocities (near the line center), but its confidence level is small. Lower response to the continuum changes at far away parts of the broad H wings evidences that the gas in the vicinity of the central engine is optically thin for the ionizing radiation. 相似文献