A measurement of the O₂(b¹Σ_g⁺−X³Σ_g⁻) atmospheric band and the OI(¹S) green line in the nightglow     

G. Witt  J. Stegman  B.H. Solheim  E.J. Llewellyn 《Planetary and Space Science》1979,27(4):341-350

Simultaneous measurements of the nightglow profiles of the O₂(b¹Σ_g⁺?X³Σ_g^?) A-band, the atomic oxygen green line and the OH (8?3) Meinel band are presented. The altitude profiles are used to determine both the excitation mechanisms for the oxygen emissions and the atomic oxygen altitude distribution. It is shown that the measurements are consistent with a green line excitation through the Barth mechanism and that the molecular oxygen emission is excited through oxygen recombination and the reaction between OH¹ and atomic oxygen. The derived atomic oxygen concentrations,6.2 × 10¹¹cm^?3at 98km, are consistent with the Jacchia (1971) model.  相似文献   

Astrophysically useful radiative transition parameters for?the?e¹Π–X¹Σ⁺ and ¹Σ⁺–X¹Σ⁺ systems of zirconium oxide     

R. Shanmugavel  P. Sriramachandran 《Astrophysics and Space Science》2011,332(2):257-262

The zirconium oxide (ZrO) is well known for its astrophysical importance. The radiative transition parameters that include Franck-Condon (FC) factor, r-centroid, electronic transition moments, Einstein coefficient, band oscillator strengths, radiative life time and effective vibrational temperature have been estimated for e ¹Π–X ¹Σ⁺ and ¹Σ⁺–X ¹Σ⁺ band systems of ⁹⁰ZrO molecule for the experimentally known vibrational levels using RKR potential energy curves. A reliable numerical integration method has been used to solve the radial Schr?dinger equation for the vibrational wave functions of upper and lower electronic states based on the latest available spectroscopic data and known wavelengths. The estimated radiative transition parameters are tabulated. The effective vibrational temperatures of these band systems of ⁹⁰ZrO molecule are found to be below 4200 K. Hence, the radiative transition parameters help us to ascertain the presence of ⁹⁰ZrO molecule in the interstellar medium, S stars and sunspots.  相似文献   

N₂ 2P Fluorescence from scattering of N₂2σ_g photoelectrons     

B.E. Cole  R.N. Dexter 《Planetary and Space Science》1979,27(4):313-316

N₂ 2P fluorescent intensity was monitored as a function of incident photon energy from 40 to 70 eV. A structure was seen near 52.2 eV. This feature is attributed to the scattering of photoelectrons originating from the N₂ 2σ_g molecular orbital with a binding energy of about 37.7 eV. The kinetic energy of these photoelectrons corresponds to the peak of the 2P excitation cross section at 14.5 eV.  相似文献   

Five-dimensional Brans–Dicke M¹×R³×S¹ cosmology with?chameleon scalar field     

Ahmad Rami El-Nabulsi 《Astrophysics and Space Science》2010,327(1):111-115

We investigate five-dimensional Brans–Dicke cosmology with spacetime described by the homogeneous, anisotropic and flat spacetime with the topology M ¹×R ³×S ¹ where S ¹ is taken in the form of a circle. We conjecture throughout this letter that the extra-dimension compactifies as the visible dimensions expand like b(t)≈a ⁻¹(t) and that the non-minimal coupling between the scalar field and the matter is of the form f(φ)∝ φ ². The model gives rise to a transition from a decelerated epoch to an accelerated epoch for large values of the Brans–Dicke parameter ω. The model predicts crossing of the phantom divided barrier unless the universe is governed by a growing matter field.  相似文献   

RATAN-600 7.6-cm deep sky strip surveys at the declination of the SS433 source during the 1980–1999 period. Data reduction and the catalog of radio sources in the right-ascension interval 7^h ≤ R.A. < 17^h     

N. S. Soboleva  E. K. Majorova  O. P. Zhelenkova  A. V. Temirova  N. N. Bursov 《Astrophysical Bulletin》2010,65(1):42-59

We use two independent methods to reduce the data of the surveys made with RATAN-600 radio telescope at 7.6 cm in 1988–1999 at the declination of the SS433 source. We also reprocess the data of the “Cold” survey (1980–1981). The resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and fluxes of objects identified with those of the NVSS catalog in the right-ascension interval 7 ^h ≤ R.A. < 17 ^h . We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra are based on the data from all known catalogs available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are mostly sources with fluxes smaller than 30mJy. About 65% of these sources have flat or inverse spectra (α > −0.5). We analyze the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10–15 mJy objects found in the considered right-ascension interval were already included in the decimeter-wave catalogs.  相似文献   

Theoretical interpretation of the 0.7820 μm CO₂ band and 0.8226 μm H₂O line on Venus     

James L. Regas  Lawrence P. Giver  Robert W. Boese  Jacob H. Miller 《Icarus》1975,24(1):11-18

We have analyzed the P6, P8, and P10 lines in the 0.7820 μm CO₂ band of Venus using a scattering model. Our new results compare favorably with previous results from the 1.05 μm CO₂ band. We considered nonabsorbing and absorbing clouds. We found that the anisotropic scattering mean free path for both models at the 0.2atm level is between 0.55 and 0.73km, a range close to the value of 1 km for terrestrial hazes. We used our scattering models to synthesize the 0.8226 μm H₂O line, assuming that the clouds are composed of sulfuric acid drops, and found our nonabsorbing cloud required a sulfuric acid concentration of 82% by weight, while our thicker absorbing cloud required a concentration of 89%. A comparison of the variation of optical depth with height for our cloud models with the variation reported by Prinn (1973, Science182, 1132–1134) showed that, within a factor of 2, the variation for Prinn's thinnest cloud agreed with ours. Whitehill and Hansen (1973, Icarus20, 146–152) have recently confirmed the work of Regas et al. (1973a, J. Quant. Spectry. Radiative Transfer13, 461–463) which showed that two cloud layers are not required to explain the CO₂ phase variation of Venus. Prinn's recent photochemical study of sulfuric acid clouds further supports a single, continuous cloud layer in the line formation region instead of two cloud layers with an extensive clear region between. The single layer model appears more likely because the maximum particle density in Prinn's cloud occurs in the clear region between the two layers in the models of Hunt (1972, J. Quant. Spectry. Radiative Transfer12, 405–419) and Carleton and Traub (1972, Bull. Amer. Astron. Soc.4, 362.).  相似文献   

High spectral resolution ground-based observations of Venus in the 450- to 1250-cm⁻¹ region     

Virgil G. Kunde  Rudolf A. Hanel  Lawrence W. Herath 《Icarus》1977,32(2):210-224

Ground-based observations of Venus were made with a 5-cm drive Michelson interferometer during December 1970 and December 1973. The thermal emission spectrum of the central portion of the apparent disk was recorded from 450–1250 cm^?1 with an apodized spectral resolution of 0.25 cm^?1. All statistically significant sharp line absorption features in the spectrum have been identified with gaseous CO₂. Comparison between the observed spectrum and a synthetic spectrum computed from a model atmosphere, assuming gaseous CO₂ and a sulfuric acid haze as opacity sources, indicates good agreement. A broad diffuse absorption feature associated with the sulfuric acid haze is evident in the 870- to 930 cm^?1 region. With the exception of the rotational lines of the 927-cm^?1 CO₂ band, the above feature appears as a continuum down to 0.25 cm^?1 resolution. In the 750- to 1250-cm^?1 range, the spectrum exhibits moderate thermal contrast with maximum brightness temperatures of 234–238°K occurring near 825 cm^?1. These temperatures are in general agreement with previous measurements.  相似文献   

Modeling the atmospheric limb emission of CO₂ at 4.3 μm in the terrestrial planets     

M.A. López-Valverde  M. López-Puertas  G. Gilli  P. Drossart  V. Formisano 《Planetary and Space Science》2011,59(10):988-998

The MIPAS instrument on board Envisat, in Earth orbit, the PFS and OMEGA instruments on Mars Express, and VIRTIS on board Venus Express are currently providing a dataset of limb measurements of the CO₂ atmospheric fluorescence emission at 4.3‐μm from the upper atmosphere of the three planets. These measurements represent an excellent dataset to perform comparative studies between the terrestrial planets’ upper atmospheres, and also to test our theoretical understanding of these emissions. In order to exploit these datasets, we apply a set of non-local thermodynamic equilibrium (non-LTE) models developed at the IAA/CSIC, in Granada, Spain, to a selection of data. In general, the models can explain the main spectral features of the measurements, and also the altitude and solar zenith angle variations. However, the simulations for Mars and Venus give an incorrect ratio of the emissions at two wavelengths, 4.4 and . In order to explain this deficiency, a revision of the most uncertain non-LTE energy transfer parameters has been performed. The quenching rate of ν₃ quanta of high-energy CO₂ states by CO₂ itself could reduce the model-data discrepancy if increased by a factor 2-4, still within its current uncertainty range. This factor, however, is subject to the uncertainty in the thermal structure. A number of simulations with the non-LTE models were also used to study and compare the role of radiative transfer in this spectral region in the three terrestrial planets. Sensitivity studies of density and temperature are also presented, and they permit an analysis of how the differences between the planets and between the three instruments affect their sounding capabilities.  相似文献   

An auroral enhancement of O₂λ1.27-μm emission     

Doran J. Baker  William R. Pendleton  Gerald J. Romick  Vincent B. Wickwar  Murray I. Baron 《Planetary and Space Science》1978,26(7):619-634

The ground-level zenith radiance of the atmospheric emission at λ1.27 μm was radiometrically observed to increase by a factor of approximately two with the onset of an IBC III⁺ auroral breakup above Chatanika, Alaska, on 10 March 1975. Time-resolved optical spectra clearly show that the slow component of the enhancement is associated with the (0,0) band of the infrared atmospheric system of O₂. Photometric and incoherent scatter radar data are used to define the energy-deposition profile and the absolute energy flux for the event. The magnitude of the O₂λ1.27-μm enhancement compares favourably with the predictions of an auroral excitation model which includes only secondary-electron excitation of molecular oxygen in the O₂(a¹Δ_g) source term.  相似文献   

On the interpretation of the “inverse phase effect” for CO₂ equivalent widths on Venus     

Laird P. Whitehill  James E. Hansen 《Icarus》1973,20(2):146-152

Computations of the equivalent widths of absorption lines as a function of planetary phase angle are made for a homogeneous cloud with particles having the properties (shape, refractive index, and size distribution) deduced from polarimetry of Venus. The computed equivalent widths show an “inverse phase effect” comparable to that which is observed for CO₂ lines on Venus. This result verifies a recent suggestion of Regas et al. that the existence of an inverse phase effect does not by itself imply the presence of multiple layers of scattering particles in the atmosphere of Venus.  相似文献   

Distributions of the Venus 1.27-μm O₂ airglow and rotational temperature     

S. Ohtsuki  N. Iwagami  H. Sagawa  M. Ueno  Y. Kasaba  T. Imamura  K. Yanagisawa 《Planetary and Space Science》2008,56(10):1391-1398

Imaging spectroscopic observations of the Venus 1.27-μm O₂ airglow were carried out with ground-based telescopes from 2002 to 2007. Spectral image cubes were taken with the Okayama Astrophysical Observatory/infrared imaging spectrometer (superOASIS), the Gunma Astronomical Observatory/near-infrared camera and NASA's Infrared Telescope Facility/cryogenic echelle spectrograph (CSHELL). The rotational temperature shows weak positive correlation with the airglow intensity. However, there are some regions that have almost same intensities but different temperatures. The intensities tend to decrease from the anti-solar point to the terminator besides local features. These results indicate that there are local strong downward flows superimposed on the subsolar-to-antisolar circulation.  相似文献   

Discrimination of α and β/γ interactions in a TeO₂ bolometer     

J.W. BeemanF. Bellini  L. Cardani  N. Casali  I. DafineiS. Di Domizio  F. Ferroni  F. OrioG. Pessina  S. PirroC. Tomei  M. Vignati 《Astroparticle Physics》2012,35(9):558-562

TeO₂ crystals have proven to be superb bolometers for the search of neutrinoless double beta decay in many respects. However, if used alone, they do not exhibit any feature that allows to discriminate an α energy deposit from a β/γ one. This fact limits their ability to reject the background due to natural radioactivity and eventually affects the sensitivity of the search. In this paper we show the results of a TeO₂ crystal where, in coincidence with its bolometric heat signal, also the luminescence light escaping the crystal is recorded. The results show that we are able to measure the light produced by β/γ particles, which can be explained as due to Cerenkov emission. No light is detected from α particles, allowing the rejection of this background source.  相似文献   

Calculation of the Intensity Ratio and Intrinsic Redshift Ratio of the Cerenkov Iron K_α and K_β Lines and Its Possible Application in the Study of AGNs     

Dang-bo Liu  Lei Chen  Jun-han You 《Chinese Astronomy and Astrophysics》2008

We have pointed out that, when thermal relativistic electrons with an isotropic velocity distribution move through a region of dense gas or impinge upon its surface, the Cerenkov effect will produce a particular kind of atomic or ionic emission line, which we have called the “Cerenkov line-like radiation”. This prediction for the optical wavebands has been verified by laboratory experiments. In this paper, we extend this line-like radiation theory to the X-ray waveband and give the basic formulae for calculating the intensity ratio and intrinsic redshift ratio of the Cerenkov iron K_α and K_β lines, for different ionization orders of iron. Potential application of this calculated result may be found in the study of AGNs. The recent observations of NGC3783 show that besides the iron K_α line at ∼6.4 keV, there is also a very strong iron Kβ line at ∼7.0 keV, and that the ratio of equivalent widths between the two is anomalous: EWK_α/EWK_β ≈ 3.43. It is difficult to explain this by the conventional mechanism of “photoelectric absorption-fluorescence emission”. We suggest that the mechanism of Cerenkov line-like radiation can provides a way of solving this puzzle. Besides, we expect that the calculated intrinsic redshift ratio of Cerenkov iron K_α and K_β lines could be tested in future observations. If our suggestion is further supported by observations, then our view on the physical environment around the central massive black hole of an AGN will be greatly modified: the activity becomes more energetic and violent, and the gas, much denser than previously thought.  相似文献   

On the relationship of 6300 Å airglow to parameters of the F-region of the ionosphere     

P.A. Hopgood  P.L. Dyson 《Planetary and Space Science》1978,26(1):93-98

It is shown that variations in 6300 Å airglow intensities can, under certain assumptions, be simply related to $\text{?}{}_0\text{F2}$ 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   

A Study of the [O_II]λ3727/H_α Flux Ratio of Emission Line Galaxies     

Gao Feng  Kong Xu  Lin Xuan-bin  Zhang Wei  Li Jun-rong 《Chinese Astronomy and Astrophysics》2010

With the sample of 10⁵ emission line galaxies selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4), we have investigated the relations of the [O_II]λ3727/H_α flux ratio with the dust extinction, the ionization state of interstellar gas and the metal abundance of galaxies. It is found that the dust extinction correction has a significant effect on the [O_II]λ3727/H_α flux ratio. Before and after the dust distinction correction is made, the mean [O_II]λ3727/H_α flux ratios are 0.48 and 0.89, respectively. After the dust extinction is corrected, the dispersion of the distribution of F([O_II]λ3727) as a function of F(H_α) is obviously reduced. The [O_II]λ3727/H_α flux ratio of metal-poor galaxies decreases with the increasing ionization degree of interstellar gas, but this relation does not exist in metal-rich galaxies. Besides, it is found that the [O_II]λ3727/H_α flux ratio is correlated with the metal abundance. When 12 + lg(O/H) > 8.5, the [O_II]λ3727/H_α flux ratio decreases with the increasing metal abundance; for the galaxies of 12 + lg(O/H) > 8.5, the spectral flux ratio correlates positively with the metal abundance. Finally, by using the parameters of gas ionization degree and metal abundances of galaxies, the formulae for calculating the [O_II]λ3727/H_α flux ratios of different types of galaxies are given. With the [O_II]λ3727/H_α flux ratio given by these formulae, the star formation rate can be derived by using the [O_II]λ3727-line flux, for the galaxies of the redshift z > 0.4, such as the large number of galaxies to be observed by the LAMOST telescope.  相似文献   

The Modulations of the Electromagnetic Waves near 1/2ω_cH~ in Observations of Freja     

《紫金山天文台台刊》1996,(2)

In this paper the non-linear parametric resonance is proposed to understand the reason why the observed the electromagnetic ion cyclotron waves in the auroral energization region are usually concentrate in the range close to the half value of the proton gyrofrequency [Gustafsson et at.,1990].The electromagnetic ion cyclotron waves are supposed to exist already at ωcH ,then,the non-linear parametric resonane can predict the peak at 1/2ωc H The parametric resonance is saturated by the non-linear effects and a drift of the resonance frequency is also predicted from  相似文献   

Characteristic actionsħ (s) in the structure of the universe and the problem of the origin of galaxies     

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   

Ultraviolet studies of the interstellar gas in the direction of the stars AE Aur (09.5V) andθ 2 Ori A (09.0V)     

Kâmuran Avcioğlu  Hüseyin Menteşe 《Astrophysics and Space Science》1989,151(2):227-234

We have studied high-resolution SWP spectra of AE Aur and ² Ori A, obtained from the International Ultraviolet Explorer Satellite; and derived curve of growth and column densities ofCii,Cii ^*, Alii, Siii, Siii ^*,Sii, Crii, Feii, Niii, and Znii. It has been possible to fit these ions on one empirical curve of growth with a velocity parameterb=13 km s^–1 for both stars.Based on the observations made by the International Ultraviolet Explorer (IUE), and collected at the Villafranca Satellite Tracking Station of the European Space Agency.  相似文献   

Sunspot Catalogue of the Observatory of the University of Coimbra (1929 – 1941)     

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   

Optical constants of amorphous and crystalline H₂O-ice in the near infrared from 1.1 to 2.6 μm     

R.M. Mastrapa  M.P. Bernstein  T.L. Roush  C.M. Dalle Ore 《Icarus》2008,197(1):307-320

Using new laboratory spectra, we have calculated the real and imaginary parts of the index of refraction of amorphous and crystalline H₂O-ice from 20 to 150 K in the frequency range 9000-3800 cm⁻¹ (1.1-2.6 μm) at a spectral resolution of 1 cm⁻¹. These optical constants can be used to create model spectra for comparison to spectra from Solar System objects. We also analyzed the differences between the amorphous and crystalline H₂O-ice spectra, including weakening of bands and shifting of bands to shorter wavelength in amorphous H₂O-ice spectra. We have also observed two spectrally distinct phases of amorphous H₂O-ice.  相似文献