排序方式： 共有7条查询结果，搜索用时 15 毫秒
1
1.
We study the center-limb (CL) variation of the average profiles of four Ca i lines near 6500 and compare these observations with synthetic data obtained from several line formation models having different thermal structures, line parameters, LTE and non-LTE conditions, and micro and macroturbulence values, to assess the formation characteristics of our Ca i lines in the solar photosphere.Comparison of numerical results with observations indicates that non-LTE is indispensable to fit the CL variation of the central residual intensity for the line 6493, and anisotropic microturbulence is indispensable to improve the CL behavior of the equivalent widths for all lines. The Ca i line analysis favors a cool photospheric model, but this cannot be disentangled clearly from the effects of non-LTE and small-scale velocity fields on the grounds of the present line formation models. 相似文献
2.
We report detailed comparisons between theoretical and empirical eigenfunctions of velocity and intensity for the 5-min modes in the photosphere. The comparison process is accomplished by obtaining synthetic profiles of the Fei 5434 Å line in the presence of waveforms given by dynamical calculations and then applying a common procedure of reduction both to the observed and to the synthetic data. For the velocity waveforms, our results show a general agreement between theory and observations together with some systematic differences; in particular the theory systematically underestimates the observations in the low photosphere. These systematic differences are stressed by the intensity results since both the computed amplitudes and phases appear to be wrong in the deeper layers. 相似文献
3.
We study the effects of both the solar granulation and short-period oscillations on the solar profile of the Ki 7699 resonance line and its center-to-limb variations.The granular model we used is that of Nelson (1978). The wave field is obtained by adding two 30 s acoustic waves with opposite horizontal wavenumbers to allow for the center-to-limb calculations.We find that the broadening and strengthening produced by our dynamical models do not fill the gap existing between the observations and the values computed in a static atmosphere. Then, either the granular model has to be revised (in particular its r.m.s. velocities are too low) or other types of motions, like gravity waves, have to be accounted for.The upper part of the mean bisectors is affected by granulation and the lower part by waves. With some qualification concerning the data used for comparison, a satisfactory fit of the observed center-to-limb variations of the mean bisectors is obtained when both dynamical models are included and the granular velocities are increased by a factor 1.5.Currently NAS/NRC Research Associate, on leave from the Universita' di Napoli.Operated by the Association of Universities for Research in Astronomy Inc., under contract with the National Science Foundation. Partial support for the NSO is provided by the USAF under a Memorandum of understanding with the NSF. 相似文献
4.
B. De Vivo L.G. Closs A. Lima R. Marmolino V. Perrone 《Journal of Geochemical Exploration》1984,21(1-3)
A governmental regional drainage survey assessed the mineral potential of Calabria in 1974. The Calabria area of southern Italy is a mineralized region in which Penninic and Austro-Alpine nappes, comprising ophiolites, metasedimentary rocks (phyllites, paragneiss, granulites, amphibolites) and granitic and granodiorite plutons, are overthrusting carbonate Apenninic nappes. Pre-Alpine stratabound and vein-type base-metal sulfide mineralization predominate, tectonically redistributed during the Alpine orogeny.A total of 5518 samples of the original 6999 active stream sediments from an area of 10,000 km2 were analyzed by X-ray fluorescence and atomic absorption for Cu, Pb, Zn, Hg, Fe, Mn, As, W, Mo, Sn, and Be on the minus 180 μm fraction. Follow-up investigation of a 39-km2 area around Bivongi-Ferdinandea using 760 soil samples analyzed for Fe, Mn, Zn, Cu, Pb, K, Mo, and Au, investigated molybdenite and chalcopyrite occurrences associated with granodiorite.A five-factor R-mode factor analysis reflected geological and mineralization features in the reconnaissance data. Factor 1 (Fe-Mn-Cu-Zn) is related to the Fe and Mn distribution in the stream sediments. Factor 2 (Be-Sn) reflects presence of pegmatites within metamorphic and magmatic rocks. Factor 5 (Mo) is essentially a single-element factor. Factor 4 (As-Pb-Zn-Hg-Cu) reflects mineralization. Factor 3 (W-Ba) does not cluster in association with any specific lithological unit. Significant metal associations, recognized from R-mode factor analysis, were used as independent variables and regressed against the original metal concentration of each sample. Residuals of multiple regression analysis, differentiated features representing mineralization from those related either to lithologic or geochemical parameters. New prospecting targets were identified and areas of known mineral occurrences were evident in the distinction of residuals.R-mode factor analysis of data from the follow-up investigation identified three factors. Factor 2 (Mo-K) reflects Mo mineralization and associated hydrothermally altered areas but does not suggest additional target areas. 相似文献
5.
We examine the effects of acoustic-gravity waves with long and short periods on the solar profile of the K i7699 line using a dynamic model of line formation.First we studied the kinetic equilibrium of the K i atoms in a static atmosphere confirming, with up-to-date atomic data and atmospheric model, that a good fit of the resonance line 7699 is possible only when non-LTE effects are accounted for.Then the static non-LTE line source function and lower-level population are used as input data for calculating the line formation in the presence of waves.The time behaviour of the synthetic profiles corresponding to 300 s and 30 s waves is extensively discussed. The characteristic redshift induced by the 30 s wave is explained within the framework of the S-S line formation model. Long-period waves yield an anticorrelation between the asymmetry at different residual intensities and the line core shift, as observed. The short-period waves with velocity amplitude of about 100 m s–1 (at the base of the photosphere) produce a mean bisector whose lower part has a slope in agreement with the observed one. The efficiency of waves to produce macro and microturbulence is also discussed.Currently NAS/NRC Senior Research Associate at Sacramento Peak Obs., New Mexico, U.S.A. 相似文献
6.
C. Marmolino 《Solar physics》1987,112(2):211-226
Unresolved motions, or microturbulence, play a very important role in determining the Doppler width of the line-absorption coefficient. The concept of microturbulence was introduced because observed solar and stellar lines are broader than is explicable within the framework of other line-broadening mechanisms. By constructing a curve-of-growth in the presence of a dynamical model for simple acoustic and gravity waves, this paper evaluates the errors introduced by the use of kinematic models for line-broadening (microturbulence) into the determinations of non-thermal velocity fields and element abundances. Distinct differences between gravity and acoustic waves are apparent in the trend of the line asymmetry with the excitation potential as well as in the magnitude of the errors introduced by the temperature and pressure variations associated with the velocity field.NAS/NRC Research Associate, on leave from the Universita' di Napoli.Operated by the Association of Universities for Research in Astronomy Inc., under contract with the National Science Foundation. Partial support for NSO is provided by the USAF under a Memorandum of Understanding with the NSF. 相似文献
7.
The broadening and shift parameters for a number of Fei lines perturbed by atomic hydrogen are computed using the interatomic potential due to Hindmarsh et al. (1967, 1970). It is also shown that the rms radius and the effective radius of the radiating atom, which determine the force constants in the interatomic potential, can be simply related each other, depending on the orbital quantum number of the atomic level.Currently NAS/NRC Research Associate, on leave from the Università di Napoli.Operated by the Association of Universities for Research in Astronomy Inc., under contract with the National Science Foundation. Partial support for the NSO is provided by the USAF under a Memorandum of Understanding with the NSF. 相似文献
1