共查询到20条相似文献，搜索用时 31 毫秒
1.
A diagnostic method for the determination of the vector magnetic field through the interpretation of spectropolarimetric profiles observed in solar active regions is presented. An inversion routine, that is based on the analytical solution of the radiative transfer equation for polarized radiation given by Unno and Rachkowsky, is described; the routine performs a comparison among theoretical profiles depending on eight parameters and the observed profiles by means of a non linear least square fit. The routine has been applied to the interpretation of the spectropolarimetric profiles observed on 15 September, 1980 in a sunspot with the spectropolarimeter (Stokes II) of the High Altitude Observatory, National Center for Atmospheric Research*. One of the eight parameters (the line center) gives information on the plasma motions. The significance of these motions inside the sunspot is discussed.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
2.
The response function defines the response of line profiles to a depth variation of such atmospheric parameters as velocity, magnetic field and turbulence. The properties of this function are derived and compared with the so-called contribution function.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献
3.
Richard C. Altrock Laurence J. November George W. Simon Robert W. Milkey Simon P. Worden 《Solar physics》1975,43(1):33-37
Heights of formation of lines that do not exhibit Zeeman splitting are calculated using an LTE, partial non-LTE, and full
non-LTE approach. Non-magnetic (g=0) lines are valuable for velocity investigations in quiet-Sun magnetic field regions, and a knowledge of their formation
heights is useful for obtaining three dimensional velocity profiles in these regions.
Presently at Sacramento Peak Observatory.
Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献
4.
Maps of the coronal magnetic field before and after several proton flares were examined. There are indications that large scale changes occur in both the photospheric and coronal magnetic field as a consequence of large proton flares.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
5.
High resolution KPNO magnetograph measurements of the line-of-sight component of the photospheric magnetic field over the entire dynamic range from 0 to 4000 gauss are used as the basic data for a new analysis of the photospheric and coronal magnetic field distributions. The daily magnetograph measurements collected over a solar rotation are averaged onto a 180 × 360 synoptic grid of equal-area elements. With the assumption that there are no electric currents above the photospheric level of measurement, a unique solution is determined for the global solar magnetic field. Because the solution is in terms of an expansion in spherical harmonics to principal index n = 90, the global photospheric magnetic energy distribution can be analyzed in terms of contributions of different scale-size and geometric pattern. This latter procedure is of value (1) in guiding solar dynamo theories, (2) in monitoring the persistence of the photospheric field pattern and its components, (3) in comparing synoptic magnetic data of different observatories, and (4) in estimating data quality. Different types of maps for the coronal magnetic field are constructed (1) to show the strong field at different resolutions, (2) to trace the field lines which open into interplanetary space and to locate their photospheric origins, and (3) to map in detail coronal regions above (specified) limited photospheric areas.The National Center for Atmospheric Research is sponsored by the National Science foundation.Kitt Peak National Observatory is operated by the Association of Universities for Research in Astronomy, Inc. Under contract with the National Science Foundation. 相似文献
6.
Charles W. Querfeld Raymond N. Smartt Veronique Bommier Egidio Landi Degl'innocenti Lewis L. House 《Solar physics》1985,96(2):277-292
The Stokes components of He i D3 emission in two quiescent prominences, using full spectral profile measurements, are analyzed to derive vector magnetic fields. Two independently developed schemes, based on the Hanle effect, are used for interpretation. They involve solutions of the statistical equilibrium equations for the He i D3 multiplet, including the effect of coherency and full level crossing, which predict the magnetic field dependence of the observed polarization. Derived magnetic field vector solutions for each pair of linear polarization Stokes profiles corresponding to an observational point in the prominence are, intrinsically, not uniquely determined, and a set of possible solutions is usually obtained. However, mutual consistency of these solutions with those independently predicted by the form of the circular polarized component, allow, in almost all cases, rejection of all solutions of a set except one symmetrical pair. Of such a pair, a unique solution can be determined with a high confidence level by reference to independent potential field information. Field vectors are found usually to be close to horizontal and normal to the prominence surface, but extreme exceptions are found. Field values range from 6 G to 60 G. The derived vectorfield configurations and their magnitudes are briefly discussed relative to these prominences and to different quiescent prominence models.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation. 相似文献
7.
Simultaneous observations obtained with the HAO/SPO coronal emission-line polarimeter and the new SPO emission-line coronagraph are compared. The polarimeter data are measured in the Fexiii (10747 Å) line and the coronagraph observations are recorded in the Fexiv (5303 Å) line. The polarimeter field-of-view is relatively coarse compared with the resolution limit of the coronagraph. Therefore, the observed coronal polarization cannot be related directly to the detailed loop structures that characterize the localized coronal distribution, but it is found that large-scale emission features have corresponding polarization signatures. Since the measured linear polarization vectors describe the projected magnetic field direction, as shown theoretically, it follows that the form of the large-scale coronal distribution describes corresponding magnetic field structures. Measured polarization values are consistent with those predicted theoretically. Interpretation of these data to obtain corresponding magnetic field directions suggests that the value usually accepted for iron abundance in the corona might be too large.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Operated by the Association of Universities for Research in Astronomy, Inc. under contract AST 78-17292 with the National Science Foundation. 相似文献
8.
Martin D. Altschuler Dorothy E. Trotter Gordon Newkirk Jr. Robert Howard 《Solar physics》1975,41(1):225-226
Tables of spherical harmonic coefficients for the global photospheric magnetic field between 1959 and 1974 are now available on microfilm. (These are the same coefficients which were used to construct the maps of the coronal magnetic atlas.)The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
9.
In this paper we present our results of the application of the magnetograph formula to synthetic Stokes V profiles in prominences. We investigate both the Zeeman and atomic-polarization signatures within the V profile and question why previous attempts to determine magnetic field strength, on average, were correct, even if the magnetograph formula does not apply in general.The National Center for Atmospheric Research is sponsored by the National Science FoundationSponsored by the Summer Undergraduate Program of the High Altitude Observatory 相似文献
10.
It has recently been suggested that the large scale structure of the interplanetary magnetic field can be deduced solely from solar wind speed measurements. Here it is emphasized that, in addition to speed measurements, direct measurements of the interplanetary field and indirect diagnostics such as measurements of the solar wind kinetic temperature and galactic and solar energetic particle modulations and anisotropics are required to distinguish between open and closed magnetic structures in the solar wind.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
11.
First observations of the full Stokes vector in the upper chromosphere are presented. The He I 10830 Å line, which has been shown to give reliable measurements of the line-of-sight component of the magnetic field vector, has been used for this purpose. It is shown that the difference between the appearance of chromospheric and photospheric magnetic structures observed close to the solar limb is largely due to the difference in height to which they refer and projection effects. The observations do suggest, however, that the magnetic field above sunspot penumbrae is somewhat more vertical in the chromosphere than in the photosphere.The National Optical Astronomy Obervatories are operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation 相似文献
12.
Most models of large scale solar magnetic fields assume either that the fields are potential or that they are force free. We present a new, analytic, two parameter family of magnetic fields in equilibrium with isothermal plasma in a gravitational field. We discuss these models from the viewpoint of the insight into the balance of magnetic pressure gradient, and gravitational forces that they provide. We show that substantial deviations from the potential field configuration are obtained for plasma of order unity, and we emphasize the variety of possible relationships between isobars and magnetic fieldlines.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
13.
Observations are presented which suggest that away from sunspots photospheric magnetic flux is quantized. Assuming the elemental area of a magnetic region to be 1 (arc-sec)2 the elemental field strength is 525 G.Kitt Peak National Observatory Contribution No. 501.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献
14.
Hector Socas-Navarro Valentín Martínez Pillet David Elmore Anna Pietarila Bruce W. Lites Rafael Manso Sainz 《Solar physics》2006,235(1-2):75-86
Ellerman bombs are bright emission features observed in the wings of Hα, usually in the vicinity of magnetic concentrations.
Here we show that they can also be detected in the Ca II infrared triplet lines, which are easier to interpret and therefore
allow for more detailed diagnostics. We present full Stokes observations of the 849.8 and 854.2 nm lines acquired with the
new spectro-polarimeter SPINOR. The data show no significant linear polarization at the level of 3 × 10−4. The circular polarization profiles exhibit measureable signals with a very intricate pattern of peaks. A non-LTE analysis
of the spectral profiles emerging from these features reveals the presence of strong downflows (∼10 {km s−1}) in a hot layer between the upper photosphere and the lower chromosphere.
Visiting Astronomers, National Solar Observatory, operated by the Association of Universities for Research in Astronomy, Inc.
(AURA), under cooperative agreement with the National Science Foundation.
The National Center for Atmospheric Research (NCAR) is sponsored by the National Science Foundation, USA. 相似文献
15.
Y. Nakagawa 《Solar physics》1970,12(3):419-437
A comprehensive examination of the stability of prominences is presented, and the gross behavior of prominences is considered
in terms of the stability of an optically thin plasma supported by a magnetic field against gravity, including thermal effects
on the energy balance. It is shown that (1) hydromagnetic as well as hydrodynamic waves of short wavelengths could induce
instability which leads to the formation of prominences, and (2) in quiescent prominences, the dominant factor which controls
the instability is the shear between the permeated and the supporting magnetic fields. The dependence of these instabilities
on the radiative loss and other hydromagnetic effects are discussed.
The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
16.
This paper is an exploration of the possibility that the large-scale equilibrium of plasma and magnetic fields in the solar corona is a minimum energy state. Support for this conjecture is sought by considering the simplest form of that equilibrium in a dipole solar field, as suggested by the observed structure of the corona at times of minimum solar activity. Approximate, axisymmetric solutions to the MHD equations are constructed to include both a magnetically closed, hydrostatic region and a magnetically open region where plasma flows along field lines in the form of a transonic, thermally-driven wind. Sequences of such solutions are obtained for various degrees of magnetic field opening, and the total energy of each solution is computed, including contributions from both the plasma and magnetic field. It is shown that along a sequence of increasingly closed coronal magnetic field, the total energy curve is a non-monotonic function of the parameter measuring the degree of magnetic field opening, with a minimum occurring at moderate field opening.For reasonable choices of model parameters (coronal temperature, base density, base magnetic field strength, etc.), the morphology of the minimum energy solution resembles the observed quiet, solar minimum corona. The exact location energy minimum along a given sequence depends rather sensitively on some of the adopted parameter values. It is nevertheless argued that the existence of an energy minimum along the sequences of solutions should remain a robust property of more realistic coronal wind models that incorporate the basic characteristics of the equilibrium corona- the presence of both open and closed magnetic regions.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
17.
Tyan Yeh 《Solar physics》1977,55(1):241-250
In the coronal-interplanetary space the plasma motion, in a reference frame corotating with the Sun, is aligned with the magnetic field. Just like the solar wind, which is the supersonically expanding flow along open field lines, the flow along closed field lines is mainly driven by the pressure gradient. The flow in the regions of closed field lines is subsonic, being determined by the conditions at the two footpoints of the magnetic flux tube.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
18.
The topological character of a new type of solution representing a force-free magnetic field near bipolar sunspots is examined. It is shown that some of the observed topological features of chromospheric fibrils and filaments in H can be interpreted in terms of the configuration of the magnetic lines of force of the present solution. In particular, by the examples considered the observed twisted S-shape topology of lower lying fibrils and the orientation of prominences (higher filaments) associated with sunspots are successfully reproduced.Visiting scientist at the High Altitude Observatory.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
19.
J. R. Kuhn K. S. Balasubramaniam G. Kopp M. J. Penn A. J. Dombard H. Lin 《Solar physics》1994,153(1-2):143-155
Full Stokes polarimetry is obtained using the National Solar Observatory Vacuum Tower Telescope at Sacramento Peak while observing the magnetically sensitive infrared Fei line at wavelength of 1.56. A technique is described which makes use of the high magnetic resolution in this spectral range to remove instrumental polarization from observed StokesQ, U, andV line profiles.Supported under a USAF/AFOSR research initiative.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation. 相似文献
20.
O. M. El Mekki 《Solar physics》1985,96(2):397-411
Over-reflection of propagating hydromagnetic planetary-gravity waves incident on the current sheets of the helmet streamers and magnetic sectors of the solar corona is investigated.It is shown that over-reflection arises only if the wavenumbers, or the energy fluxes per unit mass, perpendicular to the current sheet of the incident and the transmitted waves in both cases are in opposite directions. The over-reflected waves then draw magnetic energy from the sun's field and communicate it to the interplanetary magnetic field.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献