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1.
J. M. Fontenla 《Solar physics》1979,64(1):177-186
Intensities and profiles of the H, H, H, K, and D3 lines are measured in a solar prominence. From the profiles of these lines we estimate T = 6400 K and
t = 5.7 km s–1. We construct a simple isothermal model which explains the H intensity and profile for an assumed total particle density n
T = 3 × 1011 cm–3, and a filling factor, = 1/6.From this model we find that the source function in the H line is nearly constant through the prominence. We estimate from the model that the radiative energy loss at the center of the prominence is of the order of 107 erg s–1 g–1. 相似文献
2.
Slit spectrograms of a quiescent prominence and the inner corona (h2.5 arc min) in the range 3400–7000 Å (dispersion 6–10 Å/mm) were obtained. From an analysis of the Stark effect on the Balmer lines (up to number 36) the electron density in the prominence n
e = (7 ± 3) × 1010 cm–3 was deduced. The kinetic temperature T
k and the non-thermal velocities
t, found from a simultaneous consideration of the Balmer and metal lines, are T
k 10 000 K and v
t6 km/s. Also the emission measure of the prominence along the line-of-sight was found: ME = 1031 cm–5.In the coronal spectrum 24 coronal lines were found. Thirteen of these lines were identified and measured photometrically to get their absolute intensities, profiles and halfwidths. For nine lines the intensities as a function of the height were studied and on this basis the coronal lines were divided into a few groups. The line-of-sight and non-thermal velocities are
r 10 km/s and
t 25 km/s. The coronal lines originate in at least three types of regions with different temperatures. The emission measure as a function of the ionization temperature was determined. The abundances of four elements of the iron group (V, Cr, Mn, Co) were estimated. The abundances of the other elements of the same group (A, Ca, Fe, Ni), found from EUV-data, are in a good agreement with our observations. The degree of inhomogeneity in the corona was estimated:
. 相似文献
3.
Thermal and electrical conductivities due to electron scattering on phonons are calculated for degenerate cores of white dwarfs and envelopes of neutron stars for wide ranges of density, temperature and ion charge. In the stellar zones, in which T pi(Z1/3e2/F) (piis the ion plasma frequency and F the Fermi velocity of electrons), the main contribution into scattering comes from the Umklapp processes. In the zones with lowerT, the Umklapp processes are frozen out, that results in a sharp growth of electrical and thermal conductivities. This, for instance, should make nuclear burning more stable in such zones. 相似文献
4.
A spectroscopic investigation of a quiescent prominence has been performed: the line profiles of the H and K lines have been carefully determined in all regions of the prominence where these emissions are likely to originate in optically thin layers. Therefore we have been able to study the electron temperature T
e and the microturbulent velocity in the outer parts of the prominence. We find that on the average, T
e = 5700 K (Figure 1) and = 6.7 km s-1 (Figure 2) which are in very good agreement with classical data. Figure 3 represents the radial velocity measurements and Figure 4 the ratio of the total intensity of H to K lines. Thus the prominence we have observed does not show for T
e and the regular increase outward which has been described by Hirayama (1971). On the other hand increases towards the Equator, in the dynamically active part of the prominence, which could indicate that represents the effect of macroturbulence rather than microturbulence (Kawaguchi, 1966). In this part of the prominence only the K line is in emission and the average value of the microturbulence is 9.4 km s-1, the radial velocity is also generally increasing. At last, according to the absolute intensities of the H and K lines, the electron density in the outer layers of the prominence is no more than 1 × 1010 cm-3. 相似文献
5.
We derive upper limits to the radiation temperaturesT
t(k) for emission near the fundamental and second harmonic of the electron plasma frequency in terms of the effective temperature for plasma wavesT
l(k). We findT
t(k)(c/(3)1/2
V
e)3
T
l(k) for emission near the fundamental which differs from the result of Melrose (1970b) by the factor in parentheses. This factor can exceed 4×104 in some plasmas. The conditions under which this limit could be reached are delinated. For emission near the second harmonicT
t(k)T
l(k) since the absorption coefficient in this case can only be positive.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
6.
Observations of the lines He i 3888 and H8 in 80 quiescent prominences by the author, and in other prominences by Kubota et al. (1972) and Morozhenko (1971), have been used to derive the dependences of I(3888)/I(H8) on I(H8), N
2
3
s
on 0 (H), and N
+
n
e
on 0(H) (Figures 1, 2, 3 and 4). The equations of ionization equilibrium and triplet system steady state for a helium atom (27 levels and continuum were considered) were solved together with the radiation transfer equation in the helium Lyman continuum. As given n
e
() distribution with depth and T
e
=7500 K were assumed. The 23
S level population N2
3
s, helium emission measure N
+
n
e
and the intensity ratios of the He i 3888 and H8 lines were calculated and compared with observation (Figures 2, 3 and 4, solid lines). The figures show that in bright prominences the observed values of N
2
3
s and N
+
n
e
are systematically higher than the calculated ones. These deviations cannot be eliminated by decreasing n
e
. One can make the calculations and observations agree for bright prominences by increasing the UV radiation which penetrates into the prominence. 相似文献
7.
We consider the effect that coherent motion has on the observed brightness of moving clouds above the photosphere. We find that steady state clouds (constant N
e
and T
e
) that are moving perpendicular to the line of sight will appear brighter in H for speeds between 8 and 100 km/sec and dimmer for speeds greater than 135 km/sec. The brightening and dimming are due to apparent Doppler shifts of the respective H absorption and the Lyman- emission profiles seen by the absorption profile of the moving cloud.We apply this analysis, along with optical depth and geometrical considerations, to the observed brightness variations of the 1 March 1969 limb eruptive prominence. We find that all of the observed brightening and dimming can be explained by the motions, and that no significant change in the prominence N
e
or T
e
was necessary during the observed H event. This conclusion is significant in interpreting an X-ray burst that began as the prominence velocity increased abruptly at the time of maximum H intensity. The thermal X-ray peak occurred 150 sec later when the prominence had become faint again. There was no associated flare that was visible in H. We discuss the relative brightness of H and D
3 in a specific moving prominence knot.We note that the observed range of limb speeds (30–150 km/sec) may be due to the combined H Doppler brightening and Lyman- dimming effects. We also discuss generally the H brightness of disk surges (bright and dark) and flares, and sprays and puffs that occur at or near the limb.Now at the Dept. of Physics and Astrophysics, University of Colorado, and High Altitude Observatory (NCAR) Boulder, Colo., U.S.A. 相似文献
8.
Free convection in a conducting liquid past an infinite porous vertical flat plate in a rotating frame of reference when the Hall current is present is considered. Exact solutions for the velocity and temperature fields have been derived. The effects ofM (Hartmann number),m (Hall parameter), andE (Ekman number) on the velocity field are discussed.Nomenclature
C
p
specific heat at constant pressure
-
g
acceleration due to gravity
-
E
Ekman number
-
G
Grashof number
-
H
0
applied magnetic field
-
j
x
,j
y
,j
z
components of the current densityJ
-
k
thermal conductivity
-
M
Hartmann number
-
m
Hall parameter
-
P
Prandtl number
-
Q
heat flux per unit area
-
T
temperature of the fluid near the plate
-
T
w
temperature of the plate
-
T
temperature of the fluid in the free-stream
-
u, v, w
components of the velocity fieldq
-
U
uniform free-stream velocity
-
w
0
suction velocity
-
x, y, z
Cartesian coordinates
-
z
dimensionless coordinate normal to the plate
Greek symbols
coefficient of volume expansion
-
e
cyclotron frequency
-
e
electron collision time
-
u
skin friction in the direction ofu
-
v
skin friction in the direction ofv
-
dimensionless temperature
-
density of the fluid
-
kinematic viscosity
-
e
magnetic permeability
-
electrical conductivity of the fluid
-
angular velocity 相似文献
9.
The mass ejection event on 17 January 1974 was a classsic spray associated with a flare from an over the limb region. The structure of the accompanying coronal transient was typical of well-observed mass ejections, with coronal loops and a forerunner racing ahead of the rising prominence. Observations in H, soft X-ray, white light and radio wavelengths allowed us to track both cool (T
e104 K) and hot (T
e>106 K) material from limb de-occultation to 6R
. We determined the kinematics and thermodynamics of the internal material, and the overall mass and energy budget of the event. The majority of the mass and energy was linked with coronal material, but at least 20% of the ejected mass originated as near-surface prominence material. We conclude that the upper part of the prominence was being continuously heated to coronal temperatures as it rose through the corona. Above 2R
nearly all of the material was completely ionized. The primary acceleration of the prominence occurred below 3.5 × 104 km with all of the material exhibiting constant velocity above 1.5R
. We found evidence that a moving type IV burst, indicative of strong magnetic fields, was associated with the upper part of the prominence. Our observations suggest that both the cool and hot material were acted upon by a similar, continuous force(s) to great heights and over a long time interval. We find that the observations are most consistent with magnetic propulsion models of coronal transients. 相似文献
10.
The statistical equilibrium equations for the continuum and first 10 levels of a hydrogen atom show that the radiation of a bright prominence (the brightness of the H line has attained 56 mÅ of the disc centre spectrum) is completely due to scattering of the Sun radiation. The basic unknowns are separated with certainty: electron concentration (n
e = 3.0 × 1010 cm–3), effective thickness (l = 4.2 × 108 cm) and electron temperature (T
e = 5000 K).Radiation of a very bright prominence (A
(H) = 213 mÅ; T
e = 7300 K; n
e = 5.0 × 1011 cm–3; l = 1.3 × 107 cm) is on account of electron impacts (40%) and the Sun radiation scattering (60%).The parameters are shown to depend greatly on the prominence optical thickness in the lines of the first subordinate series of a hydrogen atom. In the course of determination all the parameters and 100 interconnected integral equations of the radiation diffusion have been thickness-averaged; the population of levels has been calculated by observations using the self-absorption factors. 相似文献
11.
Basil Zafiropoulos 《Astrophysics and Space Science》1987,139(1):111-128
The equations for the variation of the osculating elements of a satellite moving in an axi-symmetric gravitational field are integrated to yield the complete first-order perturbations for the elements of the orbit. The expressions obtained include the effects produced by the second to eighth spherical harmonics. The orbital elements are presented in the most general form of summations by means of Hansen coefficients. Due to their general forms it is a simple matter to estimate the perturbations of any higher harmonic by simply increasing the index of summation. Finally, this paper gives the respective general expressions for the secular perturbations of the orbital elements. The formulae presented should be useful for the reductions of Earth-satellite observations and geopotential studies based on them.List of Symbols
semi-major axis
- C
jk
n
(, )
cosine functions of and
-
e
eccentricity of the orbit
-
f
acceleration vector of perturbing force
-
f
sin2t
- i
inclination of the orbit
-
J
n
coefficients in the potential expansion
-
M
mean anomaly
-
n
mean motion
-
p
semi-latus rectum of the orbit
-
R, S, andW
components of the perturbing acceleration
-
r
radius-vector of satellite
-
r
magnitude ofr
-
S
jk
n
(, )
sine functions of and
-
T
time of perigee passage
-
u
argument of latitude
-
U
gravitational potential
-
true anomaly
-
V
perturbing potential
-
G(M++m) (gravitational constant times the sum of the masses of Earth and satellite)
- n,k
coefficients ofR component of disturbing acceleration (funtions off)
- n,k
coefficients ofS andW components of disturbing acceleration (functions off)
-
mean anomaly at timet=0
-
X
0
n,m
zero-order Hansen coefficients
-
argument of perigee
-
right ascension of the ascending node 相似文献
12.
A large surge event appearing in AR 5395 was observed at the Yunnan Observatory on March 19, 1989. H spectral profiles of the event are interpreted by using a two-cloud model and the contours of three parameters: excitation temperature, T
exc, microturbulent velocity, V
t
,and column density of hydrogen atoms at the second level, N
0,2, are obtained, respectively. The question about the unique feature of the solution obtained by the fitting method is also discussed. The results show that the surge is composed of some conglomerated materials with higher temperature and density; the mass ejection is probably intermittent. Neither T
exc nor N
0,2 vary with the height over the solar limb but decrease from the center to the periphery of the surge. V
t
varies from 10 to 30 km s-1 and decreases with height. Some other important parameters, such as electron density, n
e
,and electron pressure, P
e
,etc., have also been estimated. In the surge, with N
0,2 about 2.0 × 1012 cm-2 and T
exc about 8500 K on average, we obtained n
e
= 1.80 × 1010 cm-3 and P
e
= 0.023 dyn cm-2. The energy variations of the surge during the ascending phase are estimated. 相似文献
13.
Four different models for a K-giant atmosphere (T
e=4500K, logg=2) have been computed. Each model is characterized by the inclusion of different opacity sources (H, H–, (H), metals, blanketing effect, He–) in order to obtain an evaluation of the model sensitivity concerning the atmospheric structure and the emergent flux. The results show that hydrogen, metals and blanketing effect must be taken into account to achieve self-consistent and reliable models.A picture of the influence of the frequency distribution of the absorption coefficient on the model features is also shown.
Sommario Sono stati calcolati quattro differenti modelli di una stella gigante K(T e=4500K, logg=2). Ogni modello è caratterizzato dalla inclusione di differenti sorgenti di opacità (H, H–, (H), metalli, effetto blanketing, He–) per ottenere una valutazione della sensibilità del modello per quel che riguarda la struttura atmosferica ed il flusso emergente. I risultati ottenuti mostrano che per costruire modelli auto-consistenti e con un buon grado di affidabilità occorre tener conto almeno delle seguenti sorgenti di opacità: H, metalli, effetto blanketing.Si mostra inoltre come sia possibile una descrizione schematica dell'influenza del coefficiente di assorbimento sulle varie caratteristiche del modello.相似文献
14.
The physical properties in the coronal disturbance (CD) (W90, N25°) associated with an active prominence are investigated on the basis of the intensities and profiles of 5694 Å Caxv and 6702 Å Nixv lines and continuum measured in the eclipse coronal spectra of 31 July, 1981. The spectrograms have been taken with a dispersion of between 7 to 10 Å mm-1 and a solar image of 15 mm in diameter. The following characteristics of the CD have been deduced. The CD occurred cospatially with an active prominence and consisted of two discrete regions with different temperatures penetrating each other. (1) Caxv region: T
e= 3.8 × 106 K, the length along the slit of the spectrograph Z 65000 km, the effective line-of-sight length L 20000 km, the average electron density
, nonthermal velocities V
t= (20–32) km s-1. (2)Nixv-Caxiii region: T
e= 2.3 × 106 K, Z 37000 km, L 35000 km, n
e 1 × 109 cm-3, V
t= (23–30) km s-1. A macroscopic mass motion has been discovered within the Nixv region of the CD from the Doppler shifts of the 6702 Å Nixv line: V
r= + 27 km s-1 on the lower and V
r= - 12 km s-1 on the upper border of the CD. The average height of the CD was H 0.08 R
. The radial velocities in the prominence found from the emission line tilts are + 12 and - 8 km s-1 on its lower and upper borders. A similar picture of the mass motion in the CD and the prominence speaks in favour of an intimate relation between them. 相似文献
15.
R. B. Shatsova 《Astrophysics and Space Science》1993,201(1):91-105
Many HVC - high velocityHi clouds - are added to the known combination of diffuse soft X-rays and radioloops. Among these HVC there are previously examined complexes A, C, Magellanic Stream, etc. Their common composition has a clear geometry and kinematics.Two powerful long HVC filaments form the bridges between Loop I and double Loop II + III. The Bridges join the polarX
max regions in C band. The bridges ends at Loop I side are bounded by the systems of shorter filaments withX
max spots in M1 and larger energy bands. There are no HVC in the spots themselves. The opposite ends of bridges reach Loops II and III centres. The two structures have the features of rotational symmetry.The isolines X-ray count rates pass along HVC chains with the same
r
-velocities. The frequent alternation of different
r
on the same filament is better explained by the turbulent gas motion than by the differences of HVC distance.All of the above-mentioned, as well as the
r
signs of dependence on the galactical longitude, are the result of HVC interaction with X-rays. The whole composition from HVC-loops-X-rays is a component of the local system (Gould Belt). 相似文献
16.
This study considers the influence of the effects of scattering due to Langmuir turbulent pulsations in the transfer of radiation in the spectral lines. The transfer equation of radiation in spectral lines, by taking into account scattering due to Langmuir turbulent pulsations, is written in a form convenient for application by numerical methods.The profile's intensity for a plane-parallel finite isothermal slab of a turbulent plasma in the case of complete redistribution of scattering by an atom are obtained. Numerical studies show that in this case with the broadening of spectral lines and the decreasing of self-reversal, the Langmuir frequency
pe is of the same order as the electronic Doppler width
De. Creation of the line satellites when
pe is larger than the line width is shown with the aid of numerical methods. 相似文献
17.
G. Dautcourt 《Astrophysics and Space Science》1976,43(2):L1-L2
Low-frequency gravitational radiation, with wavelengths reaching or exceeding interplanetary distances, and with a mean energy density of the order of the critical cosmological density
c
, generates a frequency-shift of order/10–15
h
0(1/108km)(/
c
)1/2 in electromagnetic signals transponded by interplanetary spacecraft at a distancel from the Earth. 相似文献
18.
We report multifrequency observations of storm continuum and other radio bursts. Based on their positional study and their correlation with other coronal and photospheric features, we deduce that the storm source is located in the magnetic field lines lying above a single bipolar active region. Energetic electrons trapped in the magnetic structures above the spots must be responsible for the storm radiation. We show that spontaneous emission of Langmuir waves by anisotropic distributions can explain both storm continuum and bursts self-consistently. Whenever the collisional damping (
c
) is more than the growth (-
A
), there is a steady emission responsible for the continuum, and whenever
c
= -
A
(which may be satisfied randomly) there is a sudden jump in T
b
giving rise to bursts. The number density of energetic particles required to explain the storm continuum at 73.8, 50, and 30.9 MHz frequencies is estimated to lie in the limits n
b
/n
e
10–10–10–9 in the context of the present observations. The brightness spectrum of the storm continuum is computed and compared with observations.On leave from Indian Institute of Astrophysics, Bangalore 560034, India. 相似文献
19.
Drake Deming John J. Hillman Theodor Kostiuk Michael J. Mumma David M. Zipoy 《Solar physics》1984,94(1):57-74
We have obtained low noise (S/N > 103), high spectral resolution (/ 10
6) observations of two pure rotation transitions of OH from the solar photosphere. The observations were obtained using the technique of optically null-balanced infrared heterodyne spectroscopy, and consist of center-to-limb line profiles of a = 1 and a = 0 transition near 12 m. These lines should be formed in local thermodynamic equilibrium (LTE), and are diagnostics of the thermal structure of the upper photosphere. We find that the = 0R22(24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one-dimensional photospheric models. Our data for this line support a two-dimensional model in which horizontal thermal fluctuations of order ±800 K occur in the region 5000 10–3–10–2. This thermal bifurcation may be maintained by the presence of magnetic flux tubes, and may be related to the solar limb extensions observed in the 30–200 m region.Observations of the = 1R11(29.5)f line, at 885.643 cm–1, show that it is anomalously weak in the photospheric spectrum. We argue that the source function in the core of this line has been substantially increased by interaction with the 9j-7i transition of Mgi at 885.524 cm–1, which is itself too weak to appear in the disk center spectrum.Visiting Astronomer, Kitt Peak National Observatory, which is operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation. 相似文献
20.
The present work is a review of papers related to the theory of prominence radiation. Special attention is paid to stationary equations and the theory of radiation diffusion in the lines and continua of hydrogen, helium and metals.We conclude that prominences are low-temperature formations T
e
7000 K, of low density 1012 particles per cm3, n
e
1011 cm–3, effective thickness 109 cm, and that the chemical composition of prominences and that of the Sun's atmosphere are the same. The prominence radiation in the lines of hydrogen, helium and metals is due mainly to quasiresonance scattering of the photospheric radiation. 相似文献