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1.
2.
Corrections are given which transform the Tables of the solar radiation data (Labs and Neckel, 1968) into the International Practical Temperature Scale of 1968. Additionally, for the adjustment of the data of the true continuum and the corresponding line blanketing as well, the veiled line effect mentioned first by Carbon et al. (1968), but studied in more detail by Holweger (1970a), has been considered also.The corresponding corrections of the solar irradiance result in an improved value of the spectrophotometric solar constant: S = 1.947 cal cm-2 min-1 or 0.1358 W cm-2. Two Tables presenting the highest (window-) intensities and the corrected irradiance data have been added. 相似文献
3.
Analyses based on irradiance observations from space within the last one and a half decades have discovered variations in the entire solar spectrum and at UV wavelengths on time scales of minutes to decades. In this paper we analyze the distribution of the measuring uncertainties and daily fluctuations in total solar irradiance measured by the Nimbus-7/ERB and SMM/ACRIM I radiometers as a function of solar cycle. Changes in solar total irradiance and its surrogates shorter than the solar rotation have also been considered as noise and have been removed from the data. Our results show that the noise (both instrumental and solar noise) changes as a function of the solar cycle, being higher during high solar activity conditions. The analysis of the scatter plot diagrams between the data and their standard deviation, the so-called dispersion diagrams, provides a useful tool to estimate and predict the time of solar maximum and minimum activity conditions.Deceased on October 13, 1994. 相似文献
4.
The observed distribution of waiting times t between X-ray solar flares of greater than C1 class listed in the Geostationary Operational Environmental Satellite (GOES) catalog exhibits a power-law tail (t) for large waiting times (t>10hours). It is shown that the power-law index varies with the solar cycle. For the minimum phase of the cycle the index is =–1.4±0.1, and for the maximum phase of the cycle the index is –3.2±0.2. For all years 1975–2001, the index is –2.2±0.1. We present a simple theory to account for the observed waiting-time distributions in terms of a Poisson process with a time-varying rate (t). A common approximation of slow variation of the rate with respect to a waiting time is examined, and found to be valid for the GOES catalog events. Subject to this approximation the observed waiting-time distribution is determined by f(), the time distribution of the rate . If f() has a power-law form for low rates, the waiting time-distribution is predicted to have a power-law tail (t)–(3+) (>–3). Distributions f() are constructed from the GOES data. For the entire catalog a power-law index =–0.9±0.1 is found in the time distribution of rates for low rates (<0.1hours
–1). For the maximum and minimum phases power-law indices =–0.1±0.5 and =–1.7±0.2, respectively, are observed. Hence, the Poisson theory together with the observed time distributions of the rate predict power-law tails in the waiting-time distributions with indices –2.2±0.1 (1975–2001), –2.9±0.5 (maximum phase) and –1.3±0.2 (minimum phase), consistent with the observations. These results suggest that the flaring rate varies in an intrinsically different way at solar maximum by comparison with solar minimum. The implications of these results for a recent model for flare statistics (Craig, 2001) and more generally for our understanding of the flare process are discussed. 相似文献
5.
We have compared three years of daily CaII K-line images from the Big Bear Solar Observatory (BBSO) with HI Lyman irradiance data from the Upper Atmosphere Research Satellite (UARS). The daily full-disk CaII K-line images are reduced to a new index of integrated excess emission, which reproduces both the 27 day rotational modulation and the solar cycle decrease in Ly irradiance. Our analysis shows that while plages reproduce the 27-day variation quite well, the total K-line emission excess above the quiet background is needed to reproduce the secular solar cycle trend in the Ly irradiance. The resulting K-line index exhibits a high degree of correlation (0.9) with the time series of measured Ly flux. 相似文献
6.
A crossed Yagi antenna array at 35 MHz was employed in conjunction with a polarization switch so as to enable spectral observations of solar noise storm activity in R and L polarizations. Intense decametric solar noise storms were recorded during the third week of November 1975 and fourth week of March 1976 with the help of a high resolution spectroscope operating near 35 MHz.The paper describes some of the new microscopic spectral features observed during these two noise storms. Three sets of high resolution dynamic spectra of decametric solar bursts, two of which are explained in terms of induced scattering of Langmuir waves by thermal ions and the third in terms of additional propagation effects through dense coronal irregularities, are presented. The microscopic bursts, classified as inverted U U and dots, represent small-scale (104 km) phenomena with durations of less than a second.Some burst spectra appear as chain of dots with individual bandwidths 40 kHz and durations 0.3 sec. It is suggested that the bandwidth of such dot emissions (40 kHz) provides an evidence that they might indeed be generated by the process of induced scattering of plasma waves which predicts emission bandwidth f × 10–3, where f is the center frequency.Some bursts are observed as a chain of striations showing curvature along the frequency axis which is attributed to dispersion in propagation delays through the dense coronal irregularities. 相似文献
7.
The analysis of solar wind He++ and H+ ion distribution functions, collected over five months by the satellite Prognoz 1, shows that these are in general maxwellian but that often tails appear at higher speeds. The existing relation V-T, the observation of ratios of T/Tp 3.83 and V/Vp 1.035 give evidence of preferential He++ ion heating and acceleration. The criteria for heating by dissipation of hydromagnetic waves proposed by Barnes and Hung (1973) are tested experimentally. Finally, multifluid models are likely to predict certain observations such as dependence of the velocity ratio V/Vp on the solar wind flux. 相似文献
8.
Using the results of numerical simulations of the solar atmospheric response to heating by nonthermal electron beams during solar flares, we have calculated the spatial and temporal evolution of both (i) the direct (beam-target) nonthermal bremsstrahlung and (ii) the thermal bremsstrahlung arising from the hot plasma energized by the electron beam. Typically, we find that below a certain cross-over energy E
*, the emission is dominated by the thermal component, while at higher energies the direct bremsstrahlung component becomes more important. This cross-over energy is dependent on the position within the loop, generally increasing with height.We have also investigated the dependence of the cross-over energy E
* on the parameters of the electron energy input. At the time of peak electron flux injection the cross-over energy E
* can, for plausible parameters, be as high as 52 keV at the top 1 pixel, and as low as 16 keV at the bottom 1 pixel. We conclude that a possible reassessment of SMM HXIS data as an indicator of the thermal or nonthermal character of the primary energy release (based primarily on the geometric properties of the hard X-ray source) is required. Our results also point to the minimum photon energy that future instruments should observe (where practical, giving due consideration to detector sensitivity) in order to be sure that, in the context of the thick-target interpretation, the nonthermal component is not swamped by the self-consistent thermal counterpart created by the beam heating. 相似文献
9.
Using the flux-transport equation in the absence of sources, we study the relation between a highly peaked polar magnetic field and the poleward meridional flow that concentrates it. If the maximum flow speed
m greatly exceeds the effective diffusion speed /R, then the field has a quasi-equilibrium configuration in which the poleward convection of flux via meridional flow approximately balances the equatorward spreading via supergranular diffusion. In this case, the flow speed () and the magnetic field B() are related by the steady-state approximation () (/R)B()/B() over a wide range of colatitudes from the poles to midlatitudes. In particular, a general flow profile of the form sin
p
cos
q
which peaks near the equator (q p) will correspond to a cos
n
magnetic field at high latitudes only if p = 1 and
m = n /R. Recent measurements of n 8 and 600 km2 s–1 would then give
m 7 m s–1. 相似文献
10.
Polarization properties of solar and stellar radio emission require, in some cases, emission below the third or fourth coronal electron gyro level, < 3,_c; 4, _c. In the context of plasma radiation, the source parameters should be such that the intermediate magnetic field condition 1 <
p
2
/
c
2
< 3 is satisfied. Supposing this condition, we investigate the generation of electrostatic waves in a warm background plasma with a high-energy component of magnetically trapped electrons. We invoke the conversion of upper-hybrid waves and Bernstein waves into electromagnetic radiation as being responsible for intense radio emission from a coronal magnetic loop. Moreover, odd-half harmonic emissions in the solar radio spectrum as well as the o-mode polarization at the second harmonic of the plasma frequency are natural consequence of this proposed model. 相似文献
11.
The recent discovery of localised intense magnetic fields in the solar photosphere is one of the major surprises of the past few years. Here we consider the theoretical nature of small amplitude motions in such an intense magnetic flux tube, within which the field strength may reach 2 kG. We give a systematic derivation of the governing expansion equations for a vertical, slender tube, taking into account the dependence upon height of the buoyancy, compressibility and magnetic forces. Several special cases (e.g., the isothermal atmosphere) are considered as well as a more realistic, non-isothermal, solar atmosphere. The expansion procedure is shown to give good results in the special case of a uniform basic-state (in which gravity is negligible) and for which a more exact treatment is possible.The form of both pressure and velocity perturbations within the tube is discussed. The nature of pressure perturbations depends upon a critical transition frequency,
p
, which in turn is dependent upon depth, field strength, pressure and density in the basic (unperturbed) state of the tube. At a given depth in the tube pressure oscillations are possible only for frequencies greater than
p
for frequencies below
p
exponentially decaying (evanescent) pressure modes occur. In a similar fashion the nature of motions within the flux tube depends upon a transition frequency,
v
. At a given depth within the tube vertically propagating waves are possible only for frequencies greater than
v
; for frequencies below
v
exponentially decaying (evanscent) motions occur.The dependence of both
v
and
p
on depth is determined for each of the special cases, and for a realistic solar atmosphere. It is found that the use of an isothermal atmosphere, instead of a more realistic temperature profile, may well give misleading results.For the solar atmosphere it is found that
v
is zero at about 12 km above optical depth 5000= 1, thereafter rising to a maximum of 0.04 s–1 at some 600 km above 5000 = 1. Below 5000 = 1, in the convection zone,
v
has a maximum of 0.013 s–1. The transition frequency,
p
, for the pressure perturbations, is peaked at 0.1 s–1 just below 5000 = 1, falling to a minimum of 0.02 s–1 at about one scale-height deeper in the tube 相似文献
12.
Multiple expansion of the tidal potential 总被引：1，自引：0，他引：1
F. Mignard 《Celestial Mechanics and Dynamical Astronomy》1978,18(3):287-294
The Earth tidal deformation causes an additional gravitational potential. Its effect on the Moon orbital motion has been studied by several authors.In this contribution, we develop this additional potential without specifying the inertial frame chosen.For this purpose, we use the properties of the representation of rotation groups in 3 dimensions space. We finally obtain the interaction potential between the distorted Earth and the Moon which is a necessary preliminary to the study of the evolution of the Earth-Moon system.Nomenclature T.R.O
Tide raising object
- (, , )
Spherical coordinates of the T.R.O.
- (J,
E
)
Earth spin axis orientation.
E
is the longitude of the ascending node of Earth's equator on thexy-plane
- (a
,I
,e
, , ,M
)
Elliptics elements of the T.R.O 相似文献
13.
Boris Garfinkel 《Celestial Mechanics and Dynamical Astronomy》1980,22(3):267-287
In the previously published Parts I and II of the paper, the author has constructed a formal long-periodic solution for the case of 11 resonance in the restricted problem of three bodies to 0(m
3/2), wherem is the small mass parameter of the system. The time-dependencet(, ,m), where is the mean synodic longitude and is related to the Jacobi constant, has been expressed by ahyperelliptic integral. It is shown here that with the approximationm=0 in the integrand, the functiont(, , 0) can be expanded in a series involving standardelliptic functions. Then the problem of inversion can be formally solved, yielding the function (t, , 0).Similarly, the normalized period (,m) of the motion can be approximated by theHagihara hyperelliptic integral (, 0), corresponding tom=0. This integral is also expanded into elliptic functions. Asymptotic forms for (, 0) are derived for 0 and for 1, corresponding to the extreme members of thetadpole branch of the family of orbits. 相似文献
14.
R. Grant Athay 《Solar physics》1988,116(2):223-237
An attempt is made in this paper to determine the coefficient a in a power-law relationship of the form V
~T
between the r.m.s. velocity fluctuation, V
for raster images with 3 resolution and the temperature, T of line formation using SMM solar data. For T between 8000 and 105 K, the data suggest a best fit with 3/4 < 1. It is argued, however, that unresolved fine structure tends to reduce the observed value of V
and that higher resolution data may yield different values for . Skylab data have shown that the non-thermal line broadening velocity, , is proportional to T
1/2. Also, for all temperatures less than 105 K, V
. This latter result, however, is again dependent on spatial resolution and may not be true in observations made with sufficient spatial resolution. The magnitudes of both V
and indicate that bulk motions play important roles in the structure of the solar atmosphere as well as in its energy and momentum balance. It is important, therefore, to identify the true nature of such motions with better accuracy than is possible with currently available data.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
15.
M. R. Kundu 《Solar physics》1972,25(1):108-115
At 3.5 mm wavelength absorption features are observed in correspondence with H dark filaments on the disk; beyond the limb the prominences correspond to emissive regions. The absorption features are larger (2–3 arc) than the corresponding H dark filaments; the emissive regions at the limb have similar angular sizes. The emissive regions at the limb have electron temperatures of 5500±500 K; the amount of absorption observed on the disk leads to mean electron densities of about 5 × 1010 per cm3. 相似文献
16.
An analysis of the effects of Hall current on hydromagnetic free-convective flow through a porous medium bounded by a vertical plate is theoretically investigated when a strong magnetic field is imposed in a direction which is perpendicular to the free stream and makes an angle to the vertical direction. The influence of Hall currents on the flow is studied for various values of .Nomenclature
c
p
specific heat at constant pressure
-
e
electrical charge
-
E
Eckert number
-
E
electrical field intensity
-
g
acceleration due to gravity
-
G
Grashof number
-
H
0
applied magnetic field
-
H
magnetic field intensity
- (j
x
, j
y
, j
z
)
components of current densityJ
-
J
current density
-
K
permeability of porous medium
-
M
magnetic parameter
-
m
Hall parameter
-
n
e
electron number density
-
P
Prandtl number
-
q
velocity vector
- (T, T
w
, T
)
temperature
-
t
time
- (u, v, w)
components of the velocity vectorq
-
U
0
uniform velocity
-
v
0
suction velocity
- (x, y, z)
Cartesian coordinates
Greek Symbols
angle
-
coefficient of volume expansion
- e
cyclotron frequency
-
frequency
-
dimensionless temperature
-
thermal conductivity
-
coefficient of viscosity
-
magnetic permeability
-
kinematic viscosity
-
mass density of fluid
- e
charge density
-
electrical conductivity
- e
electron collision time 相似文献
17.
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
18.
Matthew J. Penn Donald L. Mickey Richard C. Canfield Barry J. Labonte 《Solar physics》1991,135(1):163-177
The Mees CCD (MCCD) instrument is an imaging spectroscopy device which uses the 25 cm coronagraph telescope and the 3.0 m Coudé spectrograph at Mees Solar Observatory (MSO) on Haleakala, Maui. The instrument works with resolving power up to R 200 000 with significant throughput from 3934 Å (Caii K) to 10 000 Å. A fast guiding active mirror stabilizes the image during observations. A rapidly writing magnetic tape storage system allows observations to be recorded at 256 kbytes s–1. Currently, the MCCD is used for imaging spectroscopy of solar flares at 6563 Å (H), and velocity measurements of umbral oscillations; future plans include emission line studies of active region coronae, and photospheric studies of solar oscillations. 相似文献
19.
Steven Phillipps 《Astrophysics and Space Science》1996,240(2):241-247
The geometry of space at high redshifts is dependent on the value of the cosmological constant (or its normalised contribution to the curvature of space, 0). Here we investigate the prospects for constraining 0 from the apparent dimensions of structures seen at very highz. As an example we consider the single highest redshift structure currently known, atz=3.4. We show that there can be substantial differences in apparent orientation, depending on the cosmological model assumed, in particular the radial stretching at highz can lead to structures inprobably well aligned with the line of sight if we (incorrectly) assume a large value of 0. In our example we are limited by the effect of the (unknown) dynamics within this cluster/supercluster. However, a suitably well defined, relatively small, sample of large structures at highz, along with a study of their velocity fields, may provide an alternative, and complementary, approach to the use of very large statistical samples as required by previously suggested methods. 相似文献
20.
P. E. Zadunaisky 《Celestial Mechanics and Dynamical Astronomy》1979,20(3):209-230
There exist several widely used methods that give a qualitative estimation of the accuracy of the results in the numerical solution of theN-body problem. The reverse and closure tests are examined here critically. The author has developed a method for the estimation of global errors propagated in the numerical solution of ordinary and partial differential equations that has proven to be rather efficient in numerous cases (see P. E. Zadunaisky [17]). Applications of the method to several cases of theN-body problem are presently made and the advantages and limitations of the method are shown in a set of examples. 相似文献