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1.
It is shown on the basis of analyzing the LASCO/SOHO data that the main quasi-stationary solar wind (SW), with a typical lifetime of up to 10 days, flows in the rays of the streamer belt. Depending on R, its velocity increases gradually from V3 km s–1 at R1.3 R
to V170 km s–1 at R15 R
. We have detected and investigated the movement of the leading edge of the main solar wind at the stage when it occupied the ray, i.e., at the formative stage of a quasi-stationary plasma flow in the ray. It is shown that the width of the leading edge of the main SW increases almost linearly with its distance from the Sun. It is further shown that the initial velocity of the inhomogeneities (`blobs') that travel in the streamer belt rays increases with the distance from the Sun at which they originate, and is approximately equal to the velocity of the main solar wind which carries them away. The characteristic width of the leading edge of the `blob' R
, and remains almost unchanging as it moves away from the Sun. Estimates indicate that the main SW in the brightest rays of the streamer belt to within distances at least of order R3 R
represents a flow of collisional magnetized plasma along a radial magnetic field. 相似文献
2.
The electrical conductivity of the lunar interior has been determined from magnetic field step transients measured on the lunar dark side. The simplest model which best fits the data is a spherically symmetric three layer model having a nonconducting outer crust of radial thickness 0.03R
moon; an intermediate layer of thicknessR0.37R
moon, with electrical conductivity
1 3.5 × 10–4 mhos/m; and an inner core of radiusR
2 0.6R
m
with conductivity
2 10–2 mhos/m. Temperatures calculated from these conductivities in the three regions for an example of an olivine Moon are as follows: crust, < 440 K; intermediate layer, 890 K; and core, 1240 K. The whole-moon relative permeability has been calculated from the measurements to be/
0 = 1.03 ± 0.13. Remanent magnetic fields at the landing sites are 38 ± 3 at Apollo 12, 43 ± 6 and 103 ± 5 at two Apollo 14 sites separated by 1.1 km, and 6 ± 4 at the Apollo 15 site. Measurements show that the 38 remanent field at the Apollo 12 site is compressed to 54 by a solar wind pressure increase of 7 × 10–8 dynes/cm2.National Research Council Postdoctoral Associate. 相似文献
3.
A. D. Sedrakian 《Astrophysics and Space Science》1996,236(2):267-276
The phonon excitation spectrum of Coulomb lattice in the neutron star crusts is studied by solving Dyson's equation for phonons. It is shown that a strong renormalization of the phonon spectrum occurs at densities
s
/4 for the crustal matter compositions with spherical nuclei, which imply relatively small nuclear mass numbers and charges. It is shown that, the lattice becomes unstable against density fluctuations above a critical density of the order of
s
/3, where
s
2.6x1014 g cm–3 is the nuclear saturation density. The neutron quasiparticle spectrum and the virtual mass of a nucleus are briefly discussed. 相似文献
4.
Hong-Nan Zhou 《Astrophysics and Space Science》1988,141(2):199-206
The contact binary system CC Com (=12h09m33s.8, =+22°4339, (1950);V
max=11.31, (B-V)max=1.24) is a W UMa-type system with the shortest known period. The photometric solution of CC Com is presented using the Wilson and Devinney method. The results show that the CC Com belongs to the late-type eclipsing binary with the spectral type K5V and K6V, low temperatureT
1=4300 K,T
2=4265 K, the mass ratioq=0.5873±0.0021, and the inclinationi=87°.719±1°.44. The best regions of the gravity darkening exponents , the bolomotric albedov, and the limb-darkening coefficients are tested. It is found that 0.1250.065, 0.1v0.5, =0.5 are better regions for CC Com. The third body ofl
3 is not found to be significant. The results are combined with the spectroscopic results of Rucinski to provide an estimate of the absolute parameters. 相似文献
5.
Hong Wei Li 《Solar physics》1986,104(1):131-136
The variations of the growth rates of ECM at first four harmonics in X-, Z-, and O-modes excited by a hollow beam distribution of weakly relativistic electrons with a parameter
p
/
e
are presented in this paper. The results show that the second harmonic of ECM in X-mode dominates the instability if < 1, and if 1.2 , 2 or 2.2 3 the third or fourth harmonic will dominate. The second and third harmonics of Z-mode waves grow faster only if 2 2.2 and 3 3.2, respectively, so it would not be a competition in most cases. It is suggested that the ECM emission at these harmonics in X-mode is a possible mechanism to produce solar spike emissions with high brightness temperature at shorter and longer decimetric wavelengths.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.On leave from the Department of Astronomy, Nanjing University, Nanjing, The People's Republic of China. 相似文献
6.
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
7.
General theory of electrical conductivity of a multicomponent mixture of degenerate fermions in a magnetic fieldB, developed in the preceding article (this volume), is applied to a matter in neutron star interiors at densities 0, where 0 = 2.8×1014 g cm–3 is the standard nuclear matter density. A model of free-particle mixture ofn, p, e is used, with account for appearance of –-hyperons at >
c
, where
c
40. The electric resistivities along and acrossB, and , and the Hall resistivity
H
are calculated and fitted by simple analytical formulae at
c
and >
c
for the cases of normal or superfluid neutrons provided other particles are normal. Charge transport alongB is produced by electrons, due to their Coulombic collisions with other charged particles; is independent ofB and almost independent of the neutron superfluidity. Charge transport acrossB at largeB may be essentially determined by other charged particles. If
c
, one has = [1 + (B/B
0)2] for the normal neutrons, and for the superfluid neutrons, while
H
=
B/B
e
for both cases. HereB
e
109
T
8
2
G,B
01011
T
8
2
G, andT
8 is temperature in units of 108 K. Accordingly for the normal neutrons atBB
0, the transverse resistivity suffers an enhancement, 1/4 1. When 50 andB varies from 0 toBB
p
1013
T
8
2
G, increases by a factor of about 103–104 and
H
changes sign. WhenBB
p
, remains constant for the superfluid neutrons, and
H
B
2 for the normal neutrons, while
H
B for any neutron state. Strong dependence of resistivity onB, T, and may affect evolution of magnetic fields in neutron star cores. In particular, the enhancement of at highB may noticeably speed up the Ohmic decay of those electric currents which are perpendicular toB. 相似文献
8.
Lockwood, Stamper, and Wild (1999) argued that the average strength of the magnetic field of the Sun has doubled in the last 100 years. They used an analysis of the geomagnetic index aa. We calculated the area of polar zones of the Sun, A
pz, occupied by unipolar magnetic field on H synoptic magnetic charts, following Makarov (1994), from 1878 to 2000. We found a gradual decrease of the annual minimum latitude of the high-latitude zone boundaries, 2m, of the global magnetic field of the Sun at the minimum of activity from 53° in 1878 down to 38° in 1996, yielding an average decrease of 1.2° per cycle. Consequently the area of polar zones A
pz of the Sun, occupied by unipolar magnetic field at the minimum activity, has risen by a factor of 2 during 1878–1996. This means that the behavior of the index aa and consequently the magnetic flux from the Sun may be explained by an increase of the area of polar caps with roughly the same value of the magnetic field in this period. The area of the unipolar magnetic field at the poles (A
pz) may be used as a new index of magnetic activity of the Sun. We compared A
pz with the aa, the Wolf number W and A* -index (Makarov and Tlatov, 2000). Correlations based on `11-year' averages are discussed. A temperature difference of about 1° between the Maunder Minimum and the present time was deduced. We have found that the highest latitude of the polar zone boundaries of the large-scale magnetic field during very low solar activity reaches about 60°, cf., the Maunder Minimum. It is supposed that the 2m-latitude coincides with the latitude where r=0, with (r,) being the angular frequency of the solar rotation. The causes of the waxing and waning of the Sun's activity in conditions like Maunder Minimum are discussed. 相似文献
9.
Satoshi Hinata 《Astrophysics and Space Science》1978,55(2):427-439
We determine the momentum distribution of the relativistic particles near the Crab pulsar from the observed X- and -ray spectra (103109 eV), provided that the curvature radiation is responsible for it. The power law spectrum for the relativistic electrons,f()
–5, reproduces a close fit to the observed high-energy photon spectrum. The theoretically determined upper limit to the momentum (due to radiation damping),
M
8×106, corresponds to the upper cut-off energy of the -ray spectrum, 109 eV. The lower limit to the momentum,
m
1.8×105, is chosen such that flattening of the X-ray spectrum below 10 keV is simulated. The number density of these electrons is found to be much higher than the Goldreich-Julian density. We also discuss pulse shape and polarization of high-energy photons. The extremely high density of particles and the steep momentum spectrum are difficult to understand. This may imply that another, more efficient, mechanism is in operation. 相似文献
10.
In the theory of supergravity (N=1), the supersymmetric version of general relativity, and for the Kasner cosmological model (Bianchi type I) we find a non-trivial solution (for the metric and spinor-vector) under the most simple assumption =11 + 22; 12+21=0 and for a special choosed gaugeN=1,N
j=0, 0=0. This method could be also applied to other cosmological metrics and extended to enlarged Grassmann basis.O. Obregón was partially supported by the Alexander von Humboldt Stiftung. 相似文献
11.
A detailed investigation of the evolution of low-mass binaries is performed for the case when the secondary fills its Roche lobe at the stage of core hydrogen exhaustion. The obtained results are compared with observational data for ultra-short periodic X-ray systems MXB 1820-30 and MXB 1916-05. In the frame of the proposed evolutionary scenario it is possible to obtain for MXB 1820-30 its periodP=11.4 min twice (see Figure 2). In the first case the parameters of the system are:M
2 0.13–0.15M
,X0.05–0.13, |P/P| (3.6–6.2) } 10–7 yr–1, M2 (4.1–9.6) } 10–9
M
yr–1, for the second:M
2 0.08–0.09M
,X= 0, |P/P| (1.3–1.5) } 10–7 yr–1, M2 (1.4–1.8) } 10–8
M
yr–1. It is suggested that MXB 1916-05 is the progenitor of the system MXB 1820-30 (M
2 = 0.1M,X 0.221,M
2 1.8 × 10–10
M
yr–1). 相似文献
12.
Infinite series expansions are obtained for the doubly averaged effects of the Moon and Sun on a high altitude Earth satellite, and the results used to interpret numerically integrated examples. New in this paper are: (1) both sublunar and translunar satellites are considered; (2) analytic expansions include all powers in the satellite and perturbing body semi-major axes; (3) the fact that retrograde orbits have more benign eccentricity behavior than direct orbits should be exploited for high altitude satellite systems; and (4) near circular orbits can be maintained with small expenditures of fuel in the face of an exponential driving force one forI
ab, whereI
b=180°–I
a andI
a is somewhat less than 39.2° for sublunar orbits and somewhat greater than 39.2° for translunar orbits.Nomenclature
a
semi-major axis
-
A
lk
coefficient defined in Equation (11)
-
B
lk
coefficient defined in Equation (24)
-
C
km
coefficient defined in Equation (25)
-
D, E, F
coefficients in Equations (38), (39)
-
e
eccentricity
-
H
k
expression defined in Equation (34)
-
expression defined in Equation (35)
-
I
inclination of satellite orbit on lunar (or solar) ring plane
-
J
2
coefficient of second harmonic of Earth's gravitational potential (1082.637×10–6
R
E
2
)
-
K
k, Lk, Mk
expressions in Section 4
-
expressions in Section 4
-
p=a(1–e
2)
semi-latus rectum
-
P
l
Legendre polynomial of degreel
-
q
argument of Legendre polynomial
-
radial distance of satellite
-
R
E
Earth equatorial radius (6378.16 km)
-
R, S, W
perturbing accelerations in the radial, tangential and orbit normal directions
- syn
synchronous orbit radius (42 164.2 km=6.6107R
E)
-
t
time
-
T
satellite orbital period
-
T
orbital period of perturbing body (Moon)
-
T
e
period of long periodic oscillations ine for |I|<I
a
-
T
s
synodic period
-
U
gravitational potential of lunar (or solar) ring
-
x, y, z
Cartesian coordinates of a satellite with (x, y) being the ring plane
-
coefficient defined in Equation (20)
-
average change in orbital element over one orbit (=a, e, I, , )
- 1,23
unit vectors in thex, y, z coordinate directions
-
r
,
s
,
w
unit vectors in the radial, tangential and orbit normal directions
- =+
angle along the orbital plane from the ascending node on the ring plane to the true position of the satellite
-
angle around the ring
-
gravitational constant times mass of Earth (3.986 013×105 km s–2)
-
gravitational constant times mass of Moon (or Sun)
-
m
gravitational constant times mass of Moon (/81.301)
-
s
gravitational constant time mass of Sun (332 946 )
-
ratio of the circumference of a circle to its diameter
-
radius of lunar (or solar) ring
-
m
radius of lunar ring (60.2665R
E)
-
s
radius of solar ring (23455R
E)
-
true anomaly
-
argument of perigee
- 0
initial value of
-
i
critical value of in quadranti(i=1, 2, 3, 4)
-
longitude of ascending node on ring plane
This work was sponsored by the Department of the Air Force. 相似文献
13.
C. A. Lindsey 《Solar physics》1977,52(2):263-281
Infrared continuum observations of the Sun at wavelengths between 10 and 30 show a nonisothermal response of the upper photosphere to compression waves associated with the five-minute oscillations. Observations were made with four broad-band filters with effective transmission wavelengths between 10 and 26 and with a 10 aperture. Further observations at submillimeter wavelengths with a 2 aperture did not resolve oscillatory fluctuations of five-minute period.Comparisons with velocity field data of Howard (1976) suggest that the relaxation time of the photosphere exceeds (300/2) seconds at the height of formation of the 26 continuum (5000Å 10-2). The photosphere reponds to 3 mHz oscillatory motion with considerably less compression than expected for simple acoustic modes in an adiabatically responsive atmosphere, confirming the evanescent character of the five-minute oscillations. 相似文献
14.
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
15.
The structure and evolution of a slow reaction front propagation into a cool, hydrogen rich shell above an inert core has been studied. It has been found that, during the evolution of the front, the total radiative luminosity drops from 104
L
to 10–4
L
in a time scale of the order of 109 yr. The burned up fraction of the fuel is found to be less than 1%. 相似文献
16.
An exact analysis of the effects of mass transfer on the flow of a viscous incompressible fluid past an uniformly accelerated vertical porous and non-porous plate has been presented on taking into account the free convection currents. The results are discussed with the effects of the Grashof number Gr, the modified Grashof number Sc, the Schmidt number Sc, and the suction parametera for Pr (the Prandtl number)=0.71 representating air at 20°C.Nomenclature
a
suction parameter
-
C
species concentration
-
C
species concentration at the free stream
-
g
acceleration due gravity
- Gc
modified Grashof number (vg*(C
–C
)/U
0
3
)
- Pr
Prandtl number (C
p/K)
-
T
temperature of the fluid near the plate
-
T
dimensionless temperature near the plate ((T-T
)/(T
-T
))
-
U(t)
dimensionless velocity of the plate (U/U
0)
-
v
normal velocity component
-
v
0
suction/injection velocity
-
x, y
coordinate along and normal to the plate
-
v
kinematic viscosity (/gr)
-
C
p
specific heat at constant pressure
-
C
w
species concentration at the plate
-
C
non-dimensional species concentration ((C-C
)/(C
w
-C
))
- Gr
Grashof number (g(T
w
-T
)/U
0
3
)
-
D
chemical molecular diffusivity
- K
thermal conductivity
- Sc
Schmidt number (/D)
-
T
w
temperature of the plate
-
T
free stream temperature
-
t
time variable
-
t
dimensionless time (tU
0
2
/)
-
U
0
reference velocity
-
u
velocity of the fluid near the plate
-
u
non-dimensional velocity (u/U
0)
-
v
dimensionless velocity (v/U
0)
-
v
0
non-dimensionalv
0
(v
0
/U0)=–at–1/2
-
y
dimensionless ordinate (yU
0/)
-
density of the fluid
-
coefficient of viscosity 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.
It is shown that X-ray radiation of neutron stars with magnetic fieldsB=1011–1013 G near cyclotron resonances=s
B
(s=1,2,...) is deeply affected by such quantum effects as electron-positron vacuum polarization (significant at V=3×1028
n
e
–1
(B/B
C
4)1, whereB
C
=4.4×1013G), the quantizing character of the magnetic field (significant atV=3 x 1028
n
e
–1
(B/B
c)41 whereB
c
=4.4 x 1013G), the non-harmonic character of the Landau levels, and the quantum recoil of electrons. The latter two factors shift the resonances by the frequency –s
2
B
(B/2B
c
)sin2, being the angle between the direction of radiation propagation and the magnetic field. IfVV
0 (for 1,V
0–1=(mc
2/2T)1/2), the normal mode (NM) polarizations, as well as the absorption coefficientk
1 of the extraordinary NM in the Doppler core of the first resonance (|–| B cos ), is only slightly affected by varyingb and/orV, whereas for the ordinary NM (at 1)k
2k
1
2[b + (3 + tan2–2V)2]k
1. For sufficiently largeb and/orV the quantum effects amplify resonant absorption of the ordinary NM at
B
, with spin-flip transitions playing a major role atb1+V
2. IfVV
0, the coefficientsk
1 andk
2 in the Doppler core of the resonance are of the same order and acquire some peculiar features (shifts, intersections, etc.), with the NM polarizations depending sharply on and being strongly non-orthogonal. AtVV
0,k
2=k
1(cos2 +B/2B
C
) and the polarizations are almost linear. Near high resonances (s2), as a rule,k
1,2(1 + b)
s–1
2s–3 i.e., absorption increases withb due to replacement of the thermal energy of the transverse motion of electron,T, by the magnetic energy
B
. The above effects should be taken into account for an interpretation of observational data on X-ray pulsars (e.g., Her X-1) and other X-ray sources associated with neutron stars. 相似文献
19.
The data on the spectrum of the cosmic-ray electron component near the earth, on the radio-spectra of radio-galaxies, quasars and the Crab Nebula, as well as the data pertaining to the X-ray spectrum of the cosmic background, all agree that the sources of cosmic-ray electrons (such as supernovae and galactic nuclei) inject particles characterized by a power spectrumN(E)=KE
–0, with 01.5–2.5. A mechanism is known in which the source emits a proton-nuclear component of cosmic rays with a spectrumN
n
(E)=K
n
E
–
n, n = + 2, =w
cr/(w–w
cr), wherew
cr is the cosmic-ray energy density in the source, andw=w
cr+w
n+w
turb, the total energy density. We obtain =2.5 in agreement with observations on the natural assumption that =0.5. Within the framework of the same model with some additional assumptions, the electrons in the source, as well as those ejected by the source, are shown to have a power-spectrum characterized with 0 n = + 2. Thus the model discussed gives an adequate spectrum for both the proton-nuclear and the electron components of cosmic rays. 相似文献
20.
N.Z. Scoville 《Astrophysics and Space Science》1999,266(1-2):149-155
Recent high resolution near infrared (HST-NICMOS) and mm-interferometric imaging have revealed dense gas and dust accretion disks in nearby ultra-luminous galactic nuclei. In the best studied ultraluminousIR galaxy, Arp 220, the 2m imaging shows dust disks in both of the merging galactic nuclei and mm-CO line imaging indicates molecular gasmasses 109M for each disk. The two gas disks in Arp 220 are counterrotating and their dynamical masses are 2×109
M
, that is, only slightly largerthan the gas masses. These disks have radii 100 pc and thickness 10-50 pc. The high brightness temperatures of the CO lines indicatethat the gas in the disks has area filling factors 25-50% and mean densitiesof 104 cm-3. Within these nuclear disks, the rate of massive star formation is undoubtedly prodigious and, given the high viscosity of the gas, there will also be high radial accretion rates, perhaps 10 M yr -1. If this inflow persists to very small radii, it is enough to feed even the highest luminosity AGNs. 相似文献