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1.
Using the cosmic ray sidereal and anti-sidereal diurnal variations observed underground in London and Hobart during the period 1958–1983, it is demonstrated that: (1) the phase changes of the apparent sidereal diurnal variation observed only in the Northern Hemisphere cannot be attributed to the change of the heliomagnetospheric modulation of galactic cosmic ray anisotropy caused by the polarity reversal of the solar magnetic field, but that they are due to the fluctuation of the spurious sidereal variation produced from the anisotropy responsible for the solar semi-diurnal variation; (2) the spurious sidereal variation can be eliminated from the apparent variation by using the observed anti-sidereal diurnal variation; and (3) after the elimination, the sidereal diurnal variations in the Northern and Southern Hemispheres almost coincide with each other and are stationary throughout the period, regardless of the polarity reversal of the heliomagnetosphere. The origin of the corrected sidereal variation is discussed.  相似文献   

2.
In the previous paper (Nagashima et al., 1982), we have reported the yearly averaged modulation of galactic cosmic ray anisotropy in the heliomagnetosphere. In the present paper, we analyze the seasonal (annual) dependence of the modulation, using the frequency modulation method. The seasonal variation of the sidereal daily variation produced from the anisotropy is resolved into variations with proper sideband frequencies, such as solar and anti-sidereal variations. These side-band variations are predominant in the rigidity region of 102 ～' 103 GV and show the following characteristics.(1) Being similar to the average sidereal variation, they are strongly dependent on the polarity state (‘positive’ or ‘negative’) of the heliomagnetosphere.(2) The side-band variations with frequencies lower than the sidereal frequency (366 cycle/year) generally predominate over those with higher frequencies. The most predominant variations are produced from the component of the uni-directional anisotropy projected to the Earth's rotation axis and could be observed as the solar and anti-sidereal diurnal variations.(3) If the flat neutral sheet of the heliomagnetosphere is replaced with the wavy neutral sheet, side-band variations in the positive state tend to diminish with the increase of the heliolatitudinal extent of the wavy neutral sheet, while those in the negative state almost retain their magnitude.(4) These variations depend also on the observation periods when the Earth is located either in the “toward” field or in the “away” field. This T-A dependence changes with the transition from the positive state to the negative and increases with the increase of the heliolatitudinal extent of the wavy neutral sheet. The most remarkable T-A dependence is observed in solar diurnal variation arising from the component of the unidirectional anisotropy projected to the Earth's rotation axis and can be used for the determination of the direction of the anisotropy.  相似文献   

3.
Data from underground muon telescopes in New Mexico and Bolivia are analyzed in sidereal time and anti-sidereal time to study anisotropies in the rigidity range 20 GV to a few 100s of GV. Using both vertical and North- and South-pointing telescopes in both hemispheres, a latitude range of 70°N–50°S is covered. The distribution of cosmic rays in the inner heliosphere gives rise to a diurnal variation in anti-sidereal time, and also produces a spurious contribution to the anisotropy in sidereal time. It is shown that the anti-sidereal variation is of the P21 type, having opposite phase in the Northern and Southern Hemispheres, and maximum amplitude at mid latitudes. The anti-sidereal data are used to correct the sidereal data, using the Nagashima method (Nagashima, Sakakibara, Fenton and Humble, 1985); the resulting corrected sidereal vectors for Northern Hemisphere telescopes have their sidereal maxima close to 3 h sidereal time, in reasonable agreement with sidereal data at higher energies from small air showers. The Nagashima correction also appears to eliminate effects due to the reversal of the Sun's polar magnetic field which show up in the unconnected sidereal data, and which also remain in corrected data using an alternative correction.  相似文献   

4.
We formulate the modulation of galactic anisotropy of cosmic rays caused by their orbital deflection in the heliomagnetosphere. According to the formulation, the average sidereal i-th harmonic daily variation (i = 1,2,…) produced from the anisotropy from an arbitrary direction can be expressed by a linear combination of three basic vectors for uni-directional anisotropy and five basic vectors for bi-directional anisotropy. These vectors are obtained by calculating trajectories of cosmic rays (20?104GV) in a model magnetosphere having Parker's Archimedian spiral structure with a flat or a wavy neutral sheet in either of two polarity states, one is called “Positive” state (away field in the northern space of the neutral sheet and toward field in the southern space) and the other is called “Negative” state (reversed state of the above). Among general characteristics of the sidereal daily variations, the most remarkable features are: (1) The observable variations in low rigidity (? 2000 GV) can be produced even from an uni-directional anisotropy in the direction of the Earth's rotation axis. These variations are strongly dependent on the polarity state, i.e., they are greater in the Positive state than in the Negative. (2) Those produced from the anisotropy in the Equatorial plane also show the polarity dependence but contrary to the previous case they are greater in the Negative state than in the Positive. Their magnitude in the former state is not so small even in the extremely low rigidity (～ 100 GV) as compared with that in high rigidity region. (3) These general characteristics are not altered by the introduction of the wavy neutral sheet or the magnetic irregularities, but the variations are affected more or less, depending on the heliolatitudinal extent of the wavy sheet or the degree of cosmic ray scattering with the irregularities, (4) Sidereal daily variation for the wavy sheet shows a toward-away field dependence similar to that of Swinson-type of solar origin, but the dependence is predominant in intermediate rigidity region (～ 500 GV), in marked contrast to that of solar origin. (5) Finally, whichever its direction may be, the uni-directional anisotropy produces the sidereal diurnal variation common to two conjugate stations in the Northern and Southern hemisphere. If there is any difference between the observed variations at the stations, it should be interpreted as being due to higher order anisotropy such as the bi-directional anisotropy.  相似文献   

5.
A radial anisotropy in the flux of cosmic rays in heliosphere was theoretically predicted by Parker and others within the framework of the diffusion–convection mechanism. The solar wind is responsible for sweeping out the galactic cosmic rays, creating a radial density gradient within the heliosphere. This gradient coupled with the interplanetary magnetic field induces a flow of charged particles perpendicular to the ecliptic plane which was measured and correctly explained by Swinson, and is hereafter referred as ‘Swinson flow’. The large area GRAPES-3 tracking muon telescope offers a powerful probe to measure the Swinson flow and the underlying radial density gradient of the galactic cosmic rays at a relatively high rigidity of ∼100 GV. The GRAPES-3 data collected over a period of six years (2000–2005) were analyzed and the amplitude of the Swinson flow was estimated to be (0.0644 ± 0.0008)% of cosmic ray flux which was an ∼80σ effect. The phase of the maximum flow was at a sidereal time of (17.70 ± 0.05) h which was 18 min earlier than the expected value of 18 h. This small 18 min phase difference had a significance of ∼6σ indicating the inherent precision of the GRAPES-3 measurement. The radial density gradient of the galactic cosmic rays at a median rigidity of 77 GV was found to be 0.65% AU−1.  相似文献   

6.
A method of reconstructing the declination of galactic cosmic ray anisotropy is described, and its results are presented. The method is based on analysis of delay distributions in symmetrically arranged detectors of an air shower array, and it represents a modification of the crossed telescopes method. It is shown that the declination of the true anisotropy vector is close to 60° (i.e., this vector lies approximately within the galactic plane). Because of this, the true degree of anisotropy of galactic cosmic rays is severalfold higher than the first harmonic of intensity in the sidereal time (the quantity measured directly), and it equals about 0.2%.  相似文献   

7.
R. H. Dicke 《Solar physics》1976,47(2):475-515
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8.
We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the solar wind velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of 23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent solar wind velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the solar wind velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the solar wind velocity V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.  相似文献   

9.
J. L. Snider 《Solar physics》1983,84(1-2):377-387
We have used an atomic-beam resonance-scattering technique applied to the 7699 Å solar potassium absorption line to make an absolute spectroscopic determination of the solar equatorial rotation rate. To our knowledge this is a new method which has not previously been used for studying solar rotation. Our measurements were made during 1979–82, initially with a permanent apparatus at Oberlin College and more recently with a portable apparatus installed at the Snow Telescope on Mt. Wilson. After carefully allowing for possible systematic errors, we conclude that the solar sidereal equatorial rotation rate is 13.8 ± 0.3 deg day#X2212;1 and that it has not varied significantly over the period of our observations.  相似文献   

10.
Measurements of the sidereal daily variation of the muon intensity at a depth of 60 m.w.e. have been carried out in London using telescopes inclined at 70° to the zenith for the period 1972 to the present. The direction of maximum sensitivity for these telescopes lies in the Earth's equatorial plane and the asymptotic directions of look at the boundary of the heliosphere have been determined by integrating the equation of motion of the primary particles in a model interplanetary magnetic field. In this way the measured sidereal variation can be related to the cosmic ray intensity distribution in interstellar space. It is shown that the observational data are consistent with an axially symmetric intensity distribution of the form ΔI = 0.09 (1 + cosα) % where ΔI is the direction from the mean intensity and α is measured from the direction of maximum intensity which lies at 1Π = 250° bΠ = ?60°. The most likely interpretation of this result is that the axis of this distribution corresponds to the local direction of the interstellar magnetic field and that the cosmic rays have a bulk streaming motion of 65±15 km s?1 along the field direction.  相似文献   

11.
Abstract— Previous studies have shown that the Kapoeta howardite, as well as several other meteorites, contains excess concentrations of cosmogenic Ne in the darkened, solar-irradiated phase compared to the light, non-irradiated phase. The two explanations offered for the nuclear production of these Ne excesses in the parent body regolith are either from galactic cosmic-ray proton (GCR) irradiation or from a greatly enhanced flux of energetic solar “cosmic-ray” protons (SCR), as compared to the recent solar flux. Combining new isotopic data we obtained on acid-etched, separated feldspar from Kapoeta light and dark phases with literature data, we show that the cosmogenic 21Ne/22Ne ratio of light phase feldspar (0.80) is consistent with only GCR irradiation in space for ～3 Ma. However, the 21Ne/22Ne ratio (0.68) derived for irradiation of dark phase feldspar in the Kapoeta regolith indicates that cosmogenic Ne was produced in roughly equal proportions from galactic and solar protons. Considering a simple model of an immature Kapoeta parent body regolith, the duration of this early galactic exposure was only ～3–6 Ma, which would be an upper limit to the solar exposure time of individual grains. Concentrations of cosmogenic 21Ne in pyroxene separates and of cosmogenic 126Xe in both feldspar and pyroxene are consistent with this interpretation. The near-surface irradiation time of individual grains in the Kapoeta regolith probably varied considerably due to regolith mixing to an average GCR irradiation depth of ～10 cm. Because of the very different depth scales for production of solar ～Fe tracks, SCR Ne, and GCR Ne, the actual regolith exposure times for average grains probably differed correspondingly. However, both the SCR 21Ne and solar track ages appear to be longer because of enhanced production by early solar activity. The SCR/GCR production ratio of 21Ne inferred from the Kapoeta data is larger by a at least a factor of 10 and possibly as much as a factor of ～50 compared to recent solar particle fluxes. Thus, this study indicates that our early Sun was much more active and emitted a substantially higher flux of energetic (>10 MeV/nucleon) protons.  相似文献   

12.
The space density of life-bearing primordial planets in the solar vicinity may amount to ～8.1×104?pc?3 giving total of ～1014 throughout the entire galactic disk. Initially dominated by H2 these planets are stripped of their hydrogen mantles when the ambient radiation temperature exceeds 3?K as they fall from the galactic halo to the mid-plane of the galaxy. The zodiacal cloud in our solar system encounters a primordial planet once every 26 My (on our estimate) thus intercepting an average mass of 103 tonnes of interplanetary dust on each occasion. If the dust included microbial material that originated on Earth and was scattered via impacts or cometary sublimation into the zodiacal cloud, this process offers a way by which evolved genes from Earth life could become dispersed through the galaxy.  相似文献   

13.
S.V.M. Clube  W.M. Napier 《Icarus》1985,62(3):384-388
The observed properties of the long-period comet system, and its periodic disturbance by galactic forces manifesting as terrestrial impact episodes, may be indicative of a comet capture/escape cycle as the Solar System orbits the Galaxy. A mean number density of comets in molecular clouds of ～10?1±1 AU?3 is implied. This is sufficient to deplete metals from the gaseous component of the interstellar medium, as observed, but leads to the problem of how stars are formed nevertheless with solar metal abundances. Formation of comets prior to stars in dense systems of near-zero energy may be indicated, and isotope signatures in cometary particles may be diagnostic of conditions in young spiral arm material.  相似文献   

14.
Abstract— The mineralogical and chemical characteristics of the Didwana‐Rajod chondrite are described. The mean mineral composition is found to be olivine (Fo83.2) and pyroxene (En83.5Wo0.7Fs15.8), and feldspar is mainly oligoclase. Oxygen isotopic analysis shows δ18O = +3.8%0 and δ17O = +2.59%0. The nitrogen content of Didwana‐Rajod is ～2 ppm with δ15N ? 3.4%0. Based on microscopic, chemical, isotopic and electron probe microanalysis, the meteorite is classified as an H5 chondrite. Cosmogenic tracks, radionuclides and the isotopic composition of rare gases were also measured in this meteorite. The track density in olivines varies in a narrow range with an average value of (6.5 ± 0.5) × 105/cm2 for four spot samples taken at the four corners of the stone. The cosmic‐ray exposure age based on neon and argon is 9.8 Ma. 22Na/26Al ? 0.94 is lower than the solar‐cycle average value of ～1.5 and is consistent with irradiation of the meteoroid to lower galactic cosmic‐ray fluxes as expected at the solar maximum. The track density, rare gas isotopic ratios, 60Co activity and other radionuclide data are consistent with a preatmospheric radius of ～15 cm, corresponding to a mass of ～50 kg. The cosmogenic properties are consistent with a simple exposure history in interplanetary space.  相似文献   

15.
Adding the angular velocity of sidereal solar rotation and the apparent rotational effect of the Earth's revolution vectorially, a new synodic solar rotation vector has been obtained. The sidereal and synodic solar rotation axes (and equators) are separated. Using the known parameters of the Earth's orbital motion, the synodic rotation angular velocity and the inclination of the synodic equator, the corresponding sidereal rotation parameters have been calculated (ω1 = 2.915 × 10#X2212;6 rad s#X2212;1 and i 1 = 6.076). Various linear rotational velocities at the solar globe are briefly described.  相似文献   

16.
We present a further investigation of the periodogram resulting from the photometric data by Rodríguez et al. (1997) for comet C/1995 O1 Hale–Bopp and interpret that the main period in the data is 11.23 ± 0.01 h, but not 7.19 days. The latter is now attributed to an alias of the 11.23-h period. Assuming that the periodicity observed in the photometry is the solar day, the 11.23-h period is consistent with estimates of the sidereal rotation period by Farnham et al. (1998), and Jorda et al. (1997–1999) provided that the obliquity of the comet‘s equatorial plane to its orbital plane is larger than 75° and 80°, respectively. This result is in agreement with estimates of the obliquity by Sekanina (1997–1999) and Jorda et al. (1998). A weaker periodic signal in the light curve could be 5.48 ± 0.01 h, but we suggest that this is an alias of a 3.25 ± 0.01 h period of unknown origin. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
A sample of O- and B-type stars with Hipparcos astrometric data, ages computed from Strömgren photometry and radial velocities, has been used to characterize the structure, age and kinematics of the Gould Belt system. The local spiral structure of our galaxy is determined from this sample, and also from a sample of Hipparcos Cepheid stars. The Gould Belt, with an orientation with respect to the galactic plane ofi G = 16-22° and ΩG =275-295°, extends up to a distance of 600 pc from the Sun. Roughly the 60-65% of the O and B stars younger than 60 Myr in the solar neighbourhood belong to this structure. Our results indicate that the kinematical behaviour of this system is complex, with an expansion motion in the solar neighbourhood (R<300 pc).In the frame of the Lin's theory, and analysing the O and B stars further than 600 pc and the Cepheids, we found a galactic spiral structure characterized by a 4-arm spiral pattern with the Sun located atψ⊙ = 350-355 ± 30° – near the Sagittarius-Carina arm– and outside the corotation circle. The angular rotation speed of the spiral pattern was found to be Ωp = 31-32 ± 4 kms-1 kpc-1.  相似文献   

18.
A quasi-periodic component was found at the maximum of the X-ray light curve for the June 10, 1990 solar flare detected by the Granat observatory. The pulsation period was 143.2±0.8 s. The intensity of the pulsing component is not constant; the maximum amplitude of the pulsations is ～5% of the total flare intensity. An analysis of the data showed the characteristic size of the magnetic loop responsible for these pulsations to be ～(1–3)×1010 cm.  相似文献   

19.
Summary In this paper the results of the research of the stars proper motions Trapezium components are reported. They are: the galactic coordinates of the solar aprx and the Sun velocity (L ⊙=43±18°,B ⊙=+28±13°,V ⊙=13±4 km s−1), the dispersion of peculiar velocities in the direction of the galactic coordinates for the above mentioned stars (σ l =±11 km s−1, σ b =±7 km s−1).The attained accuracy of the proper motions (±0.005″ yr−1) is shown to be insufficient to the study of internal space motions in these systems. At present the work to increase the relative proper motions accuracy for multiple system components and to improve reductions from the relative to absolute proper motions, is being carried out in the Main Astronomical Observatory (Academy of Sciences of the Ukrainian SSR). The new catalogue of the AGK3 stars is composed now in the vicinity of the galactic equator in order to improve reductions from the relative to absolute proper motions. The r.m.s. errors of the proper motions, obtained in the AGK3 system, are ±0.005″ yr−1.  相似文献   

20.
Abstract— Glass-rich separates were prepared from a sample of the basaltic lunar meteorite EET87521 rich in dark glass. Noble gas isotopic abundances and 26Al and 10Be activities were measured to find out whether shock effects associated with lunar launch helped to assemble these phases. Similar 10Be and 26Al activities indicate that all materials in EET87521 had a common exposure history in the last few million years before launch. However, the glass contains much higher concentrations of trapped gases and records a much longer cosmic-ray exposure, 100 Ma–150 Ma, in the lunar regolith than does the bulk sample. The different histories show that the glass existed long before the ejection of EET87521. The trapped 40Ar/36Ar ratio of 1.6 ± 0.1 implies that the lunar exposure that produced most of the stable cosmogenic noble gases began 500 Ma ago. Cosmogenic and trapped noble gas components correlate strongly in various temperature-release fractions and phases of EET87521, which is probably because the glass contains most of the gas. The trapped solar ratios, 20Ne/22Ne = 12.68 ± 0.20 and 36Ar/38Ar = 5.24 ± 0.05 can be understood as resulting from a mixture consisting of ～60% solar wind and 40% solar energetic particles (SEP). All EET87521 phases show a 40K-40Ar gas retention age of ～3300 Ma, which is in the range of typical lunar mare basalts.  相似文献   

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