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1.
We employ annually averaged solar and geomagnetic activity indices for the period 1960??C?2001 to analyze the relationship between different measures of solar activity as well as the relationship between solar activity and various aspects of geomagnetic activity. In particular, to quantify the solar activity we use the sunspot number R s, group sunspot number R g, cumulative sunspot area Cum, solar radio flux F10.7, and interplanetary magnetic field strength IMF. For the geomagnetic activity we employ global indices Ap, Dst and Dcx, as well as the regional geomagnetic index RES, specifically estimated for the European region. In the paper we present the relative evolution of these indices and quantify the correlations between them. Variations have been found in: i) time lag between the solar and geomagnetic indices; ii) relative amplitude of the geomagnetic and solar activity peaks; iii) dual-peak distribution in some of solar and geomagnetic indices. The behavior of geomagnetic indices is correlated the best with IMF variations. Interestingly, among geomagnetic indices, RES shows the highest degree of correlation with solar indices.  相似文献   

2.
We present our B, V, Rc, and Ic observations of a \(3'.6 \times 3'\) field centered on the host galaxy of GRB 000926 (α2000.0=17h04m11s, \(\delta _{2000.0} = + 51^ \circ 47'9\mathop .\limits^{''} 8\)). The observations were carried out on the 6-m Special Astrophysical Observatory telescope using the SCORPIO instrument. The catalog of galaxies detected in this field includes 264 objects for which the signal-to-noise ratio is larger than 5 in each photometric band. The following limiting magnitudes in the catalog correspond to this limitation: 26.6 (B), 25.7 (V), 25.8 (R), and 24.5 (I). The differential galaxy counts are in good agreement with previously published CCD observations of deep fields. We estimated the photometric redshifts for all of the cataloged objects and studied the color variations of the galaxies with z. For luminous spiral galaxies with M(B)z～1.  相似文献   

3.
The type II solar radio burst recorded on 13 June 2010 by the Hiraiso Solar Observatory Radio Spectrograph was employed to estimate the magnetic-field strength in the solar corona. The burst was characterized by a well-pronounced band splitting, which we used to estimate the density jump at the shock and Alfvén Mach number using the Rankine–Hugoniot relation. We convert the plasma frequency of the type II burst into height [R] in solar radii using an appropriate density model, and then we estimated the shock speed [V s], coronal Alfvén velocity [V A], and the magnetic-field strength at different heights. The relative bandwidth of the band splitting was found to be in the range 0.2?–?0.25, corresponding to a density jump of X=1.44?–?1.56, and an Alfvén Mach number of M A=1.35?–?1.45. The inferred mean shock speed was on the order of V≈667 km?s?1. From the dependencies V(R) and M A(R) we found that the Alfvén speed slightly decreases at R≈1.3?–?1.5 R⊙. The magnetic-field strength decreases from a value between 2.7 and 1.7 G at R≈1.3?–?1.5 R⊙, depending on the coronal-density model employed. Our results are in good agreement with the empirical scaling by Dulk and McLean (Solar Phys. 57, 279, 1978) and Gopalswamy et al. (Astrophys. J. 744, 72, 2012). Our results show that the type II band-splitting method is an important tool for inferring the coronal magnetic field, especially when independent measurements are made from white-light observations.  相似文献   

4.
We report a detailed analysis of an interaction between two coronal mass ejections (CMEs) that were observed on 14?–?15 February 2011 and the corresponding radio enhancement, which was similar to the “CME cannibalism” reported by Gopalswamy et al. (Astrophys. J. 548, L91, 2001). A primary CME, with a mean field-of-view velocity of 669 km?s?1 in the Solar and Heliospheric Observatory (SOHO)/Large Angle Spectrometric Coronagraph (LASCO), was more than as twice as fast as the slow CME preceding it (326 km?s?1), which indicates that the two CMEs interacted. A radio-enhancement signature (in the frequency range 1 MHz?–?400 kHz) due to the CME interaction was analyzed and interpreted using the CME data from LASCO and from the Solar Terrestrial Relations Observatory (STEREO) HI-1, radio data from Wind/Radio and Plasma Wave Experiment (WAVES), and employing known electron-density models and kinematic modeling. The following results are obtained: i) The CME interaction occurred around 05:00?–?10:00 UT in a height range 20?–?25 R⊙. An unusual radio signature is observed during the time of interaction in the Wind/WAVES dynamic radio spectrum. ii) The enhancement duration shows that the interaction segment might be wider than 5 R⊙. iii) The shock height estimated using density models for the radio enhancement region is 10?–?30 R⊙. iv) Using kinematic modeling and assuming a completely inelastic collision, the decrease of kinetic energy based on speeds from LASCO data is determined to be 0.77×1023 J, and 3.67×1023 J if speeds from STEREO data are considered. vi) The acceleration, momentum, and force are found to be a=?168 m?s?2, I=6.1×1018 kg?m?s?1, and F=1.7×1015 N, respectively, using STEREO data.  相似文献   

5.
The 11-year modulation of cosmic-ray intensity is studied using the data from nine world-wide neutron monitoring station over the period 1965–1975. From this analysis the following relation among the modulated cosmic-ray intensityI, the relative sunspot numberR, the number of proton eventsN p and the geomagnetic indexA p has been derived which describes the long-term modulation of cosmic rays $$I = C - 10^{ - 3} (KR + 4N_P + 12A_P ),$$ whereC is a constant which depends on the rigidity of each station, andK is a coefficient related to the diffusion coefficient of cosmic rays and its transition in space. The standard deviation between the observed and calculated values of cosmic-ray intensity is about 5–9%. This relation has been explained by a generalization of the Simpson solar wind model which has been proved by the spherically symmetric diffusion-convection theory.  相似文献   

6.
The seasonal variation of the geomagnetic activity shows two sharp maxima (in March and September) and two broader minima (in June and December). It can only poorly be described by a double sine wave. The double phase wave of geomagnetic activity can be transformed - by vertical mirroring of the half year part between the maxima - into a single phase wave, which is represented well by a single sine function. This function is determined here for C i (the daily international character figure of geomagnetic activity) and for A p (the equivalent daily amplitude, based on K p, the geomagnetic planetary three-hour-range indices), for both in their ratios to the mean value over the year and then averaged over many years. To remove part of the irregularities the daily values of C i and A p were corrected for solar activity and reduced to quiet Sun circumstances. Mirroring back to the double phase function the geomagnetic variation is then represented by $$Ci({\text{or }}Ap) = Cm({\text{or }}Ap,m) - |A{\text{ sin}}(\lambda - \varphi )|$$ , in which m means the mirror value, A is the amplitude of the single sine curve, λ runs parallel to the Sun's longitude, ? is the phase constant and the bars indicate the absolute value. The data of the first maximum of the seasonal variation was found to vary between March 18 and 28 for different groups of years. The sharpness of the maxima may point out a resonance in the interaction between the solar wind and the magnetosphere. In the appendix the relation \(Ci = aR^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0em} 2}} + b\) (R being the relative sunspot number) is brought forward. The values of the parameter b through the eleven-year period reveal an increasing influence of sunspot-free regions towards the minimum.  相似文献   

7.
We compare the geoeffective parameters of halo coronal mass ejections (CMEs). We consider 50 front-side full-halo CMEs (FFH CMEs), which are from the list of Michalek, Gopalswamy, and Yashiro (Solar Phys. 246, 399, 2007), whose asymmetric-cone model parameters and earthward-direction parameter were available. For each CME we use its projected velocity [V p], radial velocity [V r], angle between cone axis and sky plane [γ] from the cone model, earthward-direction parameter [D], source longitude [L], and magnetic-field orientation [M] of its CME source region. We make a simple linear-regression analysis to find out the relationship between CME parameters and Dst index. The main results are as follows: i) The combined parameters [(V r D)1/2 and V r γ] have higher correlation coefficients [cc] with the Dst index than the other parameters [V p and V r]: cc=0.76 for (V r D)1/2, cc=0.70 for V r γ, cc=0.55 for V r, and cc=0.17 for V p. ii) Correlation coefficients between V r γ and Dst index depend on L and M; cc=0.59 for 21 eastern events [E], cc=0.80 for 29 western events [W], cc=0.49 for 17 northward magnetic-field events [N], and cc=0.69 for 33 southward magnetic-field events [S]. iii) Super geomagnetic storms (Dst≤?200 nT) only appear in the western and southward magnetic-field events. The mean absolute Dst values of geomagnetic storms (Dst≤?50 nT) increase with an order of E+N, E+S, W+N, and W+S events; the mean absolute Dst value (169 nT) of W+S events is significantly larger than that (75 nT) of E+N events. Our results demonstrate that not only do the cone-model parameters together with the earthward-direction parameter improve the relationship between CME parameters and Dst index, but also the longitude and the magnetic-field orientation of a FFH CME source region play a significant role in predicting geomagnetic storms.  相似文献   

8.
Theoretical electron-temperature-sensitive Mgix emission line ratios are presented forR I =I(443.96 )/I(368.06 ),R 2 =I(439.17 )/I(368.06 ),R 3 =I(443.37 )/I(368.06 ),R 4 =I(441.22 )/I(368.06 ), andR 5 =I(448.28 )/I(368.06 ). A comparison of these with observational data for a solar active region, obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals excellent agreement between theory and observation forR 1 throughR 4, with discrepancies that average only 9%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on boardSkylab. However in the case ofR 5, the theoretical and observed ratios differ by almost a factor of 2. This may be due to the measured intensity of the 448.28 line being seriously affected by instrumental effects, as it lies very close to the long wavelength edge of the SERTS spectral coverage (235.46–448.76 ).  相似文献   

9.
Theoretical ArXIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurateR-matrix calculations, are presented forR 1 =I(242.22 )/I(236.27 ),R 2 =I(210.46 )/I(236.27 ), andR 3 =I(248.68 )/I(236.27 ). Electron densities deduced from the observed values ofR 1,R 2, andR 3 for solar flares obtained with the NRL S082A slitless spectrograph on boardSkylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in CaXV, which is formed at a similar electron temperature to that of ArXIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios.  相似文献   

10.
Various solar wind forecasting methods have been developed during the past decade, such as the Wang?–?Sheeley model and the Hakamada?–?Akasofu?–?Fry Version 2 (HAFv2) model. Also, considerable correlation has been found between the solar wind speed v and the coronal hole (CH) area A M on the visible side of the Sun, showing quantitative improvement of forecasting accuracy in low CME activity periods (e.g., Vr?nak, Temmer, and Veronig, Solar Phys. 240, 315, 2007a). Properties of lower layers of the solar atmosphere are good indications of the subsequent interplanetary and geomagnetic activities. We analyze the SOHO/EIT 284 Å images and construct a new forecasting factor (Pch) from the brightness of the solar EUV emission, and a good correlation is found between the Pch factor and the 3-day-lag solar wind velocity (v) probed by the ACE spacecraft. The main difference between the Pch and A M factor is that Pch does not depend on the CH-boundary estimate and can reflect both the area and brightness of CH. A simple method of forecasting the solar wind speed near Earth in low CME activity periods is presented. Between Pch and v from 21 November until 26 December 2003, the linear correlation coefficient is R=0.89. For comparison we also analyze the data in the same period (DOY 25?–?125, 2005) as Vr?nak, Temmer, and Veronig (Solar Phys. 240, 315, 2007a), who used the CH areas A M for predicting the solar wind parameters. In this period the correlation coefficient between Pch and v is R=0.70, whereas for A M and v the correlation coefficient is R=0.62. The average relative difference between the calculated and the observed values is $\overline{|\delta|}\approx 12.15\%Various solar wind forecasting methods have been developed during the past decade, such as the Wang – Sheeley model and the Hakamada – Akasofu – Fry Version 2 (HAFv2) model. Also, considerable correlation has been found between the solar wind speed v and the coronal hole (CH) area A M on the visible side of the Sun, showing quantitative improvement of forecasting accuracy in low CME activity periods (e.g., Vršnak, Temmer, and Veronig, Solar Phys. 240, 315, 2007a). Properties of lower layers of the solar atmosphere are good indications of the subsequent interplanetary and geomagnetic activities. We analyze the SOHO/EIT 284 ? images and construct a new forecasting factor (Pch) from the brightness of the solar EUV emission, and a good correlation is found between the Pch factor and the 3-day-lag solar wind velocity (v) probed by the ACE spacecraft. The main difference between the Pch and A M factor is that Pch does not depend on the CH-boundary estimate and can reflect both the area and brightness of CH. A simple method of forecasting the solar wind speed near Earth in low CME activity periods is presented. Between Pch and v from 21 November until 26 December 2003, the linear correlation coefficient is R=0.89. For comparison we also analyze the data in the same period (DOY 25 – 125, 2005) as Vršnak, Temmer, and Veronig (Solar Phys. 240, 315, 2007a), who used the CH areas A M for predicting the solar wind parameters. In this period the correlation coefficient between Pch and v is R=0.70, whereas for A M and v the correlation coefficient is R=0.62. The average relative difference between the calculated and the observed values is . Furthermore, for the ten peaks during the analysis period, Pch and v show a correlation coefficient of R=0.78, and the average relative difference between the calculated and the observed peak values is . Moreover, the Pch factor can eliminate personal bias in the forecasting process, which existed in the method using CH area as input parameter, because CH area depends on the CH-boundary estimate but Pch does not. Until now the CH-boundary could not be easily determined since no quantitative criteria can be used to precisely locate CHs from observations, which led to differences in forecasting accuracy.  相似文献   

11.
Gnevyshev [Solar Phys. 1, 107, 1967] showed that in solar cycle 19 (1954 –1965), the coronal line half-yearly average intensity at 5303 Å (green line) had actually two maxima, the first one in 1957 and the second in 1959–1960. In the present communication, the structures at solar maxima were reexamined in detail. It was noted that the two-peak structure of solar indices near sunspot (Rz) maxima was only a crude approximation. On a finer time scale (monthly values), there were generally more than three peaks, with irregular peak separations in a wide range of ～12± 6 months. The sequences were seen simultaneously (within a month or two) at many solar indices (notably the 2800 MHz radio flux) at and above the photosphere, and these can be legitimately termed ‘Gnevyshev peaks’ and ‘Gnevyshev gaps’. The open magnetic flux emanating from the Sun showed this sequence partially, some peaks matching, others not. In interplanetary space, the interplanetary parameters N (number density), V (solar wind speed), B (magnetic field) showed short-time peak structures but mostly not matching with the Rz peaks. Geomagnetic indices (aa, Dst) had peaked structures, which did not match with Rz peaks but were very well related to V and B, particularly to the product VB. The cosmic ray (CR) modulation also showed peaks and troughs near sunspot maximum, but the matching with Rz peaks was poor. Hence, none of these can be termed Gnevyshev peaks and gaps, particularly the gap between aa peaks, one near sunspot maximum and another in the declining phase, as this gap is qualitatively different from the Gnevyshev gap in solar indices.  相似文献   

12.
A series of hydrodynamical models of type-II supernova outbursts (SNII) has been calculated. Approximate relations connecting the total outburst energy ε, the mass of envelope ejectedM, the presupernova radiusR, and the amount of ionizing quanta radiated by the supernovaeN H with such values as the duration of the light curve plateau Δt, and absolute magnitude in the wavelength bandV and photospheric velocityU PH observed near the middle of the plateau have been established. Advantage has been taken of the relations to obtain a preliminary evaluation for the characteristics of the average SN II: ε=7×1050 erg,M=6M ⊙,R=500R ⊙,N H=2×1058. The SNIIs with plateau-like light curves seem to be accounted for by thermonuclear explosions of degenerate cores of red giant stars and result in a total disruption of the star without any stellar remnant. To the contrary, SNIIs with linear light curves have substantially different properties (in particular, they throw considerably less massive envelopes off). These SNII must signify the birth of collapsed objects—neutron stars (pulsars) or black holes.  相似文献   

13.
Theoretical Ca X electron temperature sensitive emission line ratios, derived using electron excitation rates interpolated from accurateR-matrix calculations, are presented forR 1 =I(419.74 )/I(574.02 ,),R 2 =I(411.65 )/I(574.02 ),R 3 =I(419.74 )/I(557.75 ), andR 4 =I(411.65 )/I(557.75 ). A comparison of these with observational data for three solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on boardSkylab, reveals good agreement between theory and observation forR 1 andR 3 in one event, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, in the other flares the observed values ofR 1 –R 4 are much larger than the theoretical high-temperature limits, which is probably due to blending of the 419.74 line with Civ 419.71 , and 411.65 with possibly Ciii 411.70 .  相似文献   

14.
Coronal yellow line emission was observed by the Lyot coronagraph at the Abastumani Astrophysical Observatory. Line intensity is I = 45 erg cm?2 s?1 sr?1 Å?1, its half-width Δλ = 1.3 Å, electronconcentration n e = 7.5 × 109 cm?3.  相似文献   

15.
Based on observations of SN 1999em, we determined the physical parameters of this supernova using hydrodynamic calculations including nonequilibrium radiative transfer. Taking the distance to SN 1999em estimated by the expanding photosphere method (EPM) to be D = 7.5 Mpc, we found the parameters of the presupernova: radius R = 450R⊙, mass M = 15M⊙, and explosion energy E = 7 × 1050 erg. For the distance D = 12 Mpc determined from Cepheids, R, M, and E must be increased to the following values: R = 1000R⊙, M = 18M⊙, and E = 1051 erg. We show that one cannot restrict oneself to using the simple analytical formulas relating the supernova and presupernova parameters to obtain reliable parameters for type-IIP presupernovae.  相似文献   

16.
Published photoelectric measurements over a wide wavelength range (0.36–18 µm) are used to study the continuum spectrum of the star Θ1 Ori C. The model that assumes the following three radiation sources is consistent with observations: (1) a zero-age main-sequence O7 star (object 1) of mass M 1=20M ⊙, radius R 1=7.4R ⊙, effective temperature T 2=37 000 K, and absolute bolometric magnitude $M\mathop {bol}\limits^1 = - 7\mathop .\limits^m 7$ ; (2) object 2 with M 2=15M ⊙, R 2=16.2R ⊙, T 2=4000 K, and $M\mathop {bol}\limits^2 = - 5\mathop .\limits^m 1$ ; and (3) object 3 with R 310 700 R ⊙, T 3=190 K, and $M\mathop {bol}\limits^3 = - 0\mathop .\limits^m 6$ . The visual absorption toward the system is $A_V = 0\mathop .\limits^m 95$ and obeys a normal law. The nature of objects 2 and 3 has not been elucidated. It can only be assumed that object 2 is a companion of the primary star, its spectral type is K7, and it is in the stage of gravitational contraction. Object 3 can be a cocoon star and a member of the system, but can also be a dust envelope surrounding the system as a whole.  相似文献   

17.
The physical and geometrical parameters of the individual components of the binary system Hip11253 (HD14874) are estimated. We used the method described in previous papers, which consists in getting the best fit between the entire observational spectral energy distribution of the system and the synthetic ones, created from model atmospheres. The parameters of the individual components of the system are derived as: T eff a = 6030 ± 100 K, T eff b = 4470 ± 130 K, log g a = 4.27 ± 0.13, log g b = 4.04 ± 0.13, R a = 1.22 ± 0.09R⊙, R b = 1.32 ± 0.20R⊙, with the G0 and K4.5 spectral types for the primary and secondary components, respectively. The synthetic magnitudes of both components were calculated using the Johnson-Cousins, Strömgren, and Tycho photometrical systems. Finally the formation and evolution of the system was discussed.  相似文献   

18.
In this paper we consider asymptotic behavior of a hybrid action of f(R) gravity model which proposed by Saffari and Rahvar (2008), in the Solar system scale, which can explain Pioneer anomalous acceleration. We use the resultant weak field gravitational potential which comes from the hybrid action to test its impacts on the Solar system dynamics, by comparing theoretical precession of perihelion of a test particle, , with corrections to the standard Newtonian-Einstenian precessions of perihelia of some planets, which recently estimated by [Pitjeva, 2005a], [Pitjeva, 2005b], [22] and [23]. Here we show that the asymptotic behavior of hybrid action is in more accordance with observation relative to the other modifications such as power law and logarithmic corrections (Iorio, 2008). We also show that an extra additional lensing of the prediction of General Relativity is reproduced. Finally we consider the stability condition of planetary orbits in the presence of the hybrid action.  相似文献   

19.
Lunar electric fields,surface Potential and Associated Plasma Sheaths   总被引：1，自引：0，他引：1  
This paper reviews the electric field environment of the Moon. Lunar surface electric potentials are reported as follows: Solar Wind - Dayside: øo + 10 to + 18 V Solar Wind - Terminator: øo ç ? 10 to ? 100 V Electron and ion densities in the plasma sheath adjacent to each surface potential regime are evaluated and the corresponding Debye length estimated. The electric fields are then approximated by the surface potential over the Debye length. The results are: Solar Wind - Dayside: Eo ? 10 V m?1 outward Solar Wind - Terminator: Eo ç 1 to 10 V m?1 inward These fields are all at least 3 orders of magnitude higher than the pervasive solar wind electric field; however they are confined to within a few tens of meters of the lunar surface.  相似文献   

20.
Three three-component (bulge, disk, halo) model Galactic gravitational potentials differing by the expression for the dark matter halo are considered. The central (bulge) and disk components are described by the Miyamoto–Nagai expressions. The Allen–Santillán (I), Wilkinson–Evans (II), and Navarro–Frenk–White (III) models are used to describe the halo. A set of present-day observational data in the range of Galactocentric distances R from 0 to 200 kpc is used to refine the parameters of thesemodels. For the Allen–Santillán model, a dimensionless coefficient γ has been included as a sought-for parameter for the first time. In the traditional and modified versions, γ = 2.0 and 6.3, respectively. Both versions are considered in this paper. The model rotation curves have been fitted to the observed velocities by taking into account the constraints on the local matter density ρ ⊙ = 0.1 M ⊙ pc?3 and the force K z =1.1/2πG = 77 M ⊙ pc?2 acting perpendicularly to the Galactic plane. The Galactic mass within a sphere of radius 50 kpc, M G (R ≤ 50 kpc) ≈ (0.41 ± 0.12) × 1012 M ⊙, is shown to satisfy all three models. The differences between the models become increasingly significant with increasing radius R. In model I, the Galactic mass within a sphere of radius 200 kpc at γ = 2.0 turns out to be greatest among the models considered, M G (R ≤ 200 kpc) = (1.45 ±0.30)× 1012 M ⊙, M G (R ≤ 200 kpc) = (1.29± 0.14)× 1012 M ⊙ at γ = 6.3, and the smallest value has been found in model II, M G (R ≤ 200 kpc) = (0.61 ± 0.12) × 1012 M ⊙. In our view, model III is the best one among those considered, because it ensures the smallest residual between the data and the constructed model rotation curve provided that the constraints on the local parameters hold with a high accuracy. Here, the Galactic mass is M G (R ≤ 200 kpc) = (0.75 ± 0.19) × 1012 M ⊙. A comparative analysis with the models by Irrgang et al. (2013), including those using the integration of orbits for the two globular clusters NGC 104 and NGC 1851 as an example, has been performed. The third model is shown to have subjected to a significant improvement.  相似文献   

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