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1.
New theoretical emission line ratios for the Be-sequence ions Mgix and Sixi are presented. A comparison with observational data for two solar flares and an active region loop obtained with the Harvard EUV spectrometer and NRL XUV spectroheliograph aboard Skylab reveals that these plasmas are in ionization equilibrium at coronal temperatures. Unfortunately most of the density diagnostics are not particularly useful under solar plasma conditions, as they vary only slightly over the electron density range 108–1013cm–3. However the Sixi ratioI(3 P e 2 -3 P o 2)/I(3 P o 1 –1 S e 0) is density sensitive in the range 108 to 1010cm–3, which is representative of electron densities found in solar active regions or small flares.  相似文献   

2.
Since its launch on March 8, 1967, the OSO-III has continuously observed solar and cosmic X-rays over the 7.7–210 keV range. The sun emits many impulsive X-ray bursts having fluxes several orders of magnitude above the background level of 8 × 10–9 ergs(cm2-sec)–1 at 7.7 keV and characteristic times on the order of 5 min. Ninety-five such events having fluxes >3 × 10–5 ergs(cm2-sec)–1 were detected in the period from March 8 to June 15, 1967. The cosmic X-ray source Lupus XR-1 has been observed to have a power law spectral form and no significant time variations over a 40-day period. Upper limits have been obtained on the hard X-ray flux of the peculiar galaxy M 87.  相似文献   

3.
A model of solar flare is proposed, taking into account the high temperature (109K) produced by the shock wave generated by the hydromagnetic wave at the junction of sunspot and the area just outside it and subsequent explosive hydrogen burning, producing the desired 1028–29 ergs of a solar flare.  相似文献   

4.
Stanley F. Dermott 《Icarus》1979,37(1):310-321
If the orbital resonances in the Jovian and Saturnian satellite systems are the result of orbital evolution due to tidal dissipation then the present rates of energy dissipation (Edot) are >2 × 1020 ergs sec?1 (Jupiter) and ?2 × 1016 ergs sec?1 (Saturn). These values of Edot can be accounted for if the planets have rocky cores with volumes equal to those suggested by current models of the interiors and if the material of these cores is both solid and imperfectly elastic (Qe ～ 34). The calculated values of Qe are not strongly dependent on either the rigidity of the core or the densities of the core and the mantle. Thus, these quantities need not be known precisely. It may be significant that approximately the same value of Qe is needed for all the major planets (Jupiter, Saturn, and Uranus) even though the values of Edot for these planets differ by a factor greater than 104.  相似文献   

5.
The Faraday rotation of a radio source (Pioneer 6) occulted by the solar corona has been measured by Levy et al. (1969). During the course of these measurements, three large-scale transient phenomena were observed. These events were preceded by subflares and class 1 flares. These transient events are interpreted as evidence for a coronal magnetic bottle at 10 R ⊙. The velocity of propagation for the disturbance is set at 200 km/sec; the dimension of the region, 10 R ⊙; field strength at 10 R ⊙, 0.02 G; particle density, 2.0 × 104/cm3; Alfvén speed, 320 km/sec. From the nature of the observations and the lack of related effects from similar flares on the interplanetary sector pattern observed at 1 AU, it is suggested that such coronal magnetic bottles expand to perhaps 10–30 R ⊙ and then contract to a few solar radii. Such a phenomena is evidence for an expansion of the corona with a sub-Alfvénic velocity. It is further suggested that such magnetic bottles may be important in the storage and diffusion of solar generated cosmic ray particles. NAS-NRC Postdoctoral Resident Research Associate.  相似文献   

6.
A major solar flare on 15 November, 1991 produced a striking perturbation in the position and shape of the sunspot related most closely to the flare. We have studied these perturbations by use of the aspect-sensor images from the Soft X-ray Telescope on board YOHKOH, and with ground-based data from the Mees Solar Observatory. The perturbation occurred during the impulsive phase of the flare, with a total displacement on the order of 1 arc sec. The apparent velocity of approximately 2 km s–1 exceeds that typically reported for sunspot proper motions even in flare events. We estimate that the magnetic energy involved in displacing the sunspot amounted to less than 4 × 1030 ergs, comparable to the radiant energy from the perturbed region. Examination of the Mees Observatory data shows that the spot continued moving at lower speed for a half-hour after the impulsive phase. The spot perturbation appears to have been a result of the coronal restructuring and flare energy release, rather than its cause.  相似文献   

7.
Hot regions in solar flares produce X-radiation and microwaves by thermal processes. Recent X-ray data make it possible to specify the temperature and emission measure of the soft X-ray source, by using, for instance, a combination of the 1–8 Å (peak response at about 2 keV) and the 0.5–3 Å (peak response at about 5 keV) broad-band photometers. The temperatures and emission measures thus derived satisfactorily explain the radio fluxes, within systematic errors of about a factor of 3. Comparison of 15 events with differing parameters shows that a hot solar flare region has an approximately isothermal temperature distribution. The time evolution of the correlation in a single event shows that the hot material originates in the chromosphere, rather than the corona. The density must lie between 1010 and 2 × 1011 cm–3. For an Importance 1 flare, this implies a stored energy of roughly 2 x 1030-1029 ergs. A refinement of the data will enable us to choose between conductive and radiative cooling models.  相似文献   

8.

We have statistically analyzed a set of 115 low frequency (Deca-Hectometer wavelengths range) type II and type III bursts associated with major Solar Energetic Particle (SEP: Ep?>?10 MeV) events and their solar causes such as solar flares and coronal mass ejections (CMEs) observed from 1997 to 2014. We classified them into two sets of events based on the duration of the associated solar flares:75 impulsive flares (duration <?60 min) and 40 gradual flares (duration >?60 min).On an average, the peak flux (integrated flux) of impulsive flares?×?2.9 (0.32 J m?2) is stronger than that of gradual flares M6.8 (0.24 J m?2). We found that impulsive flare-associated CMEs are highly decelerated with larger initial acceleration and they achieved their peak speed at lower heights (??27.66 m s?2 and 14.23 Ro) than the gradual flare-associated CMEs (6.26 m s?2 and 15.30 Ro), even though both sets of events have similar sky-plane speed (space speed) within LASCO field of view. The impulsive flare-associated SEP events (Rt?=?989.23 min: 2.86 days) are short lived and they quickly reach their peak intensity (shorter rise time) when compared with gradual flares associated events (Rt?=?1275.45 min: 3.34 days). We found a good correlation between the logarithmic peak intensity of all SEPs and properties of CMEs (space speed: cc?=?0.52, SEcc?=?0.083), and solar flares (log integrated flux: cc?=?0.44, SEcc?=?0.083). This particular result gives no clear cut distinction between flare-related and CME-related SEP events for this set of major SEP events. We derived the peak intensity, integrated intensity, duration and slope of these bursts from the radio dynamic spectra observed by Wind/WAVES. Most of the properties (peak intensity, integrated intensity and starting frequency) of DH type II bursts associated with impulsive and gradual flare events are found to be similar in magnitudes. Interestingly, we found that impulsive flare-associated DH type III bursts are longer, stronger and faster (31.30 min, 6.43 sfu and 22.49 MHz h?1) than the gradual flare- associated DH type III bursts (25.08 min, 5.85 sfu and 17.84 MHz h?1). In addition, we also found a significant correlation between the properties of SEPs and key parameters of DH type III bursts. This result shows a closer association of peak intensity of the SEPs with the properties of DH type III radio bursts than with the properties DH type II radio bursts, atleast for this set of 115 major SEP events.

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9.
On the basis of the hydrodynamical equations of a two-component gas (photons and hydrogen with coupling via Thomson scattering) in the recombination era of the Universe (standard model), the evolution of the density perturbations up to second order are calculated. It is shown, that the generated second-order amplitudes of the density fluctuations of the matter reach values of the same order as the first-order amplitudes within only one tenth of the expansion time for fluctuations with wavelengths corresponding to 107 M . Upper limits in the density fluctuations (for the gravitationally instable modes) up to which first-order calculations are valid, are given. This calculation indicates that the linear perturbation analysis is very restricted, especially at wavelengths near the lower limit of the Jeans length.The linear analysis would be a good approximation only for density fluctuations of the matter with the density contrast less than 10–5–10–4 at the recombination era. Therefore, a nonlinear analysis which is not based on a perturbation series is required for studying the evolution of the density perturbations, because for this we need a density contrast of 10–2–10–3 at the end of the recombination era.  相似文献   

10.
A sample of 48 observations of coronal mm-wave (off-limb) sources (CMMSs) has been analysed in order to check relationships to cm-wave bursts and to study the emission process. CMMSs appear to be related to gradual and/or stronger microwave bursts with post-burst increase which start up to a few hours prior to the time of the mm-wave observations. The lifetime of CMMSs is much larger than that of these bursts. The interpretation of the mm-wave emission by optically thick bremsstrahlung at the temperature Tb,o ≈ 104 K (which also corresponds to observations in Hα) requires emission measures N2e Δs ≧ 2 · 1028 cm−5 at 37 GHz. On the other hand, optically thin bremsstrahlung at temperatures of Te ≈ 5 · 106–107 K (which are observed in X-rays) can apply to cm-waves. Application of this mechanism to mm-waves, too, would require source sizes much smaller than the half-power beam width (HPBW) of the radio telescopes (so that in this case the presently observed brightness temperatures Tb,o would be underestimated).  相似文献   

11.
On 23 May 1967 energetic (10–50 keV) solar flare X-rays were observed by the OGO-III ion chamber during the period 1808–2100 UT. The time-intensity profile for the X-ray event showed three distinct peaks at 1810, 1841 and 1942 UT. The second peak, which is equivalent to 2.9 × 10–3 ergs cm–2sec–1 above 20 keV, is the largest X-ray burst observed so far by the OGO-I and OGO-III ion chambers. The soft (2–12 Å) X-ray observations reported by Van Allen (1968) also show similar peaks, roughly proportional in magnitude to the energetic X-ray peaks. However, the intensity of energetic X-rays peaked in each case 5–10 min earlier than the soft X-ray intensity indicating a relatively hard photon energy spectrum near the peak of the energetic X-ray emission. The corresponding time-intensity profile for the solar radio emission also showed three peaks in the microwave region nearly coincident with the energetic X-ray peaks. The third radio peak was relatively rich in the metric emission. Beyond this peak both the energetic X-rays and the microwave emission decayed with a time constant of 8 min while the corresponding time constant for the soft X-rays was 43 min. In view of the earlier findings about the energetic X-rays it is indicated that the 23 May solar X-ray event was similar to those observed earlier. During the 23 May event the integral energy flux spectrum at the time of peak intensity is found to be consistent with the form e –E/E 0, E 0 being about 3.4 and 3.7 keV for the peaks at 1841 and 1942 UT, respectively. Assumption of a similar spectrum during the decay phase indicates that the spectral index E 0 decreased nearly exponentially with time.The OGO-III ion chamber, which is also sensitive to protons 12 MeV, observed a solar particle event starting at 2100 UT on 23 May. It could not be determined uniquely which of the two principal X-ray peaks was associated with the particle event, and in fact both may have contributed. The particle intensity reached its maximum value at 1003 UT on 25 May 1967. The equivalent peak radiation dosage was 24 R/hour behind the 0.22 g cm–2 thick aluminum wall of the chamber. This peak radiation dosage was considerably smaller than the maximum dosage (60 R/hour) during the 2 September 1966 solar particle event, the largest event observed so far by the OGO-I and OGO-III satellites. The temporal relationship between the solar X-ray and particle events on 23 May 1967 was similar to that observed in the solar flare events on 7 July 1966, 28 August 1966 and 27 February 1967.  相似文献   

12.
Two bursts of high-energy photons have been discovered during analysis of 2 1/2 years of data from NRL's solar X-ray detector on OSO-6. Both bursts were simultaneously observed by the OGO-5 hard X-ray spectrometer (Kane, 1975). The bursts occurred at about 18 087 s UT on 25 January, 1970, and about 56 532 s UT on 1 October, 1970. The October event was also observed by Vela 5A; however, none of the Vela detectors observed the January event which had an intensity of about 2×10–5 ergs cm–2. Based on these new data, the number of bursts with intensities above about 10–5 ergs cm–2 appears to be about 50% higher than the Vela data alone would indicate.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.  相似文献   

13.
P. Hoyng 《Solar physics》1991,133(1):43-50
The resonant scattering spectrometers of the IRIS ground-based network for measuring whole-disc solar velocity oscillations make use of a piezoelastic modulator. The velocity noise generated by this optical component is analysed with particular emphasis on the required stability of the amplitude of oscillation, a. The product of the absolute stability ¦ a – a m ¦/a m and the relative stability a r.m.s./a m may not be larger than 10 –4 to 10 –5 (depending on specific wishes), where a m is the optimum amplitude. The velocity noise due to photon statistics is slightly enhanced, but other instrumental sources of velocity noise remain unaffected.  相似文献   

14.
X-radiation may result from active plasma phenomena in the interactions of comets with the solar wind. We have carried out a limited but sensitive search for soft X-radiation from Comet Bradfield (1979 ), on 1980 Feb. 5. No X-radiation was detected at a level (3σ) of 1.7 × 10−13 erg(cm2sec keV)−1 in the 0.2 – 4.0 kev range. This corresponds to a limit on the power dissipated in the comet by non-thermal electrons of approximately 1019 ergs sec−1, averaged over the 2568-sec exposure to the comet. This energy deposition is near the magnitude suggested by simple theoretical ideas, and further searches of appropriate comets both in soft X-radiation and at radio wavelengths seem warranted.  相似文献   

15.
Using the data on sunspot groups compiled during 1879&amp;#x2013;1975, we determined variations in the differential rotation coefficientsA andB during the solar cycle. The variation in the equatorial rotation rateA is found to be significant only in the odd numbered cycles, with an amplitude &amp;#x223C; 0.01 &amp;#x03BC; rads-1. There exists a good anticorrelation between the variations of the differential rotation rateB derived from the odd and even numbered cycles, suggesting existence of a &amp;#x2018;22-year&amp;#x2019; periodicity inB. The amplitude of the variation ofB is &amp;#x223C; 0.05 &amp;#x03BC; rad s-1.  相似文献   

16.
Lighthill's method of calculating the aerodynamic emission of sound waves in a homogeneous atmosphere is extended to calculate the acoustic and gravity-wave emission by turbulent motions in a stratified atmosphere. The acoustic power output is P ac 103 o u o 3 /l o M 5 ergs/cm3 sec, and the upward gravity wave flux is F zgr 102 o U o 3 /l o (l o ergs/cm3 sec. Here u 0 is the turbulence velocity scale, l 0 is its length scale, and H the scale height at the atmosphere. M = u 0/c 0 is the Mach number of the turbulence. The acoustic power output is proportional to the maximum value of the turbulence spectrum, and inversely to its rate of falloff at high frequencies. The stratification cuts off the acoustic emission at low Mach numbers. The gravity emission occurs near the critical angle to the vertical c = cos–1 / 2, where 2 2 = ( - 1)/ 2 (c 0/H), and at very short wavelengths. It is proportional to the large wave number tail of the turbulence spectrum. On the sun, gravity-wave emission is much more efficient than acoustic, but can occur only from turbulent motions in stable regions, whereas acoustic waves are produced by turbulence in the convection zone.  相似文献   

17.
Model calculations show that the thermal history of a Moon which originated by fission from the proto-Earth is the same as that for the Moon as it is currently understood. In particular, a fissioned Moon currently has a small percent of partial melt or at least near solidus temperatures below depths of 800 km in accord with the seismic data which show that the deep interior of the Moon has a very lowQ. The models have moderate (20–50%) degrees of partial melting in the upper mantle (depths < 300 or 200 km) in the period between 3 to 4 × 109 years ago and, therefore, can account for the mare filling epoch. Finally the heat flow of the models is 18 ergs cm–2 s–1 which is close to the average of 19 ergs cm–2 s–1 derived from the Apollo heat flow experiments. These findings add further support for the fission origin of the Moon.  相似文献   

18.
Photospheric models were calculated for 90 stars with effective temperatures between 2500 K and 41600 K for five logg-values ranging from 1 to 5. Molecule formation was taken into account. In order to have an idea about possible instabilities in the different stellar layers some quantities, characteristic for convection and turbulence were calculated, such as the Rayleigh-, Reynolds-, Prandtl- and Péclet-numbers. It turned out that all the investigated stars contain unstable layers, including the hottest. Nevertheless, only stars with effective temperatures of 8300 K or less contain layers where the convective energy transport is important. For all stars the convective velocities were calculated and also the generated mechanical fluxes in the convection zones were tabulated.Under the hypothesis that this mechanical energy flux is responsible for the heating of the corona, coronal models were constructed for the Sun and for some stars with effective temperatures between 5000 K and 8320 K for logg-values of 4 or 5.For Main Sequence stars the largest fluxes are generated in F-stars; stars withT eff=7130 K and logg=4 possess also the hottest and most dense coronas with a computed temperature of 3.7·106 K and logN e =10.5.The solar corona computed in this way, on the basis of a photospheric mechanical flux of 0.14·108 erg cm–2 sec–1, has a temperature of 1.3·106 K and logN e =9.8. This density is apparently too high, but even when including in the computations all theoretical refinements proposed in the last few years by various authors it does not appear possible to obtain a solar coronal model with a smaller density.However, when taking into account the inhomogeneous structure of the chromosphere and by associating the calculated mechanical fluxes to the coarse mottles, and lower fluxes to the undisturbed regions we find a mean coronal temperature of 1.1·106 K and a mean logN e -values of 9. The computed velocity of the solar wind at a distance of 104 km above the photosphere has a value between 7 and 11 km sec–1. These latter values are in fair agreement with the observations.  相似文献   

19.
M. Kuperus 《Solar physics》1972,22(2):257-262
The directional dependence of the emission of sound waves in the solar atmosphere is studied. It is shown that quadrupole acoustic radiation generated in convective turbulence is strongly enhanced in the direction of the mean convective flow. The intensity in a direction with the convective velocity is proportional to (1 – M c cos)–17/2, where M c is the Mach number of the convective motion. The influence of the atmospheric cut off frequency on the transmitted acoustic spectrum is taken into account. It is suggested that low frequency atmospheric oscillations may modulate the flux of high frequency sound waves.  相似文献   

20.
Numerical integration of particle trajectories is performed to evaluate the statistical acceleration coefficients D TT for 1 to 100 MeV protons in a solar wind corotating interaction region (CIR) seen at 2.5 and 5.0 AU. Acceleration is followed in the solar wind reference frame and is due to random wave-particle interactions and to random drift motion in moderate scale field gradients. D TT due to the first effect reaches a peak value of 4 × 10 –7 MeV2 s–1 post shock at 10 MeV at 2.5 AU consistent with estimates based both upon cyclotron resonance and transit time damping theory. D TT from the second effect is less well established but is of the order of 10–7 MeV2 s–1 at 10 MeV, 5 AU. A comparison is made between the time constant for statistical acceleration within this CIR and estimates for diffuse shock acceleration and adiabatic deceleration. All three time constants are of the same order, but deceleration is faster than shock acceleration which in turn is faster than statistical acceleration.  相似文献   

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