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1.
G. A. Gurzadyan 《Astrophysics and Space Science》1981,80(1):211-230
It is shown that the observed color diagrams(U-B)
f
(B-V)
f
for pure flare emission of UV Cet type flare stars may be explained within the framework of a fast electron hypothesis. We point out the essential influence on these color indices of the two following factors: (a) the deviations of the normal radiation capability of the star in the infrared region of spectra (on 3.6 m, 4.4 m, and 5.5 m) from the Planckian distribution; (b) the location of the cloud (source) of fast electrons around the star (flare geometry effect). Under the real conditions of the generation of flares around the star the frequency transformation law at the photon-electron interaction has a view =n20, wheren may take the different values-from 0.15 up to 4; it depends on the cloud-star-observer geometry. By the observed colors of the flare emission may be understood, in principle, the location of flare source around the star. A possible role of reflection effect at the generation of stellar flares is outlined. 相似文献
2.
The flare of 12 November 1980, 0250 UT, in Active Region 2779 (NOAA classification) was studied by using X-ray images obtained with the Hard X-Ray Imaging Spectrometer aboard NASA's Solar Maximum Mission. In a ten-minute period, between about 0244 and 0254 UT, some five short-lived impulsive bursts occurred. We found that the so-called hard bursts ( 15 keV) are also detectable in low energy images. During that 10 min period - the impulsive phase - the heat input into the flare and the total number of energetic electrons increased practically exponentially, to reach their maximum values at 0254 UT. At the end of that period, when the thermal energy content of the flare was largest, a burst was observed, for the first time, to spread in a broad southern direction from an initially small area with a speed of about 50 km s–1. We have called this phenomenon a coronal explosion.Fokker Aircraft Industries, Schiphol, The Netherlands. 相似文献
3.
Koujun Yamashita 《Astrophysics and Space Science》1968,2(1):4-22
Rocket-borne photon counters sensitive to bands 1060–1180, 1230–1350, and 1350–1480 were used to measure the celestial ultraviolet radiation above the terrestrial atmosphere. The energy spectra of six objects, Leo, CMa, Ori, , , Ori (combined), Ori, and Tau were obtained. The comparison of them with those calculated with the stellar model atmospheres indicates the deficiency of about 1 mag. in the ultraviolet region, when corrected for interstellar extinction, for all stars except Tau. The observed spectrum of Tau agreed with the theoretical one for normal interstellar extinction. The effects of line blanketing were examined for B1 and B2 stars, and found to account for a part of the difference between the observed and the theoretical values. 相似文献
4.
The flare of 11 November, 1980, 1725 UT occurred in a magnetically complex region. It was preceded by some ten minutes by a gradual flare originating over the magnetic inversion line, close to a small sunspot. This seems to have triggered the main flare (at 70 000 km distance) which originated between a large sunspot and the inversion line. The main flare started at 172320 UT with a slight enhancement of hard X-rays (E > 30 keV) accompanied by the formation of a dark loop between two H bright ribbons. In 3–8 keV X-rays a southward expansion started at the same time, with - 500 km s –1. At the same time a surge-like expansion started. It was observable slightly later in H, with southward velocities of 200 km s–1. The dark H loop dissolved at 1724 UT at which time several impulsive phenomena started such as a complex of hard X-ray bursts localized in a small area. At the end of the impulsive phase at 172540 UT, a coronal explosion occurred directed southward with an initial expansion velocity of 1800 km s–1, decreasing in 40 s to 500 km s–1.Now at Fokker Aircraft Industries, Schiphol, The Netherlands. 相似文献
5.
Correlated optical, radio and X-ray observations are presented for a pair of consequently homologous flares which occurred on March 17, 1970. A rich complexity of behavior in a bright sub-flare with maximum at 1444 UT is repeated in a flare of importance 1B with maximum at 22:49 UT. The unusual and interesting aspect of these flares is that the second flare developed at approximately half the rate of the first. A difference in the trigger mechanism of the two flares is suggested as a possible explanation. 相似文献
6.
We observed the large post-flare loop system, which developed after the X 3.9 flare of 25 June 1992 at 2011 UT, in H with the Multichannel Subtractive Double Pass Spectrograph at Pic-du-Midi and in X-rays with the it Yohkoh/SXT instrument. Following the long-term development of cool and hot plasmas, we have determined the emission measure of the cool plasma and, for the first time, the temporal evolution of the hot-loop emission measure and temperature during the entire gradual phase. Thus, it was possible to infer the temporal variation of electron densities, leading to estimates of cooling times. A gradual decrease of the hot-loop emission measure was observed, from 4 × 1030 cm–5 at 2300 UT on 25 June 1992 to 3 × 1028 cm–5 at 1310 UT on 26 June 1992. During the same period, the temperature decreased only slowly from 7.2 to 6.0 × 106 K. Using recent results of NLTE modeling of prominence-like plasmas, we also derive the emission measure of cool H loops and discuss their temperature and ionisation degree. During two hours of H observations (11–13 hours after the flare) the averaged emission measure does not show any significant change, though the amount of visible cool material decreases and the volume of the loops increases. The emission measure in H, after correction for the Doppler-brightening effect, is slightly lower than in soft X-rays. Since the hot plasma seems to be more spatially extended, we arrive at electron densities in the range n
infe
supho
n
infe
supcool
2 × 1010 cm–3 at the time of the H observations.These results are consistent with the post-flare loop model proposed by Forbes, Malherbe, and Priest (1989). The observed slow decrease of the emission measure could be due to an increase of the volume of the loops and a gradual decrease of the chromospheric ablation driven by the reconnection, which seems to remain effective continuously for more than 16 hours. The cooling time for hot loops to cool down to 104 K and to appear in H would be only a few minutes at the beginning of the gradual phase but could be as long as 2 hours at the end, several hours later. 相似文献
7.
C. D'uston J. M. Bosqued F. Cambou V. V. Temny G. N. Zastenker O. L. Vaisberg E. G. Eroshenko 《Solar physics》1977,51(1):217-229
Solar wind and interplanetary magnetic field data were obtained by the PROGNOZ 1 and PROGNOZ 2 satellites during the period following the August 4, 1972 (0621 UT) solar flare. A thermalized plasma was recorded one hour after the shock followed two hours later by the plasma piston with a bulk velocity higher than 1700 km s-1. The comparison between the PROGNOZ and PIONEER 9 solar wind data shows an attenuation of the plasma properties with the deflection from the flare's meridian. 相似文献
8.
On 21–22 May, 1980 the HXIS instrument aboard SMM imaged an enormous, more-or-less stationary, X-ray arch structure near the position of a large two-ribbon flare which immediately preceded it in time. As described by vestka et al. (1982), the arch remained visible for up to 10 hours. Previous inferences of the height, orientation, and physical parameters of this feature have been based largely on the X-ray data and on radio observations of the associated stationary Type I noise storm. In the present paper we use the observed photospheric line-of-sight magnetic field distribution to compute, in the current-free approximation, the three-dimensional topology of the coronal field above the flare site. Comparing the HXIS intensity contours of the arch to the projected shapes of the field lines suggests that the arch is indeed aligned with certain coronal flux tubes and allows an independent determination of the geometrical arch parameters to be made. This procedure indicates that the true height of the arch is about 70000 km, i.e., appreciably less than was suggested previously (although it is still certainly to be classified as a giant feature of the post-flare evolution).These results suggest that the arch may be a by-product of magnetic reconnection occurring far above the flare site, analogous to the post-flare loops seen at lower heights. Unlike the latter, however, the field lines undergoing reconnection here link more distant parts of the active region; i.e., they do not represent direct linkages across the magnetic neutral line and thus appear to be topologically quite distinct from those which thread the underlying post-flare loops. In fact, of this group of peripheral field lines, the arch could simply comprise the lowest-lying ones to have been opened up by the flare process (and the first to reconnect again). This would explain why both the arch and the post-flare loops were visible early in the decay phase, being products of separate reconnection processes. Moreover, because of the lower plasma density and longer cooling times of the arch, this feature persisted long after the post-flare loops faded from view. A calculation of the magnetic energy liberated by reconnection shows that this process is easily capable of satisfying the overall energy requirements of the arch (the latter as determined from observations).On leave from Los Alamos National Laboratory, Los Alamos, NM 87545, U.S.A. 相似文献
9.
The assumption of a linearly expanding universe for the JBD-cosmological equations generates a set of solutions for the barotropic equations of statep= (=const.). These solutions turn out to be valid for closed space-except in the casep= which is for open space. The gravitational constant which is inversely proportional to the scalar field increases with time if >–1/3 and decreases for <–1/3. No solution exists for =1/3. The Brans-Dicke parameter is negative if <–1/3. 相似文献
10.
We have analysed MgH A
2
-X
2(0.0), (1.1), (2.2), (0.1) and (1.2) absorption bands in a sunspot spectrum. By two different methods, which are almost independent of the estimated value of the correction for stray light, we have determined the solar isotopic ratios of magnesium. These ratios are equal to the terrestrial ones - 24Mg25Mg26Mg = 801010. 相似文献
11.
On May 21/22, 1980 the Hard X-Ray Imaging Spectrometer aboard the SMM imaged an extensive coronal structure after the occurrence of a two-ribbon flare on May 21, 20:50 UT. The structure was observed from 22:20 UT on May 21 until its disappearence at 09:00 UT on May 22.At 22:20 UT the brightest pixel in the arch was located at a projected altitude of 95 000 km above the zero line of the longitudinal magnetic field. At 23:02 UT the maximum of brightness shifted to a neighbouring pixel with approximately the same projected altitude. This sudden shift indicates that the X-ray structure consisted of (at least) two separate arches at approximately the same altitude, one of which succeeded the other as the brightest arch in the structure at 23:02 UT.From 23:02 UT onwards the maximum of brightness did not change its position in the HXIS coarse field of view. With a spatial resolution of 32 this places an upper limit of 1.1 km s-1 on the rise velocity of the arch. Thus, contrary to a similar arch observed on November 6/7, where rise velocities of the order of 10 km s-1 were measured in the same phase of development, the May 22 arch was a stationary structure at an altitude of 145000 km.The following values were estimated for the physically relevant quantities of the May 21/22 arch at the time of its maximum brightness (23:00 UT): temperature T 6.3 × 106 K, electron density n
e
1.1 × 109 cm-3, total emitting volume V 5 × 1029 cm3, energy density 2.9 erg cm–3, total energy contents E 1.4 × 1030 erg, total mass M 9 × 1014 g.The top of the arch was observed at 145 000 km altitude within 1.5 hr after the flare occurrence. Since it seems unlikely that the structure already existed prior to the flare at 20:50 UT, the arch must have risen to its stationary position with an average velocity exceeding 17 km s–1 (possibly much faster). We speculate that the arch was formed very fast at the flare onset, when (part of) the active region loop system was elevated within minutes to the observed altitude. 相似文献
12.
Flaring arches is a name assigned to a particular component of some flares. This component consists of X-ray and H emission which traverses a coronal arch from one to the other of its chromospheric footpoints. The primary footpoint is at the site of a flare. The secondary footpoint, tens of thousands of kilometers distant from the source flare, but in the same active region, brightens in H concurrent with the beginning of the hard X-ray burst at the primary site. From the inferred travel time of the initial exciting agent we deduce that high speed electron streams travelling through the arch must be the source of the initial excitation at the secondary footpoint. Subsequently, a more slowly moving agent gradually enhances the arch first in X-rays and subsequently in H, starting at the primary footpoint and propagating along the arch trajectory. The plasma flow in H shows clearly that material is injected into the arch from the site of the primary footpoint and later on, at least in some events, a part of it is also falling back.Thus a typical flaring arch has three, and perhaps four consecutive phases: (1) An early phase characterized by the onset of hard X-ray burst and brightening of the secondary footpoint in H. (2) The main X-ray phase, during which X-ray emission propagates through the arch. (3) The main H phase, during which H emitting material propagates through the arch. And (4) an aftermath phase when some parts of the ejected material seem to flow in the reverse direction towards the primary site of injection.An extensive series of flaring arches was observed from 6 to 13 November, 1980 at the Big Bear Solar Observatory and with the Hard X-Ray Imaging Spectrometer (HXIS) on board the SMM in a magnetically complex active region. The two most intense arches for which complete H and X-ray data are available and which occurred on 6 November at 17 21 UT (length 57000 km) and on 12 November at 16 57 UT (length 263 000 km) are discussed in this paper. 相似文献
13.
Z. Švestka B. R. Dennis M. Pick A. Raoult C. G. Rapley R. T. Stewart B. E. Woodgate 《Solar physics》1982,80(1):143-159
For almost 30 hr after the major (gamma-ray) two-ribbon flare on 6 November 1980, 03:30 UT, the Hard X-Ray Imaging Spectrometer (HXIS) aboard the SMM satellite imaged in > 3.5 keV X-rays a gigantic arch extending above the active region over the limb. Like a similar configuration on 22 May 1980, this arch formed the lowest part of a stationary post-flare radio noise storm recorded at metric wavelengths at Nançay and Culgoora. 6.5 hr after the flare a coronal region below the arch started quasi-periodic pulsations in X-ray brightness, observed by several SMM instruments. These brightness variations had no response in the chromosphere (H), very little in the transition layer (O v), but they clearly correlated with similar variations in brightness at 169 MHz. There were 13 pulses of this kind, with apparent periodicity of about 20 min, until another flare occurred in the active region at 15:00 UT. All the brightenings appeared within a localized area of about 30000 km2 in the northern part of the active region, but they definitely did not occur all at the same place.The top of the X-ray arch, at an altitude of 155 000 km, was continuously and smoothly decaying, taking no part in the striking variations below it. Therefore, the area variable in brightness does not seem to be the footpoint of the arch, as we supposed for similar variations on 22 May. More likely, it is a separate region connected directly with the source of the radio storm; particles accelerated in the storm may be dumped into the low corona and cause the X-ray enhancements. The X-ray arch was enhanced by two orders of magnitude in 3.5–5.5 keV X-ray counts and the temperature increased from 7.3 × 106 to 9 × 106 K when the new two-ribbon flare occurred at 15:00 UT. Thus, it is possible that energy is brought into the arch via the upper parts of the reconnecting flare loops - a process that can continue for hours. 相似文献
14.
We have analyzed the H filtergrams and vector magnetograms of the active region NOAA 7070, in which a 3B/X3.3 flare occurred on February 27, 1992. The average area per sunspot of this active region was in declining phase at the time of the flare. The vector magnetograms indicate that the magnetic field was non-potential at the flaring site. Besides non-potentiality, the longitudinal field gradient was found to be the highest at the region showing initial H brightening. Further, in H filtergrams no appreciable change in the morphology of the filament tracing the magnetic neutral line was noticed in the post-flare stage. Also, the photospheric vector magnetograms show considerable shear in post-flare magnetic field of the active region. In this paper we present the observations and discuss the possible mechanism responsible for the 3B/X3.3 flare. 相似文献
15.
, 1-, 2- 3- . , . 相似文献
16.
A limiting case of the problem of three bodies (m
0,m
1,m
2) is considered. The distance between the bodiesm
0 andm
1 is assumed to be much less than that between their barycenter and the bodym
2 so that one may use Hill's approximation for the potential of interaction between the bodiesm
1 andm
2. In the absence of resonant relations the potential, double-averaged by the mean longitudes ofm
1 andm
2, describes the secular evolution of the orbits in the first approximation of the perturbation theory.As Harrington has shown, this problem is integrable. In the present paper a qualitative investigation of the evolution of the orbits and comparison with the analogous case in the restricted problem are carried out.The set of initial data is found, for which a collision between the bodiesm
0 andm
1 takes place.The region of the parameters of the problem is determined, for which plane retrograde motion is unstable.In a special example the results of approximate analysis are compared with those of numerical integration of the exact equations of the three body problem.
m 0,m 1,m 2. , m 0 m 1. m 2, m 1 m 2 m 1 m 2 . , . . , m 0 m 1. , . .相似文献
17.
18.
-- () ., , , , , . , , . , . 相似文献
19.
20.
A time series of K3 spectroheliograms taken at the Coimbra Observatory exhibits an erupting loop on the east limb on July 9, 1982 in active region NOAA 3804. The Goddard SMM Hard X-Ray Burst Spectrometer (HXRBS) observations taken during this period reveal a hard X-ray flare occurring just before the loop eruption is observed, and SMS-GOES soft X-ray observations reveal a strong long-duration event (LDE) following the impulsive phase of the flare. A Solwind coronagram exhibits a powerful coronal mass ejection (CME) associated with the erupting loop. H flare and prominence observations as well as centimeter and decimeter radio observations of the event are also reviewed. A large, north–south-oriented quiescent prominence reported within the upper part of the CME expansion region may play a role in the eruption as well. The spatial and temporal correlations among these observations are examined in the light of two different current models for prominence eruption and CME activation: (1) The CME is triggered by the observed hard X-ray impulsive flare. (2) The CME is not triggered by a flare, and the observed soft X-ray flare is an LDE due to reconnection within the CME bubble. It is concluded that this event is probably of a mixed type that combines characteristics of models (1) and (2). The July 9 event is then compared to three other energetic CME and flare eruptions associated with the same active-region complex, all occurring in the period July 9 through September 4, 1982. It is noted that these four energetic events coincide with the final evolutionary phase of a long-lasting active-region complex, which is discussed in a companion paper (Bumba, Garcia, and Jordan, 1997). The paper concludes by addressing the solar flare myth controversy in the light of this work. 相似文献