共查询到20条相似文献，搜索用时 31 毫秒
1.
A synthesis of the centimetric and millimetric observations of the prominences on the disk is performed using the published radio maps as well as original observations. It is shown that the size of the radio depressions associated with large quiescent H filaments is similar to the H size. A spectrum of the brightness temperature of the radio filaments between 3.5 mm and 6 cm- is derived. 相似文献
2.
We present high resolution detailed observations of the class 3N two-ribbon flare of 1973, July 29 (McMath 12461), which was associated with the disappearance of a large filament (disparition brusque). This flare occurred in a diffuse bipolar magnetic region completely devoid of sunspots, and was further associated with a type IV radio burst and a soft X-ray event. Extensive H filtergraph, spectrograph and magnetograph records during the main phase of the flare suggest that downfalling and streaming material is present on both ribbons for several hours during the H emission enhancement, but only at a small number of points located both on and off the ribbons. We find a poor spatial correspondence between bright emission knots in the H ribbons and the positions of the observed downward motion. We conclude that the model of infall-impact of Hyder (1967a, b) is not consistent with our filtergraph and spectrograph observations.Presently at the University of Michigan, Ann Arbor, Michigan. 相似文献
3.
A flare event occurred which involved the disappearance of a filament near central meridian on 29 August 1973. The event was well observed in X-rays with the AS & E telescope on Skylab and in H at BBSO. It was a four-ribbon flare involving both new and old magnetic inversion lines which were roughly parallel. The H, X-ray, and magnetic field data are used to deduce the magnetic polarities of the H brightenings at the footpoints of the brightest X-ray loops. These magnetic structures and the preflare history of the region are then used to argue that the event involved a reconnection of magnetic field lines rather than a brightening in place of pre-existing loops. The simultaneity of the H brightening onsets in the four ribbons and the apparent lack of an eruption of the filament are consistent with this interpretation. These observations are compared to other studies of filament disappearances. The preflare structures and the alignment of the early X-ray flare loops with the H filament are consistent with the schematic picture of a filament presented first by Canfield et al. (1974). 相似文献
4.
The characteristics of 3.5 mm depression features associated with two disparition brusques observed in H are discussed. The millimeter depressions still exist, although reduced in strength, after the disappearance of the H filament. The two depressions correspond to temperatures of 600 and 450 K before and to 200 and 250 K after the H filament disappearance. 相似文献
5.
Quasi simultaneous H and radio observations of LSI+61o303 during August-September 1993 are presented. The radio data show that during the studied epoch the outburst has peaked at radio phase 0.6, at level100 mJy. No significant variations in the H profile at phases 0.5 to 0.65 have been detected. A remarkable increase of the EW and FWHM of the H blue peak is observed at radio phase 0.23. Possible reasons are considered. 相似文献
6.
Yoshihisa Irimajiri Toshiaki Takano Hiroshi Nakajima Kiyoto Shibasaki Yoichiro Hanaoka Kiyoshi Ichimoto 《Solar physics》1995,156(2):363-375
Radio images and spectra of an eruptive prominence were obtained from simultaneous multifrequency observations at 36 GHz, 89 GHz, and 110 GHz on May 28, 1991 with the 45-m radio telescope at Nobeyama Radio Observatory (NRO), the National Astronomical Observatory, Japan (NAOJ). The radio spectra indicated that the optical depth is rather thick at 36 GHz whereas it is thin at 89 and 110 GHz. The H data, taken at Norikura Solar Observatory, NAOJ, suggest that the eruption of an active region filament was triggered by an H flare. The shape and position of the radio prominence generally coincided with those of H images. The radio emission is explained with an isothermal cool thread model. A lower limit for the electron temperature of the cool threads is estimated to be 6100 K. The range of the surface filling factors of the cool threads is 0.3–1.0 after the H flare, and 0.2–0.5 in the descending phase of the eruptive prominence. The column emission measure and the electron number density are estimated to be of the order of 1028 cm–5 and 1010 cm–3, respectively. The physical parameters of a quiescent prominence are also estimated from the observations. The filling factors of the eruptive prominence are smaller than those of the quiescent prominence, whereas the emission measures and the electron densities are similar. These facts imply that each cool thread of the prominence did not expand after the eruption, while the total volume of the prominence increased. 相似文献
7.
This investigation shows that statistically there are significant time delays between H and hard X-ray (HXR) emissions during solar flares; most impulsive flares produce HXR emissions up to 1 min before and up to 2 min after the onset of H emission. HXR emissions are also found to be peaked up to 2 min before the H emissions. 相似文献
8.
Anton Bruzek 《Solar physics》1972,26(1):94-107
The results of new observations of moustaches in H filtergrams and in H spectra are presented and their relations to photospheric and chromospheric phenomena are studied. The main findings and conclusions are: (1) previous results on basic data (size, brightness, lifetime, etc.) are essentially confirmed; (2) limb observations located the moustaches at the base of the structured H chromosphere, just above the level of the emission of H±1 Å. At the disk moustaches are, in general, covered by absorbing and slightly Doppler-shifted chromospheric elements which determine the H core in the moustache spectrum. However, absorption-free moustaches with an H emission core revealing a pure (true) moustache spectrum have also been found; (3) moustaches have been found to coincide with continuous facular granules; it is suggested that they are an extension of facular granules into the chromosphere rather than a low-level flare-like phenomenon.Mitteilung aus dem Fraunhofer Institut, No. 114. 相似文献
9.
The location of H filaments is compared with maps of the photospheric line of sight velocity V
and the magnetic field H
. It is found that (1) H filaments are associated with regions of ¦V
¦ 300m s–1, (2) always both positive as well as negative velocities are present under H structures, (3) stable (long lasting) portion of filaments frequently occur at the position of H
= 0 as well as V
= 0 lines, (4) this association remains valid for the longitudes less than 50° from central meridian. 相似文献
10.
We have observed an H dark filament at 8, 15, and 22 GHz and derived the radio spectrum of the filament. We suggest that the filament has to be optically thick at radio frequencies and that the observed spectrum is due to the presence of a transition sheath surrounding the filament. We examine a model for the transition sheath in which the energy radiated away is balanced by the conduction of heat from the corona, and show that the radio observations indicate that little or no thermal energy is conducted into the main body of the filament. We compare the model with ultraviolet observations of filaments and discuss how the discrepancies can be removed.On leave of absence from Tata Institute of Fundamental Research, Bombay, India. 相似文献
11.
A. Bruzek 《Solar physics》1972,24(1):118-122
The relation between occurrence of H loops and filaments is discussed on the occasion of the observation of a new type of transient loops during a flare associated filament activation. Considering all known types of loop systems crossing neutral lines it is concluded that concurrent existence of stable filaments and H loops is incompatible.Mitt. aus dem Fraunhofer Institut No. 112. 相似文献
12.
The H observations of a selected sample of bright Be stars are presented. The available infrared observations at K band (2.2 m) of these stars have been used to find the infrared excess emission. The analysis of the combined data show thatL
H, the luminosity of the H emission line, is proportional toL
IR, the luminosity of the infrared excess emission. The linear correlation betweenL
IR andL
H shows that both the infrared excess and the H line originate in a common region. It is also detected that the infrared excess emission is produced throughout the whole envelope whereas the H is emitted in some defined region of the circumstellar (CS) envelope. 相似文献
13.
127 hr of high-resolution H movies of young active regions have been compared with simultaneous 1.5–15 keV X-ray measurements from the Mapping X-Ray Heliometer experiment on OSO-8, with particular attention to preflare periods and to the possibility of X-ray emission associated with filament activity during that time. The period studied included 8 confirmed flares or subflares, 16 unreported events of comparable magnitude, and numerous examples of filament activity. We found no evidence for X-ray emission from areas of enhanced filament activity unless simultaneous brightenings were present in H. In addition, we detected no peculiar behavior of either filaments or X-rays during the period of approximately 20 min preceding these small flares which, even in retrospect, would have allowed them to be predicted. 相似文献
14.
The impulsive phase of a large solar limb flare of June 20, 1989 总被引：1，自引：0，他引：1
On 1989 June 20, we observed in H the impulsive phase of a 3B/X1.6 limb flare with high temporal resolution. Line profiles have been acquired every 2.3 s with an imaging spectrograph. During the eruption of a filament we observed in H a moving plasma blob from what we believe to be a second loop which correlated spatially and temporally with a microwave source at 1.4 GHz observed by VLA. A magnetodynamic model is used to understand the development of the moving plasma blob. 相似文献
15.
We present the observation and interpretation of a solar radio burst whose evolution of the source position at 48 GHz has been correlated with microwave spectral observations from 3.1 to 19.6 GHz and H imaging spectrograms. The event of November 19, 1990 showed 4 impulsive peaks in microwaves and 2 H kernels. There exists strong evidence that the impulsive emission has originated from nonthermal electrons including an electron beam during the rising phase of the third microwave peak. The complex evolution of the source position at 48 GHz is attributed to two inhomogeneous and spatially separated sources with changing relative brightness. 相似文献
16.
We have compared the structures seen on X-ray images obtained by a flight of the NIXT sounding rocket payload on July 11, 1991 with near-simultaneous photospheric and chromospheric structures and magnetic fields observed at Big Bear. The X-ray images reflect emission of both Mgx and Fexvi, formed at 1 × 106 K and 3 × 106 K, respectively. The brightest H sources correspond to a dying sub-flare and other active region components, all of which reveal coronal enhancements situated spatially well above the H emission. The largest set of X-ray arches connected plages of opposite polarity in a large bipolar active region. The arches appear to lie in a small range of angle in the meridian plane connecting their footpoints. Sunspots are dark on the surface and in the corona. For the first time we see an emerging flux region in X-rays and find the emission extends twice as high as the H arches. Many features which we believe to correspond to X-ray bright points (XBPs) were observed. Whether by resolution or spectral band, the number detected greatly exceeds that from previous work. All of the brighter XBPs correspond to bipolar H features, while unipolar H bright points are the base of more diffuse comet-like coronal arches, generally vertical. These diverge from individual features by less than 30°, and give a good measure of what the canopies must do. The H data shows that all the H features were present the entire day, so they are not clearly disappearing or reappearing. We find a new class of XBPs which we call satellite points, elements of opposite polarity linked to nearby umbrae by invisible field lines. The satellite points change rapidly in X-ray brightness during the flight. An M1.9 flare occurred four hours after the flight; examination of the pre-flare structures reveals nothing unusual. 相似文献
17.
R. T. Stewart 《Solar physics》1984,94(2):379-385
A study of type II solar radio bursts recorded at 160 MHz by the Culgoora radioheliograph during 1980 to 1982 shows that the radio emission occurs above H filaments rather than above H flares. This suggests that the type II radio emission most probably originates from within a coronal helmet streamer overlying the filament channel. 相似文献
18.
T. B. H. Kuiper 《Solar physics》1973,33(2):461-474
Isolated type III radio burst activity was observed at Clark Lake Radio Observatory in March and the first part of April, 1971, to occur in discrete regions of the corona above certain active regions. When these regions were examined under high resolution in H all the type III events appeared to have associated activity in H. The potential coronal magnetic field in these regions appeared to be either open or diverging, whereas the field over a rather active region which did not have radio burst activity was closed in a magnetic arcade. The latter feature has been associated with streamers. Streamers have also been associated with dark filaments. The occurrence of a stable dark filament in an active region appeared to have an inhibiting effect on type III activity. It is suggested that a streamer field configuration is not favorable to the escape of isolated type III exciters. 相似文献
19.
One-hundred fifty-six large-scale enhancements of X-ray emission from solar active regions were studied on full-disk filterheliograms to determine characteristic morphology and expansion rates for heated coronal plasma. The X-ray photographs were compared with H observations of flares, sudden filament disappearances, sprays and loop prominence systems (LPS). Eighty-one percent of the X-ray events were correlated with H filament activity, but only forty-four percent were correlated with reported H flares. The X-ray enhancements took the form of loops or arcades of loops ranging in length from 60 000 km to 520 000 km and averaging 15 000 km in width. Lifetimes ranged from 3 hr to >24 hr. Event frequency was 1.4 per day. X-ray loop arcades evolved from sharp-edged clouds in cavities vacated by rising H filaments. Expansion velocities of the loops were 50 km s-1 immediately after excitation and 1–10 km s-1 several hours later. These long-lived loop arcades are identified with LPS, and it is suggested that the loops outlined magnetic fields which were reconnecting after filament eruptions. Another class of X-ray enhanced loops stretched outside active regions and accompanied sprays or lateral filament ejections. H brightenings occurred where these loops intersected the chromosphere. Inferred excitation velocities along the loops ranged between 300 and 1200 km s-1. It is suggested that these loops outlined closed magnetic fields guiding slow mode shocks from flares and filament eruptions. 相似文献
20.
Sara F. Martin 《Solar physics》1979,64(1):165-176
Bright and dark curvilinear structures observed between the two major chromospheric ribbons during the flare of 29 July 1973 on films from the Big Bear Solar Observatory are interpreted as a typical system of coronal loops joining the inner boundaries of the separating flare ribbons. These observations, made through a 0.25 Å H filter, only show small segments of the loops having Doppler shifts within approximately ± 22 km s–1 relative to the filter passband centered at H, H -0.5 Å or H +0.5 Å. However, from our knowledge of the typical behavior of such loop systems observed at the limb in H and at 5303 Å, it has been possible to reconstruct an appoximate model of the probable development of the loops of the 29 July flare as they would have been viewed at the limb relative to the position of a prominence which began to erupt a few minutes before the start of the flare. It is seen that the loops ascended through the space previously occupied by the filament. On the assumption that H fine structures parallel the magnetic field, we can conclude that a dramatic reorientation of the direction of the magnetic field in the corona occurred early in the flare, subsequent to the start of the eruption of the filament and prior to the time that the H loops ascended through the space previously occupied by the filament. 相似文献