共查询到20条相似文献，搜索用时 31 毫秒
1.
High-speed jets of solar quiet regions have been observed at Big Bear Solar Observatory in H–1.0 Ú, and compared with high-resolution magnetograms. Over the whole Sun, the birthrate of the H–1.0 Ú jets is about 19±3 events s–1, which is much lower than the birthrate of spicules. The average lifetime of these jets is 2±1 min. H–1.0 Ú jets are very different from spicules, in the sense of birthrate, lifetime, and shape. Jets tend to recur in the same sites, always located in boundaries of supergranules. Under the best observing conditions, we found that 80% of the major jet sites are associated with converging magnetic dipoles – mainly the sites where intranetwork elements are canceling with opposite polarity network elements. In order to establish a possible relationship between the disk H jets and limb macrospicules, we have also obtained time sequences of H center-line images at the limb. These images are enhanced by median filtering so that jet structures over the limb are easily studied. We found that these limb H jets (above the spicule forest) repeatedly occur in the same sites, which is the property shared by the disk H–1.0 Ú jets. However, their mean lifetime is 10 min, substantially longer than that of disk jets. Comparison with simultaneous SOHO/EIT Heii 304 Ú images shows that every Heii 304 Ú jet over the limb coincides with an H jet, although Heii 304 Ú jets extend much farther out. Some H jets do not have associated He jets, probably due to the difference in image resolutions. H spectra of selected jets are analyzed, and we found that jets are not simply blue-shifted; instead, the line profiles are broadened with significantly larger broadening on the blue side. Two-component fitting finds that the velocity of the blue-shifted component (an optically-thin component) is around 20 to 40 km s–1. 相似文献
2.
The eruptive prominence observed on 27 May 1999 in H at Ondejov Observatory is analyzed using image-processing techniques. To understand the physical processes behind the prominence eruption, heated structures inside the cold H prominence material are sought. Two local minima of intensity (holes), the first above and the second below the erupting H prominence, have been found in the processed H images. A comparison of H images with the SOHO/EIT and Yohkoh/SXT images showed: (a) the cold H prominence is visible as a dark feature in the EIT images, (b) the upper local minimum of intensity in the H image corresponds to a hot structure seen in EIT, (c) the lower minimum corresponds to a hot loop observed by SXT. The physical significance of the H intensity minima and their relation to the hot structures observed by EIT and SXT is discussed. The time sequence of observed processes is in favor of the prominence eruption model with the destabilization of the loop spanning the prominence. For comparison with other events the velocities of selected parts of the eruptive prominence are determined. 相似文献
3.
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
4.
We analyzed simultaneous EUV images from the Transition Region And Coronal Explorer (TRACE) and H and H filtergrams from Huairou Solar Observing Station (HSOS). In active region NOAA 8307, an H C5.5 flare occurred near 06:10 UT on 23 August 1998. In this paper, we concentrated on loop–loop interaction, as well as their relationship to the C5.5 flare. We find that while opposite polarity magnetic fields cancelled each other, H bright points appeared, and then the flare occurred. Looking at EUV images, we noticed that a TRACE flare, associated with the C5.5 flare in H and H filtergrams, first appeared as patch-shaped structures, then the flare patches expanded to form bright loops. We used a new numerical technique to extrapolate the chromospheric and coronal magnetic field. Magnetic field loops, which linked flare ribbons, were found. It was suggested that loop interaction in the active region was the cause of the TRACE and H flare; the magnetic topological structures were clearly demonstrated and the TRACE flare was probably due to the interaction among energetic low-lying and other longer (higher) magnetic loops. Each primary flare kernel, seen from H, H filtergrams, and EUV images, was located near the footpoints of several interacting loops. 相似文献
5.
P. R. Wilson 《Solar physics》1981,69(1):9-14
Simultaneous observations of fine structure photospheric features at several wavelengths are described. The observations, which include regions near disk center and at the limb, were obtained using a narrow band calcium filter and selected wavelengths in Mg b1, the red wing of H and the H continuum using the Universal Birefringent Filter of the Sacramento Peak Observatory.From the disk-center series it is concluded that bright point structures seen in calcium are cospatial with the H filigree and are related in origin.The limb photographs confirm that the calcium network is cospatial with the white light faculae. However, in regions of good seeing it is clear that even at the limb the calcium network patterns consist of individual bright points which are essentially the same as those seen near disk center.Thus it is concluded that the white light faculae, the H filigree and the calcium bright points are different manifestations of the same photospheric features.On leave from Department of Applied Mathematics, University of Sydney, Australia.The Sacramento Peak Observatory is operated by the Association of Universities for Research in Astronomy, Inc. under contract AST 78-17292 with the National Science Foundation. 相似文献
6.
We report on a prominence eruption as seen in H with the Crimean Lyot coronagraph, the global H network, and coronal images from the LASCO C2 instrument on board SOHO. We observed an H eruption at the northwest solar limb between 07:38:50 UT and 07:58:29 UT on 11 August 2000. The eruption originated in a quiet-Sun region and was not associated with an H filament. No flare was associated with the eruption, which may indicate that, in this case, a flux rope was formed prior to the eruption of the magnetic field. The H images and an H Dopplergram show a helical structure present in the erupted magnetic field. We suggest that the driving mechanism of the eruption may be magnetic flux emergence or magnetic flux injection. The limb H observations provide missing data on CME speed and acceleration in the lower corona. Our data show that the prominence accelerated impulsively at 5.5 km s–2 and reached a speed slightly greater than 800 km s–1 in a narrow region (h<0.14 R
) above the solar surface. The observations presented here also imply that, based only on a CME's speed and acceleration, it cannot be determined whether a CME is the result of a flare or an eruptive prominence. 相似文献
7.
M. Dizer 《Solar physics》1969,10(2):416-428
We report measurements made on the brightness in H of all parts of the flare photographed through a birefringent filter centered on H, using a scanning isodensitometer. From obtained isophotes of the flares we derived some information on the morphological changes in the flare and estimated the total energy in H of the flare. 相似文献
8.
Edward N. Frazier 《Solar physics》1972,24(1):98-112
High resolution photographic magnetograms are compared with H filtergrams (both on- and off - band) for a wide variety of solar features. It is verified that H filaments overlie neutral lines or bands and that H plages always occur at magnetic field clumps. However, the brightness of H plages bear no relation to magnetic field strength or polarity, and the direction of the magnetic field with respect to threads and filaments remains obscure. Counter-examples can be found for virtually every rule that has been formulated so far.Basic questions about the usefulness and final research goal of filtergrams and magnetograms are raised. It is shown that neither filtergram or magnetogram alone is capable of furnishing a unique solution. It is suggested that the proper direction for research is to use magnetograms, together with (as yet unspecified) additional sources of data, to understand H structures. 相似文献
9.
The Big Bear Solar Observatory (BBSO) has a long tradition of synoptic full-disk observations. Synoptic observations of contrast enhanced full-disk images in the Caii K-line have been used with great success to reproduce the Hi L irradiance variability observed with the Upper Atmosphere Research Satellite (UARS). Recent improvements in data calibration procedures and image- processing techniques enable us now to provide contrast enhanced H full-disk images with a spatial resolution of approximately 2 and a temporal resolution of up to 3 frames min–1.In this first paper in a series, we describe the instruments, the data calibration procedures, and the image-processing techniques used to obtain our daily H full-disk observations. We also present the final data products such as low- and high-contrast images, and Carrington rotation charts. A time series of an erupting mini- filament further illustrates the quality of our H full-disk observations and motivate one of the future research projects. This lays a solid foundation for our subsequent studies of solar activity and chromospheric fine structures. The high quality and the sunrise- to-sunset operation of the H full-disk observations presented in this paper make them an ideal choice to study statistical properties of mini-filament eruptions, chromospheric differential rotation, and meridional flows within the chromosphere, as well as the evolution of active regions, filaments, flares, and prominences. 相似文献
10.
We analyze a time series of high resolution observations near the solar limb, obtained in H and the Mg b1 line. We identified arch-shaped dark mottles, which are thin, faint H structures observable under very good seeing conditions, best seen in H +0.75 Å. Their mean length is about 15, their mean height about 6 and indicative lifetimes is of the order of 5 min. They show negative (away from the observer) line-of-sight velocities. A possible interpretation is that material flows from the apex towards the feet of the arches. 相似文献
11.
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
12.
Marie K. McCabe 《Solar physics》1973,30(2):439-448
There are remarkable similarities in the structure of loop prominences when observed in H and coronal lines, although the lines arise from extremely different excitation conditions. This leads to the consideration of a multi-component model, where different emission lines come from different elements of the structure. The late phases of a large west limb loop prominence system followed by a surge were recorded at Haleakala Observatory on March 6, 1970. Simultaneous filter-grams in H and 5303 were obtained, together with spectra at three heights in the prominence over the range 3850–5950 Å. The positions of bright knots of emission as seen in the green line are compared with associated H knots. With these relative positions determined, the filtergrams are superimposed to demonstrate the two dimensional spatial relationship between H and 5303 structures. The results support a model of cool loops within a closely associated hot loop system. 相似文献
13.
Based on the photospheric vector magnetograms taken at Huairou Solar Observing Station (HSOS), H images taken at Hiraiso Solar Terrestrial Research Center of Communication Research Laboratory, soft X-ray images taken by Yohkoh and an extrapolation method, the magnetic field structures and some active phenomena of the active region AR 7321 around 04:12 UT on 27 October 1992 are analyzed in this paper. A divergence of the transverse magnetic field, located at a newly formed spot, was found. At least four highly sheared magnetic field systems separately spread from this divergence to four other sites around this divergence. Vertical current concentrations are upward in this region and downward in the other four sites, and the corresponding H bright patches and soft X-ray bright loops coincide with these structures, confirming the existence of these four systems. The extrapolated magnetic force lines reconstructed by the Boundary Element Method (BEM), force-free field assumption, and boundary condition of observed photospheric vector magnetic field, coincide in space with the H bright patches and soft X-ray bright loops, showing that this extrapolation method is very effective and suggesting that the H bright patches and soft X-ray bright loops in this case represent the magnetic field structures in the upper atmosphere of the Sun.The bright structures in the H images and the soft X-ray images have a close correlation with the non-potential characteristics of the magnetic fields. 相似文献
14.
M. R. Kundu 《Solar physics》1972,25(1):108-115
At 3.5 mm wavelength absorption features are observed in correspondence with H dark filaments on the disk; beyond the limb the prominences correspond to emissive regions. The absorption features are larger (2–3 arc) than the corresponding H dark filaments; the emissive regions at the limb have similar angular sizes. The emissive regions at the limb have electron temperatures of 5500±500 K; the amount of absorption observed on the disk leads to mean electron densities of about 5 × 1010 per cm3. 相似文献
15.
We obtained a complete set of H, Ca 8542 and He I 10830 spectra and slit-jaw H images of the C5.6 limb flare of 1 August 2003 using the Multi-channel Infrared Solar Spectrograph (MISS) at Purple Mountain Observatory. This flare was also observed by the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and partially by the Extreme-ultraviolet Imaging Telescope (EIT) on SOHO. This flare underwent a rapid rising and expanding episode in the impulsive phase. All the H, Ca 8542 and He I 10830 profiles of the flare are rather wide and the widest profiles were observed in the middle bright part of the flare instead of at the flare loop top near the flare maximum. The flare manifested obvious rotation in the flare loop and the decrease of the rotation angular speed with time at the loop-top may imply a de-twisting process of the magnetic field. The significant increases of the Doppler widths of these lines in the impulsive phase reflect quick heating of the chromosphere, and rapid rising and expanding of the flare loop. The RHESSI observations give a thermal energy spectrum for this flare, and two thermal sources and no non-thermal source are found in the reconstructed RHESSI images. This presumably indicates that the energy transfer in this flare is mainly by heat conduction. The stronger thermal source is located near the solar limb with its position unchanged in the flare process and spatially coincident with the intense EUV and H emissions. The weaker one moved during the flare process and is located in the H dark cavities. This flare may support the theory of the magnetic reconnections in the lower solar atmosphere. 相似文献
16.
Oddbjörn Engvold 《Solar physics》1969,8(2):284-290
The relative position of sunspots as observed in the core of H and in the continuum has been studied in 316 spectra of 84 different sunspots. We find that chromospheric features surrounding sunspots may produce apparent shifts of the spots in the core and in the wing of H. In addition a shift directed towards the limb is found. This shift is found to be a height effect. The difference in height between the levels of the H core and the continuum varies from 2300 km to 1000 km for different sunspots. 相似文献
17.
One hundred seventy-eight Ellerman bombs were identified and studied with on- and off-band H filtergrams of two active centers, one near disk center and the other near the east limb. The photographs, taken through a 1/4 Å bandpass filter, occasionally attained resolution as fine as 0.3. The mean duration of bombs at H-2 Å was about 13 min near disk center and 11 min near the limb; these times increase slightly when we observe closer to the core of H. Eighty-six percent of the bombs in the near-limb region and 56% in the disk-center region were seen to be accompanied by ejections of dark material; the ejections were 3–30 long. The ejection length appears to be proportional to the bomb size times the bomb lifetime. 相似文献
18.
In this paper we present a detailed study of a violent evolution of the 18 September 1995 eruptive prominence observed by the H telescope and the Multichannel Optical Flare Spectrograph in Ondejov. The fast changes of the prominence structure started immediately after a weak radio burst at 3 GHz. This circumstance shows the presence of non-thermal processes. In the later phase of the prominence evolution a comparison of the H filtergrams with the Yohkoh Soft X-ray Telescope pictures was made. For a search of fine structures in the H images, an image processing technique was used. A detailed analysis of observations indicates magnetic field line reconnection, mainly in space below the rising H prominence. These reconnection processes are manifested not only by structural changes of the H prominence and X-ray loops but also by the character of Doppler velocities. Evidence of splitting and rotation was found in the H spectrum formed close to the reconnection space, and the typical velocities of such plasma movement were evaluated. We estimated amplitudes of rotational velocities, giving evidence about the rearrangement of helical structures during the process of the eruptive prominence activation. In the conclusion we discuss some implications of our results. 相似文献
19.
Sudden brightening of FeII and Balmer (H and H) lines of X Oph was observed on 28–29 May, 1986. Equivalent width of FeII and H lines increased by a factor of two and that for H line by a factor of four, during the brigtening phase of the star. This brightening phenomena has been explained in the framework of Coronal Radiative Instability. 相似文献
20.
High resolution single dish observations of the solar radio emission with the Effelsberg 100-m telescope at 8.5 mm wavelength (antenna beam width is 31) show a good correlation of small active regions, seen in quiet Sun areas, associated with the longitudinal magnetic fields, but not with structures seen in H light.Some characteristics of these 8.5 mm structures, such as diameter and temperature, point to a correlation with supergranular cells. Although the lifetime of these structures is longer than several hours, weak intensity variations within a time scale of minutes could be recorded. From the observational results it was possible to derive roughly an energy dissipation rate for the 8.5 mm structures. This value is a factor of 100 higher than that obtained earlier at 2.8 cm wavelength in a similar manner.A center-to-limb variation at 8.5 mm, especially a limb brightening, could not be detected. 相似文献