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Simultaneous measurements of magnetic fields and brightness fields using a 4-image spectroheliograph
The use of an auxiliary beamsplitter with the Kitt Peak 15-foot spectroheliograph permits spectroheliograms to be taken simultaneously in 4 identical images of the sun. By using two of these images for a Zeeman spectroheliogram, a third image for a Fei 4071 spectroheliogram, and the fourth image for a 6107Å continuum spectroheliogram, simultaneous measurements of magnetic fields and brightness fields have been obtained. Within the limits of intensity variations imposed by doppler shifts and brightness fluctuations of the continuum, a quantitative relation does exist between the measured values of brightness and magnetic field strength of the photospheric network. For intensities measured +0.12 Å from the core of Fei 4071, this relation is ln(1 +I/I) = ¦B
¦, whereB
refers to the component of magnetic field normal to the solar surface,I/I is the fractional excess of brightness of the magnetic regions relative to the brightness of non-magnetic regions, and = (6±2)%/100 gauss.Kitt Peak National Observatory Contribution No. 538.Operated by The Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.Visiting Astronomer, Solar Division, Kitt Peak National Observatory. 相似文献
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The nature of thin, highly inclined threads observed in quiescent prominences has puzzled solar physicists for a long time. When assuming that the threads represent truly inclined magnetic fields, the supporting mechanism of prominence plasma against gravity has remained an open issue. This paper examines the levitation of prominence plasma exerted by weakly damped MHD waves in nearly vertical magnetic flux tubes. It is shown that the wave damping, and resulting `radiation pressure', caused predominantly by ion-neutral collisions in the `cold' prominence plasma, may balance the acceleration of gravity provided the oscillation frequency is 2 rad s–1 (f0.5 Hz). Such short wave periods may be the result of small-scale magnetic reconnections in the highly fragmentary magnetic field of quiescent prominences. In the proposed model, the wave induced levitation acts predominantly on plasma – neutral gas mixtures. 相似文献
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An eruptive prominence of June 10, 1973, showing ascending and expanding motions, has been recorded spectroscopically at Oslo Solar Observatory.The Ca ii H line yields broadening velocities ranging from 5 km s-1 to 20 km s-1. An extreme ratio of 1/30 was measured for line-broadening to expansion velocity.Flare activity succeeded the start of the observed disparition brusque phase of the prominence. The eruption is related to coronal disturbances recorded approximately 1 hr later by ATM, Skylab. 相似文献
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In this note we discuss observations of two eruptive prominences. We find evidence for twisting motions in the early stages of the eruption. This twisting may be caused by a mechanism recently discussed by Parker (1974) and by Jockers (1976) wherein a magnetic flux tube, part of which has expanded because of reduction of external pressure, readjusts the magnetic torque along its axis. 相似文献
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Yong?LinEmail author Jun?Elin?Wiik Oddbj?rn?Engvold Luc?Rouppe?Van Der?Voort Zoe?A.?Frank 《Solar physics》2005,227(2):283-297
The locations of barbs of quiescent solar filaments are compared with the photospheric/chromospheric network, which thereby serves as a proxy of regions with enhanced concentrations of magnetic flux. The study covers quiet regions, where also the photospheric network as represented by flow converging regions, i.e., supergranular cell boundaries, contain largely weak magnetic fields. It is shown that close to 65% of the observed end points of barbs falls within the network boundaries. The remaining fraction points into the inner areas of the network cells. This confirms earlier findings (Lin et al., Solar Physics, 2004) that quiescent filaments are basically connected with weaker magnetic fields in the photosphere below. 相似文献
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Oddbjörn Engvold 《Solar physics》1972,23(2):346-352
A study has been made of fine structure wavelength shift in the K line spectra from quiescent prominences. A persistent small scale motion is found in the prominence main body. In places where we see the characteristic thread like fine structure in the accompanying H filtergrams the average line-of-sight velocity amplitude is about 1 km s–1. A higher velocity ( 4 km s–1) is associated with a slightly coarser, mottled prominence fine structure. In the low lying regions, connecting the prominence body and the chromosphere, we do not detect any fine structure line shift (v 1/2 km s–1). 相似文献
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The solar transition region in the neighbourhood of prominences has been studied from observations with the Ultraviolet Spectrometer and Polarimeter of NASA's Solar Maximum Mission satellite. Dopplergrams from observations of the transition-region lines Civ 1548 Å and Siiv 1393 Å, which are formed at about 105 K, give velocity amplitudes typically in the range ± 15 km s-1. Prominences are found to be located very close to dividing lines between areas of up- and down-draughts in the transition-region. The observed pattern suggests that the 105 K gas flows take place within arcades of magnetic loops, which most likely are part of the supporting magnetic structure for the prominence matter. An additional band of blue-ward Doppler shifts is frequently seen close to quiescent prominences. This may be the source of outward flowing matter along the helmet streamers above filament channels. 相似文献
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