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We compare observations of type III impulsive radio bursts made at the Clark Lake Radio Observatory with high-spatial-resolution cinematographic observations taken at the Big Bear Solar Observatory. Use of the log-periodic radio interferometer allows us to localize the radio emission uniquely. This study concentrates on the particularly active region close to the limb on 22 May 1970. Sixteen of the 17 groups were associated with some H activity, 11 of them with the start of such activity.as of September 1972: Williams College-Hopkins Observatory, Williamstown, Massachusetts 01267. 相似文献
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Pasachoff Jay M. Babcock Bryce A. Russell Kevin D. Seaton Daniel B. 《Solar physics》2002,207(2):241-257
As a part of a study of the cause of solar coronal heating, we searched for high-frequency (1 Hz) intensity oscillations in coronal loops in the [Fexiv] coronal green line. We summarize results from observations made at the 11 August 1999 total solar eclipse from Râmnicu-Vâlcea, Romania, through clear skies. We discuss the image reduction and analysis through two simultaneous series of coronal CCD images digitized at 10 Hz for a total time of about 140 s. One series of images was taken through a 3.6 Å filter isolating the 5303 Å[Fexiv] coronal green line and the other through a 100 Å filter in the nearby K-corona continuum. Previous observations, described in Pasachoff et al. (2000), showed no evidence for oscillations in the [Fexiv] green line at a level greater than 2% of coronal intensity. We describe several improvements made over the 1998 eclipse that led to increased image clarity and sensitivity. The corona was brighter in 1999 with the solar maximum, further improving the data. We use Fourier analysis to search in the [Fexiv] channel for intensity oscillations in loops at the base of the corona. Such oscillations in the 1-Hz range are predicted as a result of density fluctuations from the resonant absorption of MHD waves. The dissipation of a significant amount of mechanical energy from the photosphere into the corona through this mechanism could provide sufficient energy to heat the corona. A Monte Carlo model of the data suggests the presence of enhanced power, particularly in the 0.75–1.0 Hz range, and we conclude that MHD waves remain a viable method for coronal heating. 相似文献
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Phillips K.J.H. Read P.D. Gallagher P.T. Keenan F.P. Rudawy P. Rompolt B. Berlicki A. Buczylko A. Diego F. Barnsley R. Smartt R.N. Pasachoff J.M. Babcock B.A. 《Solar physics》2000,193(1-2):259-271
The Solar Eclipse Coronal Imaging System (SECIS) is an instrument designed to search for short-period modulations in the solar corona seen either during a total eclipse or with a coronagraph. The CCD cameras used in SECIS have the capability of imaging the corona at a rate of up to 70 frames a second, with the intensities in each pixel digitised in 12-bit levels. The data are captured and stored on a modified PC. With suitable optics it is thus possible to search for fast changes or short-period wave motions in the corona that will have important implications for the coronal heating mechanism. The equipment has been successfully tested using the Evans Solar Facility coronagraph at National Solar Observatory/Sacramento Peak and during the 11 August 1999 eclipse at a site in north-eastern Bulgaria. The instrument is described and preliminary results are outlined. 相似文献
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We detected excess oscillatory power at 0.25–2.0 Hz in a coronal loop in the 1983 Indonesian total solar eclipse. In this second-generation experiment enlarging upon the work of Pasachoff and Landman (1984), we observed in two frequency channels, one coronal and one continuum, to monitor atmospheric and instrumental effects. We briefly discuss the effects of an oscillation near 1 Hz on the coronal heating problem.Visiting Colleague, Institute for Astronomy, University of Hawaii. 相似文献
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Scientific observations at total solar eclipses 总被引：1，自引：0，他引：1
Jay M. Pasachoff 《天体物理学报》2009,(6):613-634
The occasion of the longest totality of an eclipse in the 18 yr 11^1/3 d saros cycle leads to taking stock of the scientific value of ground-based eclipse observations in this space age. Though a number of space satellites from the U.S., Europe, Japan, and Russia study the Sun, scientists at eclipses can observe the solar chromosphere and corona at higher spatial resolution, at higher temporal resolution, and at higher spectral resolution than are possible aloft. Furthermore, eclipse expeditions can transport a wide variety of state-of-the-art equipment to the path of totality. Thus, for at least some years to come, solar eclipse observations will remain both scientifically valuable and cost-effective ways to study the outer solar atmosphere. 相似文献
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We present digitized photographs of the white-light solar corona taken during the total solar eclipse of 22–23 November, 1984, on both calibrated black-and-white film and on color film. Conditions on site in Hula, Papua New Guinea, were exceptionally clear. The color image was used to produce an isophotal map of the inner corona, from which a flattening coefficient of 0.23 was measured. The black-and-white image was enhanced through a digital radial filter. Our images are the best processed images available from the 1984 eclipse and so provide important data for synoptic observations. 相似文献