Download or read book The Structure of Solar Active Regions as Inferred from Multifrequency VLA Observations written by Angelos Vourlidas and published by . This book was released on 1993 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Very Large Array V L A Observations of Solar Active Regions written by Kenneth R. Lang and published by . This book was released on 1979 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: High resolution radio wavelength observations of solar active regions indicate ever present, fine scale features whose high degree of circular polarization reflects the magnetic field structure in the solar corona. Changes in this structure may trigger major flare eruptions in solar active regions which create geophysical disturbances and disrupt terrestrial communication and surveillance systems. In this paper we discuss the basic techniques of using the Very Large Array (V.L.A.) to obtain radio wavelength observations (6 cm) maps of solar active regions. It is shown that the V.L.A. coverage in the u-v plane (the Fourier plane of the active region's brightness distribution) is much more complete than the u-v coverage available with other synthesis telescopes or with interferometers with east-west baseline configurations. Calibration procedures for V.L.A. observations of the Sun are discussed, and maps of two solar active regions are presented. For the first time radio wavelength maps of coronal magnetic field structures have been obtained with angular resolutions comparable to those obtained at optical wavelengths when viewing the cooler, lower lying photosphere.

Download or read book Structure and Development of Solar Active Regions written by K.O. Kiepenheuer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: K. O. KIEPENHEUER ( Fraunhofer Institut, Freiburg i. Br., Germany) The present symposium, to my knowledge the largest ever held in the field of solar research (170 astronomers from 21 countries) was held in the building of the Hun garian Academy of Sciences in Budapest from September 4 to 8, 1967. It was the 35th symposium organized and sponsored by the International Astronomical Union. The majority of participants were financedfrom national sources. The Organizing Commit tee consisted of K. O. Kiepenheuer (Chairman), L. Davis, L. Dezso (Local Organizer), A.D. Fokker, R. Michard, A.B. Severny, H.J. Smith, Z. Svestka, and H. Tanaka. In order to ensure prompt publication, the manuscripts had to be supplied by the authors 1 month after the meeting. The discussions have been recorded on tape. Their reproduction in this book, however, is based almost completely on the contributors' writing down their comments and questions on the spot. Two special projects have been reported and discussed shortly during the sym posium: The world wide project 'Cooperative Study of Solar Active Regions' (CSSAR) organized by Dr. R. Michard, under the auspices of the IAU, which has put at the disposal of our solar community a precious observing material on Active Regions over a period of 6 months.

Download or read book V L A Observations of Solar Active Regions I The Slowly Varying Component written by Marcello Felli and published by . This book was released on 1980 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Large Array (V.L.A.) synthesis maps of the total intensity and the circular polarization of the active region AR 2032 at 6 cm wavelength are presented and compared with H alpha photographs and Zeeman effect magnetograms of the same region with second-of-arc accuracy. The maps indicate that the radio emission is dominated by a small (approx. 30 inches), bright (10 to the 6th power K), circularly polarized (40% to 100%) source whose detailed morphological features are correlated with the chromospheric plage seen as bright regions on the H alpha photographs. The large brightness temperatures of the radio features indicate that they are the coronal counterparts of the chromospheric plage. The regions of enhanced emission at 6 cm wavelength exhibited substantial structural changes on a time scale of one day, and these changes were correlated with similar changes in the chromospheric plage. Weak or undetectable radio emission was found in the regions directly overlying sunspots; but two small (approx. 10 inches), bright (approx. 10 to the 6th power K) radio sources were found at the outer edges of one sunspot where the magnetic field gradient is large. Although the degree of circular polarization varied from 40% to 100% in different regions of the dominant, plage-associated source, the entire source had one magnetic polarity and the general magnetic structure was correlated with the longitudinal magnetic field seen on magnetograms of the lower lying photosphere.

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this jOint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 40 (thesis year 1995) a total of 10,746 thesis titles from 19 Canadian and 144 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 40 reports theses submitted in 1995, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

Download or read book VLA observations of a solar active region at 6 2 and 3 5 cm wavelenght compared with model calculations written by and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book VLA Observations of a Solar Active Region at 6 2 and 3 5 Cm Wavelength Compared with Model Calculations written by Joachim Hildebrandt and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Very Large Array Observations of Solar Active Regions IV Structure and Evolution of Radio Bursts from 20 Cm Loops written by Robert F. Willson and published by . This book was released on 1983 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Very Large Array (VLA) has been used to study the structure and evolution of six solar bursts near 20 cm wavelength. In most cases the burst emission has been resolved into looplike structures with total lengths, approx, 3 x 10 to the minus 9th power cm, brightness temperatures approx. 10 to the 7th to 8th power K and degress of circular polarization approx. or 90%. Changes in the total intensity and circular polarization of the bursts occur on timescales as short as ten seconds. The individual peaks of one multiple component burst originated in different locations within a magnetically complicated region. Preburst heating and circular polarizaton changes respectively occurred minutes before the onset of the impulsive phase of two bursts. In one case a loop system emerged in the vicinity of the impulsive source, and two adjacent loop systems may have emerged and triggered the burst.

Download or read book Simultaneous Solar Maximum Mission Smm and Very Large Array Vla Observations of Solar Active Regions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-27 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun. Willson, Robert F. Unspecified Center NASA-CR-187907, NAS 1.26:187907 NAG5-501...

Download or read book Theoretical and Observational Problems Related to Solar Eclipses written by Z. Mouradian and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NATO ARW on the problems of ground-based observations of Solar Eclipses was held in Sinaia (Romania) between 1 and 5 June 1996. The Workshop was divided into seven sessions, in which 17 papers were given, by key speakers, along with 30 oral presentations. Additionally, 30 posters were presented. This issue contains only the invited and oral papers. The posters are to be published in a special issue of the Romanian Astronomical Journal. The contributions were based on our present knowledge of solar corona physics and on the perspectives for future total eclipse observations, focussing especially on that of August 11, 1999, which will be the last eclipse of the century. The workshop sessions reviewed the results of past eclipse observations, coronal hot and cold structures, coronal heating, public education, and instrumental problems. At the end of the meeting a fruitful general discussion drew out problems to be studied and techniques to be used for forthcoming observations. Posters completed the workshop contributions.

Download or read book Very Large Array Observations of the Sun with Related Observations Using the SMM Solar Maximum Mission Satellite written by and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple Wavelength Observations of Flaring Active Regions; Very Large Array Observations of Solar Active Regions III. Multiple Wavelength Observations. High-Resolution Observations of Solar Radio Bursts at 2, 6, and 20 cm Wavelength; The Circularly Polarized Sun at 12.6 cm Wavelength; Bright, Rapid, Highly Polarized Radio Spikes from the M Dwarf AD. Leonis; Possible Detection of Thermal Cyclotron Lines from Small Sources within Solar Active Regions. Observations of Preburst Heating and Magnetic Field Changes in a 20 cm Loop; The Structure of a Solar Active Region from RATAN-600 and Very Large Array Observations; The Solar-Stellar Connection; Short Term Prediction of Solar Bursts - Radio Wavelength Precursors; VLA Observations of Flare Build Up in Coronal Loops on the Sun and Solar Type Stars; VLA Observations of Narrow-Band Decimetric Burst Emission; VLA Observations of Solar Active Regions at Closely Spaced Frequencies: Evidence for Thermal Cyclotron Line Emission; VLA Observations of Compact, Variable Sources on the Sun; Flare Stars and Solar Bursts; High Resolution In Time and Frequency; Coronal Plasmas On The Sun and Nearby Stars; Coronal Diagnostics; Narrow-Band; Millisecond Radio Spikes From the Dwarf M Flare Star AD Leonis; VLA Observations of a Solar Noise Storm. (JHD).

Download or read book Literature 1984 Part 2 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 928 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar Active Region Evolution written by National Solar Observatory/Sacramento Peak. Summer Workshop and published by . This book was released on 1994 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar and Space Weather Radio Physics written by Bin Chen and published by Frontiers Media SA. This book was released on 2021-07-28 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Literature 1988 Part 1 written by U. Esser and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ...The abstracts are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews#1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine#2

Download or read book The Sun in Time written by Charles Philip Sonett and published by University of Arizona Press. This book was released on 1991 with total page 1040 pages. Available in PDF, EPUB and Kindle. Book excerpt: An interdisciplinary approach to solar physics, as eighty-nine contributors trace the evolution of the Sun and provide a review of our current understanding of both its structure and its role in the origin and evolution of the solar system.