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 Technical Abstract Bulletin written by and published by . This book was released on 1981 with total page 206 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 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 Reprints National Radio Astronomy Observatory Green Bank W Va written by National Radio Astronomy Observatory (U.S.) and published by . This book was released on 1973 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Literature 1981 Part 1 written by Siegfried Böhme and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 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 Literature 1983 Part 1 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 825 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 33 records literature published in 1983 and received before August 1, 1983. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organizations, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Mona El-Choura, Ms. Monika Kohl, and Ms. Sylvia Matyssek. Mr. Martin Schlotelburg and Mr. Ulrich Uberall supported our task by careful proofreading. It is a pleasure to thank them all for their encouragement. Heidelberg, September 1983 The Editors Contents Introduction . . . . . . . . . . . . 1 Concordance Relation: ICSU-AB-AAA 3 Abbreviations 10 Periodicals, Proceedings, Books, Activities 001 Periodicals . . . . . . . . . . . 15 002 Bibliographical Publications, Documentation, Catalogues, Atlases 47 003 Books ...... . 51 004 History of Astronomy 58 005 Biography . . 64 006 Personal Notes 65 007 Obituaries . . .

Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1982 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

Download or read book Reprint written by and published by . This book was released on 1958 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Literature 1981 Part 2 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 803 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 1988 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Literature 1985 Part 2 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 1106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation ofthe literatme concerning all aspects of astronomy, astrophysics, and their border fields. lt is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 40 records literatme published in 1985 and received before February 15, 1986. Some older documents which we received late and which arenot surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was dorre by means of computers. The recording was dorre by om technical staff members Ms. Helga Ballmann, Ms. Mona El-Choura (t), Ms. Monika Kohl, Ms. Sylvia Matyssek. Ms. Karirr Burkhardt, Ms. Susanne Schlötelbmg, Mr. Mar tin Schlötelburg, and Mr. Stefan Wagner supported om task by careful proof reading. lt is a pleasure to thank them all for their encomagement.