Author name code: defeiter ADS astronomy entries on 2022-09-14 author:de Feiter, L.D. ------------------------------------------------------------------------ Title: Evidence for magnetic energy storage in coronal active regions. Authors: Krieger, A. S.; de Feiter, L. D.; Vaiana, G. S. Bibcode: 1976SoPh...47..117K Altcode: Examination of X-ray images obtained by the S-054 X-ray spectrographic telescope on Skylab shows the presence of some atypical X-ray emitting coronal structures in active regions which are not consistent with potential extrapolations of photospheric magnetic fields. Analysis of the observed temporal changes in the X-ray emitting active region structures demonstrates that the majority of these consist of brightness changes representing temperature (and perhaps, density) variations of the material in the loops. Title: The Aims of the Flare Build-up Study (Introduction) Authors: de Feiter, L. D. Bibcode: 1976SoPh...47...15D Altcode: No abstract at ADS Title: Solar activity (Activité solaire). Authors: Newkirk, G.; Dunn, R. B.; Mehltretter, P.; MacQueen, R.; Bonnet, R. M.; White, O. R.; Fokker, A. D.; Zwaan, C.; Bruzek, A.; Durrant, C.; Grossmann-Doerth, U.; Mehltretter, J. P.; Svestka, Z.; de Feiter, L. D.; Tandberg-Hanssen, E.; Howard, R.; Stix, M.; Pneuman, G. W.; Hundhausen, A. J.; Sawyer, C.; Simon, P. Bibcode: 1976IAUTA..16b..13N Altcode: No abstract at ADS Title: Elementary flare bursts. Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C. Bibcode: 1976spre.conf..819V Altcode: 1976spre.proc..819V Two hard X-ray flares observed on 2 and 7 August 1972 with the hard X-ray detector of the Utrecht Space Research Laboratory aboard ESRO's TD-1A satellite are examined in detail. It is shown that both flares can be decomposed completely into a number of individual Elementary Flare Bursts (EFB's) with no residual radiation left. For one and the same flare all EFB's seem to have approximately the same time profile but these profiles are different for the two flares investigated: the full widths at half maximum (FWHM) of the EFB's are 5 and 15 s respectively. Title: Chromospheric Flares or Chromospheric Aurorae? Authors: de Feiter, L. D. Bibcode: 1975SSRv...17..181D Altcode: This paper discusses some of the well-documented flare phenomena and possible analogies with magnetospheric substorm phenomena. Such analogies do exist, but also important differences. The combination of forces from magnetospheric and solar physicists will bring us closer to the understanding of these nearby examples of unstable cosmic plasmas. Title: On the behaviour of the hydrogen Lyman series in flares Authors: de Feiter, L. D.; Svestka, Z. Bibcode: 1975SoPh...41..415D Altcode: The Lyman spectrum of hydrogen has been computed for a number of flare models, characterized by the column density of hydrogen atoms in the ground state (N1), the electron density (ne) and the electron temperature (Te). Broadening by the thermal Doppler effect and by Stark effect has been accounted for. The source functions for the individual lines of the series have been derived from non-LTE calculations of the excitation in hydrogen flares. The aim of the investigation is to evaluate the use of the intensities in between two successive Lyman lines for a determination of the value for N1, which is a physical parameter of the flare for which only indirect determinations are available. Whilst in principle this method could give reliable results, its practical application meets with difficulties which hardly can be overcome. Therefore, one probably has to base the N1 determination on the highest line resolvable in the spectrum. Title: Solar Flare X-Ray Measurements and Their Relation to Microwave Bursts Authors: de Feiter, L. D. Bibcode: 1975IAUS...68..283D Altcode: No abstract at ADS Title: High-energy particle and photon emission of solar flares Authors: de Feiter, L. D. Bibcode: 1975iafe.rept...84D Altcode: Particle acceleration in solar flares is investigated, and examples of the apparent links between high-energy particle and photon flare emissions are presented. Energetic electromagnetic flare emissions are classified as thermal or quasi-thermal, impulsive, and prolonged nonthermal; effects of interplanetary-magnetic-field structure on the properties of energetic particles as observed near earth are summarized. General properties of soft X-ray bursts, EUV emissions, and their sources are described, the components of impulsive X-ray bursts are identified, and the role of energetic electrons in these events is examined. Effects of protons and nuclei in flare regions are discussed with respect to the production of positron emitters, neutral pi mesons, neutrons, excited nuclei, and gamma rays in nuclear reactions. Title: Solar hard X-ray bursts and accelerated electrons in solar flares. Authors: de Feiter, L. D. Bibcode: 1975lein.conf...93D Altcode: No abstract at ADS Title: Solar flare X-ray measurements and their relation to microwave bursts. Authors: de Feiter, L. D. Bibcode: 1975IAUS...68Q.283D Altcode: No abstract at ADS Title: Solar flare X-ray measurements and their relation to microwave bursts. Authors: de Feiter, L. D. Bibcode: 1975IAUS...68R.283D Altcode: No abstract at ADS Title: Book reviews Authors: Kleczek, J.; de Feiter, L. D.; Tinbergen, J.; Elsässer, H.; Sciama, D. W.; Dewhirst, D. W.; Hensberge, G. Bibcode: 1974SSRv...16..611K Altcode: No abstract at ADS Title: Solar Flares as Sources of Energetic Particles Authors: de Feiter, L. D. Bibcode: 1974SSRv...16....3D Altcode: In this paper a review is presented of the present status of our knowledge of solar flare phenomena with special emphasis on the production of suprathermal particles and their solar effects. Of these energetic particles electrons play an important role since they produce the X-ray and radiobursts observed during many flares. Also, during their slowing down to thermal energies they contribute to the heating of localized regions in the solar atmosphere, through energy exchange with the ambient electrons. Observable radiations of energetic protons, and other nuclei, are produced through nuclear interactions leading to the emissions of gamma-ray lines. Detectable fluxes of these gamma-ray lines are produced only in the most powerful flares. Also the nuclei that enter into deeper layers of the solar atmosphere transfer most of their kinetic energy to the ambient plasma. Title: Integrated Solar Flare Observations Authors: de Feiter, L. D. Bibcode: 1974cesra...4...13D Altcode: No abstract at ADS Title: Time Profiles and Photon Spectra of Solar Hard X-rays Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C. Bibcode: 1974ASSL...42..533V Altcode: 1974cimo.symp..533V With a spectrometer aboard the ESRO TD-1A satellite, time profiles and photon spectra of solar X-rays have been observed in the energy range above 24 keV. Most of the X-ray bursts studied thus far appear to consist of numerous short-lived spikes with rise and decay times of a few seconds. Such spikes, called 'Elementary Flare Bursts' (EFB's) cluster together in large numbers and constitute the conventional high energy flare. The form of the photon spectra could be determined very accurately and was in all cases of the power-law type. For the Aug. 4, 1972 flare, the photon spectra appear to be combinations of two power-law spectra; for the lower energies the spectral coefficient is smaller than for the higher energies. The transition energy is about 60 keV. Title: Some critical problems of solar flare research. Authors: de Feiter, L. D. Bibcode: 1974spre.conf..413D Altcode: 1974spre.meet..413D Some problems of current interest in the research of energetic solar flare phenomena are reviewed with the aim of determining the open questions in this field. Possible directions in which the solutions may be found are indicated. In this context the following problems are discussed: the need for a determination of the magnetic field structure in the chromospheric and coronal parts of an active region before, during and after the occurrence of a flare, the 'thermal' flares and their differences with respect to the impulsive flares, the energetic relation between the non-thermal and the thermal components of the high-energy flare, the implications of repetitive flare instabilities and continuous acceleration models, the nuclear gamma rays and neutrons as manifestations of the solar effects of accelerated nuclei. Title: Hard X-ray observations of elementary flare bursts, and their interpretation. Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C. Bibcode: 1974spre.conf..447V Altcode: 1974spre.meet..447V Recent observations of solar hard X-ray bursts, performed with high time resolution aboard the ESRO TD-1A satellite, show that often these bursts consist of numerous short-lived spikes with rise and decay times of the order of a few seconds. It is argued that these spikes, which are called elementary flare bursts (EFB), are the essential physical phenomena, which, clustered together in large numbers, constitute the conventional high-energy flare. For some cases studied it is found that the rise and decay times can be as low as 1 to 2 seconds; individual points deviate only slightly from this average value. These times do not depend on the photon energy; this seems to indicate that the EFBs occur at a fairly low level in the chromosphere (less than or equal to 1500 km above the photosphere). For one particular case studied this conclusion is corroborated by the observation of short-lived flashes as observed optically with an interference filter centered at 3835 A. In this region a considerable part of the ambient electrons are accelerated to energies of several tens of kiloelectron volts. Title: Solar Flares, Suprathermal Plasma Nodules, and Loop Prominences Authors: de Feiter, L. D.; de Jager, C. Bibcode: 1973sari.conf...93D Altcode: No abstract at ADS Title: First results of the solar hard X-ray spectrometer on board the ESRO TD-1A satellite. Authors: van Beek, H. F.; de Feiter, L. D. Bibcode: 1973spre.conf..777V Altcode: No abstract at ADS Title: Superthermal Plasma Nodules and Their Relation to Solar Flares Authors: De Feiter, L. D.; De Jager, C. Bibcode: 1973SoPh...28..183D Altcode: We define superthermal plasma nodules as bright points (diameter ≲ 20″), visible on high resolution X-ray heliograms. Flares appear to show a strong tendency to occur at the places of these nodules. There are indications that (part of) the hot plasma produced by consecutive flares is accumulated and confined in the superthermal plasma nodules, and that with increasing energy content of a nodule the probability for a drastic change of its magnetic structure increases, thus reducing the possibility for more flares to occur. Title: Solar Flares Authors: de Feiter, L. Bibcode: 1973lsp2.conf...55D Altcode: No abstract at ADS Title: The Hard Solar X-Ray Spectrometer on Board the ESRO Td-1 a Satellite Authors: van Beek, H. F.; de Feiter, L. D. Bibcode: 1973sari.conf..103V Altcode: No abstract at ADS Title: Interplanetary Solar Phenomena Authors: de Feiter, L. D. Bibcode: 1973sari.conf....1D Altcode: No abstract at ADS Title: The Expected Behaviour of the Hydrogen Lyman Lines in Solar Flares Authors: Švestka, Z.; de Feiter, L. D. Bibcode: 1972SSRv...13..824S Altcode: 1972IAUCo..14..824S No abstract at ADS Title: The Transient Highly Excited Solar Flare Plasma (invited Paper) Authors: de Feiter, L. D. Bibcode: 1972SSRv...13..827D Altcode: 1972IAUCo..14..827D Recent observations of the energetic particles produced in solar flares indicate that the production of electrons, with energies up to about 100 keV, is a fairly common feature of small flares. In those flares the acceleration of protons and other nuclei does not extend beyond about 1 MeV. The X-ray emission often exhibits two distinct components of which the first one is produced by non-thermal, the second by thermal electrons through bremsstrahlung collisions with the ambient ions. Along with these X rays, radio emission, in the microwave region, is observed. This radio emission is usually interpreted as due to gyrosynchrotron radiation from the same electrons. In this review a discussion is presented of the processes occurring in solar flares with special reference to the acceleration and radiation processes. Title: Summary of the Panel Discussions Authors: de Feiter, L. D. Bibcode: 1972SSRv...13..361D Altcode: No abstract at ADS Title: Introduction Authors: de Feiter, L. D. Bibcode: 1972SSRv...13..197D Altcode: No abstract at ADS Title: Epilogue by the Editors Authors: Kremser, G.; de Feiter, L. D. Bibcode: 1972SSRv...13..365K Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: De Feiter, L. D.; Pasachoff, Jay M.; Vassilyeva, G.; Gussmann, E. A.; Vassilyeva, G. J.; Henoux, J. -C.; Uchida, Y.; Namba, O. Bibcode: 1972SoPh...23..501D Altcode: No abstract at ADS Title: Neutron and gamma-ray emission from white-light flares. Authors: de Feiter, L. D.; Svestka, Z. Bibcode: 1972spre.conf.1547D Altcode: 1972spre....2.1547D No abstract at ADS Title: Abstracts of papers from other journals Authors: Henoux, J. -C.; De Feiter, L. D.; Ambroš, P.; Pasachoff, JAY M. Bibcode: 1972SoPh...22..252H Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: De Feiter, L. D.; Vassilyeva, G.; Henoux, J. -C.; Ambrož, Pavel Bibcode: 1971SoPh...20..517D Altcode: No abstract at ADS Title: On the Flux of Gamma Rays from Solar Flares Authors: De Feiter, L. D. Bibcode: 1971SoPh...19..207D Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: Pasachoff, Jay M.; Henoux, J. -C.; de Feiter, L. D. Bibcode: 1971SoPh...17..277P Altcode: No abstract at ADS Title: Book reviews Authors: de Graaf, T.; Houziauk, L.; de Pater, A. D.; de Feiter, L. D.; Hundhausen, A. J.; Veldkamp, J.; Axford, W. Ian Bibcode: 1970SSRv...11..593D Altcode: No abstract at ADS Title: Book reviews Authors: de Jager, C.; King-Hele, D. G.; Heise, John; ĹEna, P.; Somoza, R.; Lindblad, Per Olof; Ritchey, H. W.; de Feiter, L. D. Bibcode: 1970SSRv...10..737D Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: Uchida, Y.; Gussmann, E. A.; De Feiter, L. D.; Henoux, J. -C.; Stepanyan, N. N.; Pasachoff, Jay. M. Bibcode: 1970SoPh...11..173U Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: Stepanyan, N.; Pasachoff, Jay M.; Ambrož, P.; Vassilyeva, G.; Henoux, J. -C.; Fokker, A. D.; De Feiter, L. D.; Gussmann, E. A.; Uchida, Y.; Namba, O. Bibcode: 1969SoPh....8..491S Altcode: No abstract at ADS Title: Abstracts of papers from other journals Authors: Pasachoff, Jay M.; Gussmann, E. A.; Stepanyan, N. N.; de Feiter, L. D.; Uchida, Yutaka; Švestka, Z.; Vassilyeva, G. J. Bibcode: 1969SoPh....6..155P Altcode: No abstract at ADS Title: On the development and activity of the active region associated with the proton flare event of July 1966: Summary of observations and conclusions. Authors: Banin, V.; de Feiter, L. D.; Fokker, A. D.; Martres, M. -J.; Pick, M. Bibcode: 1969AIQSY...3..229B Altcode: No abstract at ADS Title: Book reviews Authors: de Feiter, L. D.; de Jager, C. Bibcode: 1968SoPh....3..623D Altcode: 1968SoPh....3..623. No abstract at ADS Title: Analysis of the Balmar spectrum of solar flares Authors: de Feiter, Leendert Dirk Bibcode: 1966abss.book.....D Altcode: 1966QB526.F6F4..... No abstract at ADS Title: Analysis of the Balmer spectrum of solar flares Authors: de Feiter, Leendert Dirk Bibcode: 1966RAOU...18R....D Altcode: No abstract at ADS Title: Analysis of the Balmer spectrum of solar flares Authors: de Feiter, Leendert Dirk Bibcode: 1966PhDT........69D Altcode: No abstract at ADS Title: On the Stark Broadening of High Balmer Lines Emitted by Solar Flares Authors: de Feiter, L. D. Bibcode: 1964NASSP..50...81D Altcode: 1964psf..conf...81D No abstract at ADS Title: Time variation of electron density in a large solar flare Authors: de Feiter, L. D.; Švestka, Z. Bibcode: 1964BAICz..15..117D Altcode: No abstract at ADS Title: Details of the Relations between Type IV-Outbursts and sc-Geomagnetic Storms Authors: Roosen, J.; de Feiter, L. D. Bibcode: 1962JPSJS..17A..49R Altcode: 1962ICRC....7A..49R; 1962JPSJ...17A..49R; 1962PSJaP..17A..49R No abstract at ADS Title: On Maximum of Cosmic-Ray Intensity prior to a Prebaisse-Effect Authors: de Feiter, L. D.; Legrand, J. P. Bibcode: 1962JPSJS..17B.272D Altcode: 1962ICRC....7B.272D; 1962PSJaP..17B.272D; 1962JPSJ...17B.272D No abstract at ADS Title: On the production of solar radio outbursts in different centres of activity Authors: de Feiter, L. D.; Fokker, A. D. Bibcode: 1961BAN....15..319D Altcode: No abstract at ADS Title: The Cosmic Ray Flares of November 12 and 15, 1960 Authors: De Feiter, L. D.; Freon, A.; Legrand, J. P. Bibcode: 1961spre.conf..776D Altcode: No abstract at ADS Title: The cosmic ray flares of Nov. 12 and 15. 1960. Authors: Legrand, J. P.; de Feiter, L. D.; Freon, A. Bibcode: 1961PRNAA..64..325L Altcode: 1961RNAAS..64..325L No abstract at ADS Title: Solar radio events and geomagnetic storms Authors: De Feiter, L. D.; Fokker, A. D.; Van Lohuizen, H. P. Th.; Roosen, J. Bibcode: 1960P&SS....2..223D Altcode: On the basis of a 24-hr patrol of solar radio noise established since the beginning of the International Geophysical Year, an identification is attempted of those solar flares which, on account of their associated radio responses, most probably were the cause of a geomagnetic storm. The cases for which we think the identification to be reliable are listed. It has appeared that great integrated intensity of the radio outburst at centimeter, decimeter and meter wavelengths is the primary criterion for identifying the solar flares responsible. Most of these giant radio outbursts, to which we assigned the "radio importance" figure 3 +, belong to the so-called type IV. Only a minor fraction of these events were accompanied by slow-drift bursts of type II. Of the importance 3 + radio outbursts about 60 per cent are clearly associated with the subsequent sudden commencement of a geomagnetic storm. Conversely, about 50 per cent of the sudden commencements of a storm can be related to an important radio event. Some reasons, why in a particular case the storm-outburst association may fail to exist, are mentioned. Title: The profiles of Hα in solar flares Authors: de Feiter, L. D. Bibcode: 1960AnAp...23..970D Altcode: No abstract at ADS Title: Association of Radio Outbursts with Solar Flares Authors: de Feiter, L. D.; Fokker, A. D.; Roosen, J. Bibcode: 1959Natur.184..805D Altcode: SEVERAL authors have paid attention to the association of radio outbursts with solar flares, for example, Dodson1 and Loughhead, Roberts and McCabe2. Outstanding flare events are very commonly accompanied by a radio event at decimeter and/or metre wave-lengths; but only a minor fraction of the less-important flares produce a distinctive radio event. Title: Eclipse observations of solar radio-frequency radiation on 200, 545 3000, and 9100 Mc/s Authors: Fokker, A. D.; de Munck, J. C.; de Feiter, L. D. Bibcode: 1956sei..conf..272F Altcode: No abstract at ADS