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Author name code: defeiter
ADS astronomy entries on 2022-09-14
author:de Feiter, L.D.
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Title: Evidence for magnetic energy storage in coronal active regions.
Authors: Krieger, A. S.; de Feiter, L. D.; Vaiana, G. S.
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.
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Title: The Aims of the Flare Build-up Study (Introduction)
Authors: de Feiter, L. D.
1976SoPh...47...15D Altcode:
No abstract at ADS
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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.
1976IAUTA..16b..13N Altcode:
No abstract at ADS
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Title: Elementary flare bursts.
Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C.
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.
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Title: Chromospheric Flares or Chromospheric Aurorae?
Authors: de Feiter, L. D.
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.
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Title: On the behaviour of the hydrogen Lyman series in flares
Authors: de Feiter, L. D.; Svestka, Z.
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 (N<SUB>1</SUB>), the electron density (n<SUB>e</SUB>)
and the electron temperature (T<SUB>e</SUB>). 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 N<SUB>1</SUB>, 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 N<SUB>1</SUB> determination on the highest
line resolvable in the spectrum.
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Title: Solar Flare X-Ray Measurements and Their Relation to Microwave
Bursts
Authors: de Feiter, L. D.
1975IAUS...68..283D Altcode:
No abstract at ADS
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Title: High-energy particle and photon emission of solar flares
Authors: de Feiter, L. D.
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.
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Title: Solar hard X-ray bursts and accelerated electrons in solar
flares.
Authors: de Feiter, L. D.
1975lein.conf...93D Altcode:
No abstract at ADS
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Title: Solar flare X-ray measurements and their relation to microwave
bursts.
Authors: de Feiter, L. D.
1975IAUS...68Q.283D Altcode:
No abstract at ADS
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Title: Solar flare X-ray measurements and their relation to microwave
bursts.
Authors: de Feiter, L. D.
1975IAUS...68R.283D Altcode:
No abstract at ADS
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Title: Book reviews
Authors: Kleczek, J.; de Feiter, L. D.; Tinbergen, J.; Elsässer,
H.; Sciama, D. W.; Dewhirst, D. W.; Hensberge, G.
1974SSRv...16..611K Altcode:
No abstract at ADS
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Title: Solar Flares as Sources of Energetic Particles
Authors: de Feiter, L. D.
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.
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Title: Integrated Solar Flare Observations
Authors: de Feiter, L. D.
1974cesra...4...13D Altcode:
No abstract at ADS
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Title: Time Profiles and Photon Spectra of Solar Hard X-rays
Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C.
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.
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Title: Some critical problems of solar flare research.
Authors: de Feiter, L. D.
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.
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Title: Hard X-ray observations of elementary flare bursts, and
their interpretation.
Authors: van Beek, H. F.; de Feiter, L. D.; de Jager, C.
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.
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Title: Solar Flares, Suprathermal Plasma Nodules, and Loop Prominences
Authors: de Feiter, L. D.; de Jager, C.
1973sari.conf...93D Altcode:
No abstract at ADS
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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.
1973spre.conf..777V Altcode:
No abstract at ADS
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Title: Superthermal Plasma Nodules and Their Relation to Solar Flares
Authors: De Feiter, L. D.; De Jager, C.
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.
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Title: Solar Flares
Authors: de Feiter, L.
1973lsp2.conf...55D Altcode:
No abstract at ADS
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Title: The Hard Solar X-Ray Spectrometer on Board the ESRO Td-1
a Satellite
Authors: van Beek, H. F.; de Feiter, L. D.
1973sari.conf..103V Altcode:
No abstract at ADS
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Title: Interplanetary Solar Phenomena
Authors: de Feiter, L. D.
1973sari.conf....1D Altcode:
No abstract at ADS
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Title: The Expected Behaviour of the Hydrogen Lyman Lines in Solar
Flares
Authors: Švestka, Z.; de Feiter, L. D.
1972SSRv...13..824S Altcode: 1972IAUCo..14..824S
No abstract at ADS
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Title: The Transient Highly Excited Solar Flare Plasma (invited Paper)
Authors: de Feiter, L. D.
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.
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Title: Summary of the Panel Discussions
Authors: de Feiter, L. D.
1972SSRv...13..361D Altcode:
No abstract at ADS
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Title: Introduction
Authors: de Feiter, L. D.
1972SSRv...13..197D Altcode:
No abstract at ADS
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Title: Epilogue by the Editors
Authors: Kremser, G.; de Feiter, L. D.
1972SSRv...13..365K Altcode:
No abstract at ADS
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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.
1972SoPh...23..501D Altcode:
No abstract at ADS
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Title: Neutron and gamma-ray emission from white-light flares.
Authors: de Feiter, L. D.; Svestka, Z.
1972spre.conf.1547D Altcode: 1972spre....2.1547D
No abstract at ADS
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Title: Abstracts of papers from other journals
Authors: Henoux, J. -C.; De Feiter, L. D.; Ambroš, P.; Pasachoff,
JAY M.
1972SoPh...22..252H Altcode:
No abstract at ADS
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Title: Abstracts of papers from other journals
Authors: De Feiter, L. D.; Vassilyeva, G.; Henoux, J. -C.; Ambrož,
Pavel
1971SoPh...20..517D Altcode:
No abstract at ADS
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Title: On the Flux of Gamma Rays from Solar Flares
Authors: De Feiter, L. D.
1971SoPh...19..207D Altcode:
No abstract at ADS
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Title: Abstracts of papers from other journals
Authors: Pasachoff, Jay M.; Henoux, J. -C.; de Feiter, L. D.
1971SoPh...17..277P Altcode:
No abstract at ADS
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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
1970SSRv...11..593D Altcode:
No abstract at ADS
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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.
1970SSRv...10..737D Altcode:
No abstract at ADS
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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.
1970SoPh...11..173U Altcode:
No abstract at ADS
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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.
1969SoPh....8..491S Altcode:
No abstract at ADS
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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.
1969SoPh....6..155P Altcode:
No abstract at ADS
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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.
1969AIQSY...3..229B Altcode:
No abstract at ADS
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Title: Book reviews
Authors: de Feiter, L. D.; de Jager, C.
1968SoPh....3..623D Altcode: 1968SoPh....3..623.
No abstract at ADS
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Title: Analysis of the Balmar spectrum of solar flares
Authors: de Feiter, Leendert Dirk
1966abss.book.....D Altcode: 1966QB526.F6F4.....
No abstract at ADS
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Title: Analysis of the Balmer spectrum of solar flares
Authors: de Feiter, Leendert Dirk
1966RAOU...18R....D Altcode:
No abstract at ADS
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Title: Analysis of the Balmer spectrum of solar flares
Authors: de Feiter, Leendert Dirk
1966PhDT........69D Altcode:
No abstract at ADS
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Title: On the Stark Broadening of High Balmer Lines Emitted by
Solar Flares
Authors: de Feiter, L. D.
1964NASSP..50...81D Altcode: 1964psf..conf...81D
No abstract at ADS
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Title: Time variation of electron density in a large solar flare
Authors: de Feiter, L. D.; Švestka, Z.
1964BAICz..15..117D Altcode:
No abstract at ADS
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Title: Details of the Relations between Type IV-Outbursts and
sc-Geomagnetic Storms
Authors: Roosen, J.; de Feiter, L. D.
1962JPSJS..17A..49R Altcode: 1962ICRC....7A..49R; 1962JPSJ...17A..49R; 1962PSJaP..17A..49R
No abstract at ADS
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Title: On Maximum of Cosmic-Ray Intensity prior to a Prebaisse-Effect
Authors: de Feiter, L. D.; Legrand, J. P.
1962JPSJS..17B.272D Altcode: 1962ICRC....7B.272D; 1962PSJaP..17B.272D; 1962JPSJ...17B.272D
No abstract at ADS
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Title: On the production of solar radio outbursts in different
centres of activity
Authors: de Feiter, L. D.; Fokker, A. D.
1961BAN....15..319D Altcode:
No abstract at ADS
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Title: The Cosmic Ray Flares of November 12 and 15, 1960
Authors: De Feiter, L. D.; Freon, A.; Legrand, J. P.
1961spre.conf..776D Altcode:
No abstract at ADS
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Title: The cosmic ray flares of Nov. 12 and 15. 1960.
Authors: Legrand, J. P.; de Feiter, L. D.; Freon, A.
1961PRNAA..64..325L Altcode: 1961RNAAS..64..325L
No abstract at ADS
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Title: Solar radio events and geomagnetic storms
Authors: De Feiter, L. D.; Fokker, A. D.; Van Lohuizen, H. P. Th.;
Roosen, J.
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.
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Title: The profiles of Hα in solar flares
Authors: de Feiter, L. D.
1960AnAp...23..970D Altcode:
No abstract at ADS
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Title: Association of Radio Outbursts with Solar Flares
Authors: de Feiter, L. D.; Fokker, A. D.; Roosen, J.
1959Natur.184..805D Altcode:
SEVERAL authors have paid attention to the association of radio
outbursts with solar flares, for example, Dodson<SUP>1</SUP> and
Loughhead, Roberts and McCabe<SUP>2</SUP>. 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.
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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.
1956sei..conf..272F Altcode:
No abstract at ADS
