explanation blue bibcodes open ADS page with paths to full text
Author name code: hoangh-bin
ADS astronomy entries on 2022-09-14
=author:"Hoang-Binh, D."
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Title: The “on the energy shell” simplification of the impulse
approximation in Rydberg atom-neutral collisions
Authors: Hoang-Binh, D.; van Regemorter, H.
1999AIPC..467..336H Altcode: 1999sls..conf..336H
Three types of calculations are compared according to the approximations
used for the (e+B) scattering amplitude fe(q-->q<SUP>'</SUP>):
(i) Exact impulse approximation (without any further approximation);
(ii) Impulse approximation+“on the energy shell” approximation; (iii)
Impulse approximation+“on the energy shell” approximation+“scattering
length” approximation. Preliminary results have been obtained for
Na(n,l)+Ar collisions, suggesting that the “on the energy shell”
approximation breaks down for large momentum transfers Q.
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Title: On the shifts of magnesium Rydberg lines in the solar infrared
spectrum.
Authors: Hoang-Binh, D.
1994A&A...286..607H Altcode:
New theoretical data for calculating the widths and shifts of solar
high-l Rydberg lines of neutral magnesium are reported. The line
shifts measured by Chang & Schoenfeld (1991) have been reanalysed
to obtain mean values of the electron densities in the regions where
the lines are formed. lt is found that, on the assumption that the
shifts due to interaction with neutral hydrogen atoms are negligible,
the lines are formed in a photospheric layer of about 200 km thick,
at heights between 150 and 350 km, and electron densities between 1.5
10^12^ and 6.6 10^12^ cm^-3^.
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Title: On the Ion Broadening of the 12 MU M lines of Atomic Magnesium
Authors: Hoang-Binh, D.; van Regemorter, H.
1994IAUS..154..353H Altcode:
No abstract at ADS
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Title: New Atomic Data for MG I Lines
Authors: Hoang-Binh, D.
1994IAUS..154..347H Altcode:
No abstract at ADS
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Title: Stark broadening theory of solar Rydberg lines in the
far-infrared spectrum
Authors: van Regemorter, H.; Hoang-Binh, D.
1993A&A...277..623V Altcode:
Line broadening theory is revisited to obtain simple formulae,
in the specific case of isolated lines, resulting from transitions
between nearly degenerate states of atomic magnesium. Both the widths
and shifts, due to collisions with electrons and positive ions,
are obtained without any elaborate calculations for all the Rydberg
lines (n‧, l‧) → (n,l‧+1), (5≤n‧≤ 1O n‧≤n<11,
l>3), listed by Jefferies (1991). Validity conditions of the
formulae are given for all the transitions under study. <P />It is
shown that inelastic weak collisions usually dominate the widths,
and that adiabatic ion collisions always dominate the shifts and thus
determine their signs. The shifts appear as good diagnostics; e.g. for
the peculiar case of the 6h-7i line near 12 μm, good agreement with
observations is obtained for electron and ion densities close to those
in the line forming region.
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Title: Multiplet oscillator strengths for excited atomic magnesium
Authors: Hoang-Binh, D.
1993A&AS...97..769H Altcode:
Transitions between excited terms of the 1,3S, 1,3P0, 1,3D, 1,3F0,
and 1,3G manyfolds of atomic magnesium have been calculated using
the Coulomb approximation. The principal quantum numbers of the lower
terms range from about 4 to 50.
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Title: On the formation of the solar emission lines near 12 microns
Authors: Hoang-Binh, D.
1991A&A...241L..13H Altcode:
An analysis of the populations of Rydberg states in the solar atmosphere
is presented. In contrast to the calculations of Lemke and Holweger
(1987) concerning Mg I, it is found that 7h is slightly overpopulated
relative to 6g in the upper photosphere. This implies an enhancement of
the stimulated emission in the 7h-6g line. The results are consistent
with the observation of an emission core in the lines 7h-6g and 7i-6h
of neutral magnesium (Brault and Noyes, 1983).
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Title: The level populations of hydrogen at high principal quantum
numbers.
Authors: Wilson, T. L.; Filges, L.; Hoang-Binh, D.; Stark, A. A.
1990A&A...238..331W Altcode:
An empirical study of high lying level populations of atomic hydrogen,
based on measurements of Delta-n = 1 transitions from the principal
quantum numbers n = 90, 65 and 41 has been carried out for the H II
region NGC 2024. A model for the electron density and temperature
distributions of this source is presented. For the central 1.8 arcsec
(FWHP) part of the source, the average value of the electron temperature
is 7400 K + or - 500 K. The departure coefficients from the 'standard'
theory (Brocklehurst 1970) fit better than the departure coefficients
of Hoang-Binh (1983). The latter include a direct interaction between
the populations and photons from the ionizing star of the high n levels
(Lyman pumping). Reasons for the non-detection of Lyman pumping effects
is NGC 2024 are discussed.
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Title: An exact calculation of hydrogenic radial integrals and
oscillator strengths, for principal quantum numbers up to N equal
to about 1000
Authors: Hoang-Binh, D.
1990A&A...238..449H Altcode:
We present a simple method for calculating easily and accurately the
Gordon formula. Exact values obtained for transitions between very high
Rydberg states have allowed a check on the accuracy of approximate
expressions derived from quasi-classical theory. The dependence
of the dipole radial integral on angular momenta is investigated in
detail. Simple formulae for the most important transitions in the Lyman,
Balmer, Paschen, ... series are given.
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Title: The Broadening of Radio Recombination Lines by Ion Collisions:
New Theoretical Results
Authors: Hoang-Binh, D.
1990ASSL..163...51H Altcode: 1989rrl..conf...51H; 1990IAUCo.125...51H; 1990rrly.conf...51H
No abstract at ADS
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Title: Ion-collision broadening of solar lines in the far-infrared
and submillimeter spectrum
Authors: Hoang-Binh, D.; Brault, P.; Picart, J.; Tran-Minh, N.;
Vallee, O.
1987A&A...181..134H Altcode:
The authors give new theoretical data for calculating the ion impact
broadening of solar far-infrared and submillimeter lines. These are more
accurate than, and should be preferred to data extrapolated directly
from Griem's (1967) work on radio recombination lines. The variation of
the line width as a function of the upper level of the transition has
also been investigated. It may be a potentially important diagnostic
tool for determining the physical conditions in the solar atmosphere.
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Title: Lyman line pumping and the modelling of H II regions
Authors: Hoang-Binh, D.
1986A&A...156..393H Altcode:
The author shows that Lyman line pumping (Hoang-Binh, 1983) reduces
the maser action in radio recombination lines emitted by H II
regions. This effect is equivalent to an increase of the electron
density N<SUB>e</SUB> without increasing the electron impact
broadening. In the modelling of H II regions by means of radio
line data, the variation of the parameter N<SUB>e</SUB> could be
significantly influenced by this pump mechanism.
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Title: Observations of radio recombination lines in the
millimeter-wave spectrum of Orion A.
Authors: Hoang-Binh, D.; Encrenaz, P.; Linke, R. A.
1985A&A...146L..19H Altcode:
The authors have observed the H 42α, 40α, 39α, 52β, 57γ, and
60γ lines in the direction of the molecular cloud in Orion A. From
the alpha line data, the derived values of the electron temperature,
assuming local thermodynamic equilibrium (LTE), are close to 10000K,
significantly higher than values ≅8500K, inferred from optical
studies. The authors interpret this as an evidence for a significant
deviation from LTE. This is confirmed by the analysis of the higher
order lines, and is consistent with the recent results of Wilson and
Pauls (1984). The importance of observations in the millimeter-wave
spectrum is discussed.
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Title: On a cosmic alphabet.
Authors: Hoang-Binh, D.
1985IAUS..112..493H Altcode:
The choice of frequencies for SETI has been discussed by many
authors. The author points out that the line spectrum provided by the
hydrogen (H) atom is very rich, and covers a large spectral domain,
from the ultraviolet to radio wavelengths. Since the H frequencies
are universally known, a "cosmic alphabet" could be constructed with
them. In a mono-frequency search for artificial radio signals, the
frequency of the H166 alpha line, 1425 MHz, might be a good substitute
for the frequency 1420 MHz of the H 21 cm line. In a multi-frequency
search, the frequencies of the prominent Hn alpha lines near H 21 cm
might be interesting.
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Title: Radiative excitation and the intensities of radio recombination
lines.
Authors: Hoang-Binh, D.
1983A&A...121L..19H Altcode:
The present investigation of the influence of the absorption of
stellar Lyman line photons on the population of highly excited states
of H in H II regions indicates that, for hot ionizing stars with an
effective temperature of more than 50,000 K, radiative excitation is
unimportant. Radiative excitation is more efficient for cooler stars,
of less than 40,000 K, and if the Lyman jump is sufficiently sharp,
it may become an important process at stellar temperatures of less
than 35,000 K. It is also found that, in nebulae excited by stars
of spectral type later than about O6, the contribution of radiative
excitation to radio recombination line intensities is not negligible.
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Title: On solar hydrogen lines in the far-infrared and submillimeter
spectrum
Authors: Hoang-Binh, D.
1982A&A...112L...3H Altcode:
Strength of H n-alpha lines, where n ranges from 5 to 20 have been
evaluated, using a recent model of the solar chromosphere. It is
found that they are much stronger than coronal ions lines, formed
by the process of dielectronic recombination; and their wavelength
dependence is strongly affected by pressure broadening. Observation of
these lines may provide useful diagnostics of the physical conditions
in the chromosphere, as well as valuable information on the behavior
of atoms in high Rydberg states.
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Title: The Frequency Dependence of the Carbon Recombination Line
Authors: Hoang-Binh, D.; Walmsley, C. M.
1974A&A....35...49H Altcode:
Summary. Current radio observations of the carbon line clouds are used
to derive their physical parameters. b factors are calculated for a low
temperature gas and the results are compared with those of previous
authors. A comparison is then made of the line intensities observed
as a function of frequency with those expected on the basis of simple
theoretical models. It is found that for the thr&e most studied
sources, the best fit to the observations is obtained if the emission
is mainly due to spontaneous transitions. An electron density of 10 and
a kinetic temperature of 100 K are the approximate parameters of the
best fitting models. Key words: recombination line - H I cloud b factors
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Title: Physical parameters in carbon line regions
Authors: Walmsley, M.; Hoang-Binh, D.
1974MmSAI..45..171W Altcode:
The paper describes attempts to fit the frequency dependence of
the carbon line strength from various regions for which a dilution
correction to each observation was necessary because a simple point
source model did not give a good fit for high frequency measurements. In
one model, a considerable contribution to line strength comes from
stimulation of the background continuum, giving a very steep dependence
on frequency which is not observed. Fits may be obtained, however,
for models in which the main contribution to the line strength comes
from spontaneous emission.
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Title: Mean electron density of NGC 7027 inferred from H 85alpha
line data.
Authors: Hoang-Binh, D.
1972saim.conf..365H Altcode:
No abstract at ADS
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Title: The broadening of radio recombination lines emitted by H
II regions.
Authors: Hoang-Binh, D.
1972saim.conf..367H Altcode:
No abstract at ADS
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Title: Stark broadening and radio recombination lines in NGC 7027.
Authors: Hoang-Binh, D.
1971A&A....10..159H Altcode:
The observed upper limit for the ratio T /T0 of central H 109cc line to
continuum brightness temperatures in NGC 7027 (Terzian and Balick, 1969)
is shown to be consistent with an electron density Ne> 10 cm-8. The
lower limit of 10 cm-8 for Ne is smaller by a factor 10 than that found
by Goldberg (1970), who did not consider Stark broadening. Further,
an emission measure considerably larger than the value derived by
high frequency flux measurements is not found necessary to account
for the upper limit for TL/To. Key words: Stark broadening - radio
recombination lines - H II regions
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Title: On the Interpretation of Radio Recombination Lines Emitted
by Galactic Nebulae
Authors: Hoang-Binh, D.
1970ApL.....6..151H Altcode:
No abstract at ADS
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Title: Influence of Dielectronic Recombination on the Radio
Recombination Lines of Carbon
Authors: Gayet, R.; Hoang Binh, D.; Joly, F.; McCarroll, R.
1969A&A.....1..365G Altcode:
The influence of dielectronic recombination on the population of the
highly excited states of carbon is examined under typical nebular
conditions. The resuits indicate that in certain circumstances,
dielectronic recombination can produce a considerable enhancement of
the recombination lines. Thus, for example, in an H II region with
an electron temperature 12000 K and electron density 50 cm-8, the C
109 line could appear in emission with an intensity of several per
cent of that of the neighbouring H 109 o' line. However, there is not
as yet sufficient information to permit the positive identification
of the anomalous microwave line in NGC 2024 and IC 1795 as a carbon
recombination line originating from an H II region.
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Title: Enhancement of the stimulated emission of radio-frequency
lines of hydrogen
Authors: Mac Caroll, R.; Hoang Binh, D.
1968AnAp...31..123M Altcode:
No abstract at ADS
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Title: Radio Recombination Lines: Populations of Highly Excited
States of Hydrogen
Authors: Hoang-Binh, D.
1968ApL.....2..231H Altcode:
No abstract at ADS
