Author name code: neven
ADS astronomy entries on 2022-09-14
author:Neven, Luc
------------------------------------------------------------------------  

Title: Atlas photometrique du spectre solaire de [lambda] 3000 a
    [lambda] 10000
Authors: Delbouille, L.; Roland, G.; Neven, L.
Bibcode: 1990apds.book.....D
Altcode:
  No abstract at ADS

Title: Atlas photometrique du spectre solaire de [lambda] 3000 a
    [lambda] 10000. Vol.2
Authors: Delbouille, L.; Roland, G.; Neven, L.
Bibcode: 1989apds.book.....D
Altcode:
  No abstract at ADS

Title: The Photospheric Velocity Field of Procyon
Authors: de Jager, C.; Neven, L.
Bibcode: 1982Ap&SS..84..297D
Altcode:
  BUSS observations of the profiles of two well observed spectral lines
  in the ultraviolet spectrum of αCMi (Procyon; F5 IV V) are analysed
  with a Fourier transform method in order to determine values of various
  parameters of the velocity field of the upper photosphere. We find a
  microturbulent line-of-sight velocity componentL <SUB>μ</SUB> = 0.9 ±
  0.4 km s<SUP>-1</SUP>, a macroturbulent velocity componentL <SUB>M</SUB>
  = 5.3 ± 0.2 km s<SUP>-1</SUP>, and a rotational velocity componentv
  <SUB>R</SUB> sini=10.0±1.2 km s<SUP>-1</SUP>. In these calculations a
  single-moded sinusoidal isotropic macroturbulent velocity function was
  assumed. The result appears to be sensitive to the assumed shape of the
  macroturbulence function: for an assumed Gaussian shape the observations
  can be described withv <SUB>R</SUB> sini=4 km s<SUP>-1</SUP> andL
  <SUB>M</SUB> = 11.6 ± 2.7 km s<SUP>-1</SUP>. A comparison is made
  with other results and theoretical predictions.

Title: Stellar Atmospheric Velocity Fields - the Beta-Cephei Variables
    Gamma-Pegasi and Beta-Cephei
Authors: de Jager, C.; Sato, N.; Burger, M.; Neven, L.
Bibcode: 1982Ap&SS..83..411D
Altcode:
  The shape parameters of a number of selected ultraviolet lines in
  BUSS-spectra of the Beta Cephei stars γ Peg and β Cep have been
  analyzed to determine the principal parameters of the atmospheric
  velocity field. We find for both stars a fairly high value (∼5
  km s<SUP>-1</SUP>) for the microturbulent line-of-sight velocity
  component, which confirms an earlier result based on lower resolution
  UV spectra. Macroturbulent and rotational velocities are virtually zero
  in the atmosphere of γ Peg; for β Cep we findv <SUB>rot</SUB>sini=40
  km s<SUP>-1</SUP>.

Title: The ultraviolet spectrum of BET CMa stars.
Authors: Burger, M.; de Jager, C.; Kamperman, T. M.; Neven, L.
Bibcode: 1980A&A....90..170B
Altcode:
  Ultraviolet spectra of 15 beta Canis Majoris stars in wavelength bands
  of approximately 100 A around 2100, 2500, and 2800 A (resolution 1.8
  A), obtained with the Ultraviolet Stellar Spectrophotometer S 59 on
  board the ESRO TD-1A satellite are discussed. In general the spectra
  are similar to those of 'normal' stars, only the star alpha Vir has He
  I, C II, and Mg II lines slightly weaker than normal. Comparison with
  theoretical computations shows that the Fe abundance in the beta CMa
  stars is solar and that the average microturbulent velocity is about 4
  km/sec. The UV spectral lines of beta Cep do not show any significant
  variations in equivalent width with phase.

Title: Analysis of spectra of α CMi and α Cen A observed with
    the orbiting stellar ultraviolet spectrophotometer S59 in ESRO's
    TD1A satellite
Authors: de Jager, C.; Kamperman, T. M.; Neven, L.
Bibcode: 1978Ap&SS..54..343D
Altcode:
  Ultraviolet spectra of α CMi and α Cen A taken with moderate
  spectral resolution (approx. 1.8 Å) are used to analyse whether
  a determination of stellar chemical abundances of Fe and Cr and of
  the photospheric parameters is possible. For αCMi, for which good
  spectral data are available, we findT <SUB>eff</SUB>=7660±110 K;
  logg <SUB>eff</SUB>=3.05±0.1. Further, Δlogɛ(Fe)=-0.06±0.09; Δ log
  ɛ(Cr)=-0.01±0.09 with regard to ‘standard’ (solar) abundances. For
  α Cen A the resulting data — particularly the photospheric ones —
  are less certain, but it seems that the Fe abundance may be smaller
  than the ‘standard’ value.

Title: The Radiation Field in Photospheric Models for Extreme
    Supergiants
Authors: de Jager, C.; Neven, L.
Bibcode: 1975Ap&SS..33..295D
Altcode:
  On the basis of assumed photospheric temperature models for 36
  extreme supergiants (logg <SUB> e </SUB>-values of 1, 0.5 and 0;T
  <SUB> e </SUB>ranging from approx. 3700 33 000 K) photospheric
  fluxesS(τ<SUB>λ</SUB>) were computed for 36 wavelengths ranging
  from 100 Å to 60 000 Å. The hot models are in perfect radiative
  equilibrium; the cooler show deviations up to 10%, sometimes even
  larger. Only in the relatively deep parts of the photospheres
  (τ<SUB>5</SUB>≳1) the radiation field at each geometrical level
  can be characterized by one unique radiation temperature; for smaller
  τ<SUB>5</SUB>-values there are large deviations from local thermal
  equilibrium. The influence of deviations from local thermodynamical
  equilibrium on the fluxes is briefly examined, and appears small but
  for the shortest wavelengths. In tables and graphs we give for these
  models πF(γ)-values, integrated fluxes, effective temperatures,
  coloursU, B andV, and the Balmer discontinuityD.

Title: Atlas photometrique du spectre solaire de [lambda] 3000 a
    [lambda] 10000
Authors: Delbouille, L.; Roland, G.; Neven, L.
Bibcode: 1973apds.book.....D
Altcode: 1973QB551.D423.....
  No abstract at ADS

Title: The empirical determination of line source functions, β <SUB>
    L </SUB>-values, and the microturbulent and convective velocity
    components as functions of depth in the photosphere-chromosphere
    transition region
Authors: De Jager, C.; Neven, L.
Bibcode: 1972SoPh...25..277D
Altcode:
  An empirical method for determining line source functions, previously
  applied by us to the cores of infrared lines has now been extended to
  the whole line profile and was applied to centre-limb observations of
  sixteen lines of five infrared multiplets, mainly of high excitation
  potential (Table I). The present investigation was performed in two
  steps. In the first part of the paper approximate values are derived
  for the depth dependence of the four functions named in the title of
  this paper, where β<SUB>L</SUB> is the ratio between the actual and
  the LTE population of the lower level of the transitions involved. In
  the second part of the paper we use these empirically derived functions
  to compute the line profiles. From the remaining differences between
  observed and computed profiles, corrections are derived to the four
  functions. The main results are: (a) Convective velocities: see Table
  IV.(b)(Micro-)turbulent velocities: see Figure 8. Between τ<SUB>5</SUB>
  = 10<SUP>-4</SUP> and 10<SUP>-1</SUP>: «υ<SUB>τ</SUB>» ≈ 1.4 km
  s<SUP>-1</SUP>, which is an upper limit since an unknown contribution of
  macroscopic motions could not be separated, (c) Line source functions:
  see Figures 9, 15 and 16. The source functions are close to the
  black-body function for τ<SUB>5</SUB>≳ 10<SUP>-3</SUP>, slight
  deviations occur in higher levels. The interesting behaviour of the
  CaII source function near τ<SUB>5</SUB> = 10<SUP>-5</SUP> should be
  noted. (d) Non LTE-functions: first approximations for the functions
  log β<SUB>L</SUB> (τ<SUB>5</SUB>) were derived empirically in the
  first part, and are shown in Figure 10; the second approximation shows
  them to be too large and the real values seem to be closer to one-half
  or one-third of these functions.

Title: On the Applicability of Goldberg and Unno's Method to the
    Determination of Microturbulent Velocities in an Atmosphere with
    Convection
Authors: De Jager, C.; Neven, L.
Bibcode: 1972SoPh...22...49D
Altcode:
  The method of Goldberg and Unno for the determination of microturbulent
  velocities in a stellar atmosphere is only applicable if there are no
  macroturbulent or convective motions.

Title: Damping Constants for Infrared Fraunhofer Lines
Authors: De Jager, C.; Neven, L.
Bibcode: 1970SoPh...11....3D
Altcode:
  Empirical values of solar damping constants and their variation with
  optical depth were derived according to a method developed earlier by
  the authors. The damping constants refer to six infrared multiplets
  (24 lines). The average optical depths range from τ<SUB>0</SUB> =
  0.5 to 2.2. Corresponding theoretical damping constants were computed,
  mainly on the basis of Van der Waals damping, and with the help of
  detailed computations of the mean square radii of the atomic levels by
  Van Rensbergen. The empirical values are systematically larger than
  the theoretical ones, with factors ranging between 1.8 and 4.9. Some
  speculations about the source of this discrepancy are given.

Title: On the Occurrence of Convective Motions in the Upper
    Photosphere
Authors: De Jager, C.; Neven, L.
Bibcode: 1968SoPh....4..379D
Altcode:
  We have examined whether the motion field in the photosphere in the
  range of optical depths 0.25&lt; τ<SUB>0</SUB>&lt; 0.6 is dominated
  by thermal convection or by vibrations. The observed asymmetries
  of infrared Fraunhofer lines indicate the presence of motions, and
  the fact that the asymmetry is zero for lines of low excitation and
  increases with the excitation potential shows that these motions are
  chiefly convective in this part of the photosphere: upward moving
  elements appear to be hotter than downward moving ones.

Title: Source Functions in the Cores of Infrared Fraunhofer Lines
Authors: De Jager, C.; Neven, L.
Bibcode: 1968SoPh....3..159D
Altcode:
  No abstract at ADS

Title: Errata
Authors: de Jaher, C.; Neven, L.
Bibcode: 1968BANS....2..291D
Altcode:
  No abstract at ADS

Title: A Systematic Method for the Analysis of High-Resolution
    Fraunhofer Line Profiles
Authors: De Jager, C.; Neven, L.
Bibcode: 1967SoPh....1...27D
Altcode:
  A fraunhofer line profile depends on various parameters, partly
  related to the photospheric structure (T, P<SUB>g</SUB>, P<SUB>e</SUB>,
  v<SUB>conv</SUB>, v<SUB>turb</SUB>), partly to the atom or ion involved
  (such as oscillator strength, energy levels), partly also resulting
  from the interaction of the relevant kind of particles with the
  photosphere, and the photospheric radiation field. In this paper we
  shall mainly pay attention to the determination of: the macroturbulent
  (convective) velocities, v<SUB>conv</SUB> (τ); the damping constant
  γ (τ); the abundance, A<SUB>el</SUB>; the distribution function
  ϕ(v<SUB>conv</SUB>, τ) of the convective velocities at each depth
  τ; the source function, S (τ); the microturbulent velocities,
  v<SUB>turb</SUB> (τ).

Title: Observation of solar line profiles. I. The centre-to-limb
    variation of profiles of fifty lines in the near infrared solar
    spectrum
Authors: de Jager, C.; Neven, L.
Bibcode: 1967BANS....1..325D
Altcode: 1966BANS....1..325N; 1966BANS....1..325D
  No abstract at ADS

Title: Spectroscopic data for sixty new model photospheres
Authors: de Jager, C.; Neven, L.
Bibcode: 1967BANS....2..125D
Altcode:
  No abstract at ADS

Title: Observation of solar line profiles. I. The centre-to-limb
    variation of profiles of fifty lines in the near infrared solar
    spectrum (Abstract)
Authors: de Jager, C.; Neven, L.
Bibcode: 1967BAN....19..160D
Altcode:
  No abstract at ADS

Title: Spectroscopic data for sixty new model photospheres
Authors: de Jager, Cornelis; Neven, L.
Bibcode: 1967sdsn.book.....D
Altcode: 1967QB1.B94v2n4....
  No abstract at ADS

Title: Note on the influence of the apparatus profile on spectral
    line profiles
Authors: de Jager, C.; Neven, L.
Bibcode: 1966BAN....18..306D
Altcode:
  No abstract at ADS

Title: Deviations from LTE in the Catom and the Abundance of C in
    the Solar Photosphere
Authors: de Jager, C.; Neven, L.
Bibcode: 1966IAUS...26..149D
Altcode:
  No abstract at ADS

Title: The profile of the infrared He I lines over the undisturbed
    solar disk
Authors: de Jager, C.; Namba, O.; Neven, L.
Bibcode: 1966BAN....18..128D
Altcode:
  No abstract at ADS

Title: The Computation of Spectroscopic Data for 60 New Model
    Photopheres
Authors: de Jager, C.; Neven, L.
Bibcode: 1964SAOSR.167..270D
Altcode:
  No abstract at ADS

Title: The abundance of lead in the Sun
Authors: de Jager, C.; Neven, L.
Bibcode: 1962BAN....16..307D
Altcode:
  No abstract at ADS

Title: Tables and graphs enabling the computation of the profiles of H
    [gamma] and H [delta] in stellar spectra
Authors: de Jager, Cornelis; Neven, L.
Bibcode: 1962AnOB....9.....D
Altcode: 1962AnBel...9.....D
  No abstract at ADS

Title: The Ultra-Violet and X-Ray Spectra of the Stars
Authors: de Jager, C.; Neven, L.
Bibcode: 1961LIACo..10..552D
Altcode: 1961MSRSL...4..551D; 1961LIACo..10..551D
  No abstract at ADS

Title: Observations of infrared solar line profiles
Authors: Delbouille, L.; de Jager, C.; Neven, L.
Bibcode: 1960AnAp...23..949D
Altcode:
  No abstract at ADS

Title: The computation of partition functions in a stellar atmosphere
Authors: de Jager, C.; Neven, L.
Bibcode: 1960BAN....15...55D
Altcode:
  No abstract at ADS

Title: A program for the computation of b<SUB>n</SUB> tables for H
    and He
Authors: de Jager, C.; Kanno, M.; Neven, L.
Bibcode: 1960AnAp...23..843D
Altcode:
  No abstract at ADS

Title: Saturation effects in very faint Fraunhofer lines
Authors: de Jager, C.; Neven, L.
Bibcode: 1959Obs....79..102D
Altcode:
  No abstract at ADS

Title: 36. The Influence of the Metal Abundance on the Continuous
    Stellar Spectra
Authors: De Jager, C.; Neven, L.
Bibcode: 1959LIACo...9..413D
Altcode: 1959MSRSL...3..413D
  No abstract at ADS

Title: Spectroscopic data for 50 model photospherese
Authors: de Jager, Cornelis; Neven, L.
Bibcode: 1957sdfm.book.....D
Altcode: 1957QB4.U8l13p4....
  No abstract at ADS

Title: Spectroscopic data for 50 model photospheres
Authors: de Jager, Cornelis; Neven, L.
Bibcode: 1957AnOB....8.....D
Altcode: 1957AnBel...8.....D
  No abstract at ADS

Title: The Abundances of Diatomic Molecules of H, C, N, and O and
    of H2O in Stellar Atmospheres
Authors: de Jager, C.; Neven, L.
Bibcode: 1957LIACo...7..357D
Altcode:
  No abstract at ADS

Title: The profile of the Brackett α line in the solar spectrum
Authors: de Jager, C.; Migeotte, M.; Neven, L.
Bibcode: 1956AnAp...19....9D
Altcode:
  No abstract at ADS

Title: Observational models and helium abundances of the atmospheres
    of four B-type stars
Authors: Neven, L.; de Jager, C.
Bibcode: 1954BAN....12..103N
Altcode:
  No abstract at ADS

Title: La détermination de l'abondance relative de l'hélium dans
    les étoiles chaudes
Authors: Neven, L.
Bibcode: 1954LIACo...5..358N
Altcode: 1954MSRSL...1..358N; 1954pna..conf..358N
  No abstract at ADS

Title: High-Dispersion Solar Spectrograms Between 15μ and 24μ.
Authors: Migeotte, M.; Neven, L.
Bibcode: 1952ApJ...115..326M
Altcode:
  No abstract at ADS

Title: The interpretation of the observed hydrogen lines in the
    infrared solar spectrum II.
Authors: de Jager, C.; Neven, L.
Bibcode: 1952PRNAA..55..165D
Altcode: 1952RNAAS..55..165D
  No abstract at ADS

Title: Récents progrès dans l'observation du spectre infra-rouge
    du soleil a la station scientifique du Jungfraiijoch (Suisse)
Authors: Migeotte, M.; Neven, L.
Bibcode: 1952LIACo...3..165M
Altcode:
  No abstract at ADS

Title: The model of the solar atmosphere and the continuous absorption
    coefficient in the infrared
Authors: Neven, L.; de Jager, C.
Bibcode: 1951BAN....11..291N
Altcode:
  No abstract at ADS

Title: Nouvelles raies du méthane tellurique
Authors: Migeotte, Marcel; Neven, L.
Bibcode: 1951AnAp...14..315M
Altcode:
  No abstract at ADS

Title: The profiles of the lines of the Paschen and Brackett series
    of hydrogen in the solar spectrum.
Authors: de Jager, C.; Neven, L.
Bibcode: 1950PRNAA..53..157D
Altcode: 1950RNAAS..53..157D
  No abstract at ADS

Title: Mesures Micrometriques D'Etoiles Doubles
Authors: Neven, L.
Bibcode: 1949AnOB....4..201N
Altcode:
  No abstract at ADS

Title: Mesures micrometriques d'etoiles doubles
Authors: Neven, L.
Bibcode: 1948AnOB....4..201N
Altcode: 1948AnBel...4..201N
  No abstract at ADS

Title: Mesures micrometriques d'etoiles doubles
Authors: Neven, L.
Bibcode: 1948AnOB....4..277N
Altcode:
  No abstract at ADS

