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Author name code: bessey
ADS astronomy entries on 2022-09-14
author:"Bessey, Robert J."
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Title: Modelling forbidden line emission profiles from colliding
wind binaries
Authors: Ignace, R.; Bessey, R.; Price, C. S.
2009MNRAS.395..962I Altcode: 2009arXiv0902.0527I; 2009MNRAS.tmp..422I
This paper presents calculations for forbidden emission-line profile
shapes arising from colliding wind binaries. The main application
is for systems involving a Wolf-Rayet (WR) star and an OB star
companion. The WR wind is assumed to dominate the forbidden line
emission. The colliding wind interaction is treated as an Archimedean
spiral with an inner boundary. Under the assumptions of the model, the
major findings are as follows. (i) The redistribution of the WR wind as
a result of the wind collision is not flux conservative but typically
produces an excess of line emission; however, this excess is modest at
around the 10 per cent level. (ii) Deviations from a flat-toped profile
shape for a spherical wind are greatest for viewing inclinations that
are more nearly face-on to the orbital plane. At intermediate viewing
inclinations, profiles display only mild deviations from a flat-toped
shape. (iii) The profile shape can be used to constrain the colliding
wind bow shock opening angle. (iv) Structure in the line profile tends
to be suppressed in binaries of shorter periods. (v) Obtaining data
for multiple forbidden lines is important since different lines probe
different characteristic radial scales. Our models are discussed in
relation to Infrared Space Observatory data for WR 147 and γ Vel
(WR 11). The lines for WR 147 are probably not accurate enough to
draw firm conclusions. For γ Vel, individual line morphologies are
broadly reproducible but not simultaneously so for the claimed wind
and orbital parameters. Overall, the effort demonstrates how lines
that are sensitive to the large-scale wind can help to deduce binary
system properties and provide new tests of numerical simulations.
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Title: Coronal Temperature Measurements Near a Helmet Structure Base
at the 1973 Solar Eclipse
Authors: Bessey, R. J.; Liebenberg, D. H.
1984SoPh...94..239B Altcode:
Observations of coronal Fe XIV emission lines from the NE quadrant
during the 1973 solar eclipse are reported. Temperatures are deduced
from a pure thermal broadening model, and, in the region near an
observed white-light enhancement, an alternative interpretation of
halfwidth as being in part due to turbulent velocities is suggested.
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Title: The Formation of Prominences by Thermal Instability - a
Numerical Study
Authors: Mason, S. F.; Bessey, R. J.
1983SoPh...83..121M Altcode:
A two-dimensional model of prominence formation in a region
containing a magnetic neutral sheet is constructed for a variety
of initial conditions, assuming the coronal plasma to be described
by the usual hydromagnetic approximation, with infinite electric
conductivity. In each case the magnetic field is initially vertical,
varying antisymmetrically with respect to the neutral sheet, to a
maximum value at a distance of 70 000 km from the neutral sheet. In
the first case, the plasma is initially in hydrostatic equilibrium,
whereas in successive cases, the pressure is assumed to be of such
a value that the plasma is in lateral equilibrium of total pressure
(gas plus magnetic). In a variation of this case, the value of the
solar gravitational field was artificially reduced, and the effects
considered.
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Title: Coronal Emission Line Profiles with Five Arc Second Spatial
Resolution
Authors: Bessey, R.; Liebenberg, D. H.
1980BAAS...12..916B Altcode:
No abstract at ADS
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Title: Evidence for temporal variations of coronal emission line
intensity and profile.
Authors: Liebenberg, D. H.; Bessey, R. J.; Watson, B.
1976SoPh...50..109L Altcode:
The time sequence of line profiles of Fe XIV emission obtained at the
1965 solar eclipse is examined for temporal variations of intensity and
profile. Although no variations are found in some regions examined,
two regions with intensity and profile line width variations are
found. A simple temperature wave is consistent with observations.
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Title: A time evolution study of limb spicule spectra.
Authors: Krall, K. R.; Bessey, R. J.; Beckers, J. M.
1976SoPh...46...93K Altcode:
Time sequences of simultaneous spectra of limb spicules, obtained
using the Sacramento Peak Observatory's tower telescope and echelle
spectrograph are analyzed. Intensity determinations of Hα and K, H,
λ 8498 and λ 8542 of calcium are tabulated for three observing
heights. Electron densities averaged over the entire visible
lifetimes of spicules are ∼-6 × 10<SUP>10</SUP> cm<SUP>−3</SUP>
at observing heights of 6000km, while maximum and minimum values were
∼-1.1 × 10<SUP>11</SUP> cm<SUP>−3</SUP> at 6000km and ∼- 2 ×
10<SUP>10</SUP> cm<SUP>−3</SUP> at 10000km. Electron temperatures
range between 12 000 K and 16 000 K. Profile halfwidths indicate
turbulent velocities of 12 to 22 km s<SUP>−1</SUP>, and spectral
tilts are interpreted as caused by differential velocity fields of ∼-3
km s<SUP>−1</SUP> per 1000 km. No large scale spicule expansions or
contractions are observed, although possible expulsions or accretions
of material are observed. Spicules may be wider in the calcium K and
H lines than in Hα.
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Title: Coronal Emission Line Profile Observations at Total Solar
Eclipses. II: 30 May 1965 Results, Deconvolution and Interpretation
Authors: Liebenberg, D. H.; Bessey, R. J.; Watson, B.
1975SoPh...44..345L Altcode:
High resolution spectra of the coronal emission line Fe XIV at 530.3
nm obtained at the 30 May 1965 total solar eclipse are analyzed and
interpreted. Deconvolution techniques that preserve the line intensity
vs wavelength profile shape are developed to obtain further resolution
improvement. The west limb coronal enhancement is determined to have
temperatures less than 3 MK and turbulent velocities of ∼25 km
s<SUP>-1</SUP> decreasing with altitude. Temperature gradients provide
evidence for marginal solar wind flow from this enhancement. Above the
quiet photosphere in the southwest quadrant the comparison of line and
continuum intensities and consideration of line width suggest to us
the coronal region is filled with inhomogeneous plasma, dense enough
in localized regions to maintain collisional excitation. Solar wind
flow from this region obtains when turbulent velocities are assumed
to contribute to the line broadening. We identify this region as a
coronal hole and suggest that coronal material is heated by the quiet
photosphere below.
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Title: On the Spicular Density Enhancement in the Region of Formation
Authors: Sahai, S. K.; Bessey, R. J.
1975SoPh...42...67S Altcode:
The possibility is examined of setting an upper limit to the density
enhancement of solar spicules relative to their formation region. The
total conductive energy per sec available in a spicular region is
determined analytically together with the total energy radiated per
sec and the maximum density enhancement in the same region. The results
indicate that spicules cannot cover more than 8% of the surface in their
formation region and that at least 13% of the downward conductive flux
must be directed from interspicular regions to rosette centers.
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Title: Solar Wind Development in the Middle Corona
Authors: Liebenberg, D. H.; Bessey, R.; Watson, B.
1975BAAS....7..358L Altcode:
No abstract at ADS
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Title: Observed coronal temperatures at 1.37R <SUB>⊙</SUB> in the
region of a helmet structure
Authors: Liebenberg, D. H.; Bessey, R. J.; Watson, B.
1975SoPh...40..387L Altcode:
During the total solar eclipse, 1965 May 30, a 25 cm aperturef/8.0
telescope and Fabry-Perot interferometer were operated aboard the
USAF-AEC aircraft. High resolution spectra of the FeXIV emission line,
530.3 nm, were obtained. Deconvolved intensity vs wavelength profiles
of the second order fringe overlay a helmet structure on the NM limb at
out to 1.37R<SUB>⊙</SUB>. The profiles yield coronal temperatures,
absolute intensities and Doppler velocities in regions of apparently
open magnetic field structure and within the closed field lines of
the helmet. Together with white light intensities the observations
are interpreted to provide temperatures and turbulent velocities in
and around this coronal structure. Comparison is made with a model by
Billings and Roberts. We suggest a model with radial flow (solar wind)
velocities of ∼ 60 km s<SUP>−1</SUP> satisfies the observations
in the open field line region.
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Title: A Dynamical Model of the Corona
Authors: Browne, Stephen L.; Bessey, Robert J.
1973SoPh...31..351B Altcode:
The hydrodynamic equations for an ideal, inviscid, fully ionized
hydrogen gas in a gravitational, but not magnetic, field are solved by
an explicit Lax-Wendroff two-step technique using a one-dimensional
slab symmetry. Radiation and thermal conductivity are included. The
model spans 100000 km starting from the chromosphere-corona transition
region. An initially isothermal gas is seen to evolve coronal
properties in 4000 s, by which time it settles into dynamic equilibrium
characterized by a 2000 km transition region, a temperature maximum
of 1.6 × 10<SUP>6</SUP> K at a height of 60000 km, and a solar wind
mass flux of 10<SUP>-9</SUP> g cm<SUP>-2</SUP> s<SUP>-1</SUP>.
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Title: Coronal Emission Line Profile Analysis from Airborne Eclipse
Observations of 30 May 1965.*
Authors: Liebenberg, D. H.; Bessey, R.; Watson, B.
1973BAAS....5S.275L Altcode:
No abstract at ADS
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Title: Thermally Driven Motions in a Gravitational Atmosphere
Authors: Bessey, R. J.; Kuperus, M.
1970SoPh...12..216B Altcode:
Numerical solutions of the non-linear equations of fluid dynamics for a
compressible inviscid initially isothermal atmosphere are given using
Lax' method for the integration of the equations when discontinuities
occur in the flow. The motion of the atmosphere is studied following
the heating of a thin layer in the atmosphere. It is found that
for a sufficiently large heat input the atmosphere strongly expands
towards the regions of lower densities. In most cases a shock wave is
formed which precedes the expanding region. The possible occurrence
of thermally generated motions in the solar chromosphere is discussed.
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Title: Thermally Driven Motions in a Gravitational Atmosphere
Authors: Bessey, R. J.; Kuperus, M.
1969cctr.conf..191B Altcode:
No abstract at ADS
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Title: Doppler Shifts and Line Broadening in Spicules.
Authors: Athay, R. Grant; Bessey, R. J.
1964ApJ...140.1174A Altcode:
Doppler shifts measured for solar spicuies in Ha, D3, and H (Ca ii)
suggest that the anomalously broad lines of Ca ii (Athay 1961) are due,
in part, to inadequate spatial resolution as suggested by Zirker (1962),
but that this is not the primary cause of the anomalous broadening. Ha
and H and K spicules are found to have predominantly wide profiles at
low and intermediate heights, but at great heights the profile widths
for most of the few remaining features are only about one-third as
wide as at lower heights. It appears that this results mainly, however,
from the fact that the features with narrow profiles are intrinsically
brighter at great heights than are the features with wide profiles
It does not appear to result from strong systematic decrease of line
width with height for individual spicules. Only a small percentage of
the features with wide profiles resolves into clusters of spicules
with narrow profiles at great heights. Doppler velocities are found
to be less than 12 km/sec for about two-thirds of equatorial spicules
with the remaining one-third showing Doppler velocities up to about 30
km/sec. Almost all polar spicules have Doppler velocities less than 12
km/sec. No other significant differences between polar and equatorial
spicules were found.
