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Author name code: querfeld
ADS astronomy entries on 2022-09-14
author:Querfeld, Charles William
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Title: Interpretation of polarization measurements of coronal Fe XIII
(10747 Å) emission.
Authors: Smartt, R. N.; Querfeld, C. W.
1991sopo.work..326S Altcode:
Measurements of the linear polarization of Fe XIII (10747 Å) coronal
emission are discussed. Polarization maps appear to be consistent with
the general form of the expected magnetic field distribution in the
corona as projected in the plane of the sky. Well-defined, large-scale
coronal structures are found to be mapped well by corresponding
polarization measurements.
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Title: Vector Magnetic Fields in Prominences - Part Two Hei d3 Stokes
Profiles Analysis for Two Quiescent Prominences
Authors: Querfeld, C. W.; Smartt, R. N.; Bommier, V.; Landi
Degl'Innocenti, E.; House, L. L.
1985SoPh...96..277Q Altcode:
The Stokes components of He I D<SUB>3</SUB> emission in two quiescent
prominences, using full spectral profile measurements, are analyzed to
derive vector magnetic fields. Two independently developed schemes,
based on the Hanle effect, are used for interpretation. They involve
solutions of the statistical equilibrium equations for the He I
D<SUB>3</SUB> multiplet, including the effect of coherency and full
level crossing, which predict the magnetic field dependence of the
observed polarization. Derived magnetic field vector solutions for
each pair of linear polarization Stokes profiles corresponding to
an observational point in the prominence are, intrinsically, not
uniquely determined, and a set of possible solutions is usually
obtained. However, mutual consistency of these solutions with
those independently predicted by the form of the circular polarized
component, allow, in almost all cases, rejection of all solutions of a
set except one symmetrical pair. Of such a pair, a unique solution can
be determined with a high confidence level by reference to independent
potential field information. Field vectors are found usually to be
close to horizontal and normal to the prominence surface, but extreme
exceptions are found. Field values range from 6 G to 60 G. The derived
vectorfield configurations and their magnitudes are briefly discussed
relative to these prominences and to different quiescent prominence
models.
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Title: Comparison of Coronal Emission Line Structure and Polarization
Authors: Querfeld, C. W.; Smartt, R. N.
1984SoPh...91..299Q Altcode:
Simultaneous observations obtained with the HAO/SPO coronal
emission-line polarimeter and the new SPO emission-line coronagraph
are compared. The polarimeter data are measured in the FeXIII (10747
Å) line and the coronagraph observations are recorded in the FeXIV
(5303 Å) line. The polarimeter field-of-view is relatively coarse
compared with the resolution limit of the coronagraph. Therefore,
the observed coronal polarization cannot be related directly to the
detailed loop structures that characterize the localized coronal
distribution, but it is found that large-scale emission features
have corresponding polarization signatures. Since the measured
linear polarization vectors describe the projected magnetic field
direction, as shown theoretically, it follows that the form of the
large-scale coronal distribution describes corresponding magnetic
field structures. Measured polarization values are consistent with
those predicted theoretically. Interpretation of these data to obtain
corresponding magnetic field directions suggests that the value usually
accepted for iron abundance in the corona might be too large.
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Title: Vector Magnetic Fields in Prominences - Part Three - Hei d3
Stokes Profile Analysis for Quiescent and Eruptive Prominences
Authors: Athay, R. G.; Querfeld, C. W.; Smartt, R. N.; Landi
Degl'Innocenti, E.; Bommier, V.
1983SoPh...89....3A Altcode:
Observations of linear polarization in two resolved components of HeI
D<SUB>3</SUB> are interpreted using the Hanle effect to determine vector
magnetic fields in thirteen prominences. As in all vector magnetic
field measurements, there is a two-fold ambiguity in field direction
that is symmetric to a 180° rotation about the line-of-sight. The
polar angles of the fields show a pronounced preference to be close to
90° from the local solar radius, i.e., the field direction is close
to horizontal. Azimuth angles show internal consistency from point to
point in a given prominences, but because of the rotational symmetry,
the fields may be interpreted, in most cases, as crossing the prominence
either in the same sense as the underlying photospheric fields or in
the opposite sense.
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Title: The formation and interpretation of the Fe XIII 10747 A
coronal emission line
Authors: Querfeld, C. W.
1982ApJ...255..764Q Altcode:
The intensity and linear polarization of the Fe XIII 10747 A coronal
emission line depends on the magnetic field direction, electron
density, temperature, and height of emitting coronal volumes. The
interpretation of coronal emission-line observations requires that
the effects of these variables on the coronal emission-line Stokes
vector be simply described. The Sahal-Brechot and House solutions of
statistical equilibrium equations for Fe XIII include fully the effects
of electron and proton collisions in the ground term and of electron
collisional excitation of excited terms which decay radiatively to
the ground term. The solutions are recast in a simple analytic form
which displays the explicit dependence of coronal line emission on
the relevant coronal conditions. A brief discussion of a zeroth order,
plane-of-the-sky interpretation algorithm is included.
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Title: Coronal emission-line polarization from the statistical
equilibrium of magnetic sublevels. II - Fe XIV 5303 A
Authors: House, L. L.; Querfeld, C. W.; Rees, D. E.
1982ApJ...255..753H Altcode:
Coronal magnetic fields influence the intensity and linear polarization
of light scattered by coronal Fe XIV ions. To interpret polarization
measurements of Fe XIV 5303 A coronal emission requires a detailed
understanding of the dependence of the emitted Stokes vector on
coronal magnetic field direction, electron density, and temperature
and on height of origin. The required dependence is included in the
solutions of statistical equilibrium for the ion which are solved
explicitly for 34 magnetic sublevels in both the ground and four
excited terms. The full solutions are reduced to equivalent simple
analytic forms which clearly show the required dependence on coronal
conditions. The analytic forms of the reduced solutions are suitable
for routine analysis of 5303 green line polarimetric data obtained at
Pic du Midi and from the Solar Maximum Mission Coronagraph/Polarimeter.
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Title: Narrow-band GaAsSb heterojunction detectors for coronal
polarimetry.
Authors: Querfeld, C. W.
1982AASPB..29....3Q Altcode:
No abstract at ADS
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Title: Stokes II — A new polarimeter for solar observations
Authors: Baur, T. G.; Elmore, D. E.; Lee, R. H.; Querfeld, C. W.;
Rogers, S. R.
1981SoPh...70..395B Altcode:
A Stokes polarimeter has been built at the High Altitude Observatory
to obtain line profiles in both linear and circular polarization in
solar spectral lines. These measurements are interpreted using the
theory of radiative transfer in the presence of a magnetic field to
obtain vector magnetic fields on the solar disk and using the theory
of resonance scattering and the Hanle effect to obtain vector magnetic
fields in prominences. The polarimeter operates on the Sacramento
Peak Observatory 40 cm coronagraph. It is an extensively modified and
improved version of an earlier instrument.
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Title: Measurements of Magnetic Fields in the Solar Atmosphere
Authors: Querfeld, C. W.
1981BAAS...13..560Q Altcode:
No abstract at ADS
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Title: Quiescent Prominence Vector Magnetic Fields Inferred from He
I D<SUB>3</SUB> Polarization
Authors: Querfeld, C. W.; Smartt, R. N.; Bommier, V.; Landi
Degl'Innocenti, E.
1980BAAS...12..792Q Altcode:
No abstract at ADS
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Title: Vector Magnetic Fields Inferred from He I D<SUB>3</SUB>
Polarization in the August 5, 1980 Eruptive Prominence
Authors: Querfeld, C. W.; Smartt, R. N.; Bommier, V.; Landi
Degl'Innocenti, E.
1980BAAS...12..913Q Altcode:
No abstract at ADS
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Title: Comparison of Coronal Emission-Line Structure and Observed
Polarization
Authors: Smartt, R. N.; Querfeld, C. W.
1980BAAS...12..793S Altcode:
No abstract at ADS
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Title: A Three-Coronagraph Record from 1 to 10 R<SUB>O</SUB> of the
Energetics of a Coronal Transient
Authors: Wagner, W. J.; Sawyer, C.; Illing, R. M. E.; House, L. L.;
Querfeld, C. W.; Sheeley, N. R., Jr.; Howard, R. A.; Koomen, M. J.;
Michels, D. J.; Smartt, R. N.
1980BAAS...12Q.902W Altcode:
No abstract at ADS
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Title: Experimental Search for Coronal Alfven Waves.
Authors: Querfeld, C. W.; Hollweg, J. V.
1978BAAS...10..431Q Altcode:
No abstract at ADS
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Title: A near-infrared coronal emission-line polarimeter.
Authors: Querfeld, C. W.
1977oppo.conf..200Q Altcode:
No abstract at ADS
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Title: Observations of Fe XIII 10747 coronal emission-line
polarization.
Authors: Querfeld, C. W.
1977ROLun..12..109Q Altcode:
No abstract at ADS
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Title: A near-infrared coronal emission-line polarimeter
Authors: Querfeld, C. W.
1977SPIE..112..200Q Altcode:
The direction, but not the magnitude, of the solar coronal magnetic
field is encoded in the linear polarization of certain coronal
emission lines. The High Altitude Observatory, in collaboration
with the Sacramento Peak Observatory, has constructed a polarimeter
which measures the plane polarization of the 10747 A and 10798
A Fe XIII emission lines. The instrument simultaneously provides
similar measurements of the continuum corona and the sky at 10690 A
to give the net emission line intensity and polarization. Polarization
brightness maps made with the 10747 A line clearly show the large-scale
organization of the coronal magnetic field and signatures characteristic
of diverging fields over sunspots, horizontal fields above filament
channels, and the Van Vleck turnover in helmet streamers.
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Title: Observation of Polarization in FeXIII 10747 Å Coronal
Emission Line
Authors: Querfeld, C. W.; Elmore, D. E.
1976BAAS....8..368Q Altcode:
No abstract at ADS
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Title: The High Altitude Observatory Coronal-Emmission Polarimeter
Authors: Querfeld, C. W.
1974psns.coll..254Q Altcode: 1974IAUCo..23..254Q; 1974psns.conf..254Q
No abstract at ADS
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Title: Observations of Far Infrared Atmospheric Windows at 44
cm<SUP>-1</SUP> and 50 cm<SUP>-1</SUP> from Pikes Peak
Authors: Mankin, W. G.; Eddy, J. A.; MacQueen, R. M.; Lee, R. H.;
Querfeld, C. W.
1973NPhS..245....8M Altcode: 1973Natur.245....8M
ABSORPTION by atmospheric water vapour seriously restricts astronomical
observations from the ground in the far infrared region of the
spectrum. Between 300 cm<SUP>-1</SUP> and 18 cm<SUP>-1</SUP>, the
atmosphere is nearly opaque from the ground, except from high mountain
sites where weak windows appear at 29 and 22 cm<SUP>-1</SUP> (350 and
450 µm). These windows were first observed by Gebbie<SUP>1</SUP>;
they have since been used by several investigators for mountain top
astronomical measurements<SUP>2-10</SUP>. To our knowledge, there
have been no astronomical observations from the ground in the region
between 300 cm<SUP>-1</SUP> and the 29 cm<SUP>-1</SUP> window. In this
frequency decade of the electromagnetic spectrum astronomy has required
the use of aircraft<SUP>11-16</SUP> and balloons<SUP>17-24</SUP>
as observing platforms.
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Title: Infrared atmospheric measurements on the Pikes Peak summit.
Authors: Querfeld, C. W.; Eddy, J. A.; Lee, R. H.; Mankin, W. G.
1973JOSA...63..476Q Altcode:
No abstract at ADS
