Author name code: querfeld ADS astronomy entries on 2022-09-14 author:Querfeld, Charles William ------------------------------------------------------------------------ Title: Interpretation of polarization measurements of coronal Fe XIII (10747 Å) emission. Authors: Smartt, R. N.; Querfeld, C. W. Bibcode: 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. 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. Bibcode: 1985SoPh...96..277Q Altcode: The Stokes components of He I D3 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 D3 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. Title: Comparison of Coronal Emission Line Structure and Polarization Authors: Querfeld, C. W.; Smartt, R. N. Bibcode: 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. 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. Bibcode: 1983SoPh...89....3A Altcode: Observations of linear polarization in two resolved components of HeI D3 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. Title: The formation and interpretation of the Fe XIII 10747 A coronal emission line Authors: Querfeld, C. W. Bibcode: 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. 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. Bibcode: 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. Title: Narrow-band GaAsSb heterojunction detectors for coronal polarimetry. Authors: Querfeld, C. W. Bibcode: 1982AASPB..29....3Q Altcode: No abstract at ADS 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. Bibcode: 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. Title: Measurements of Magnetic Fields in the Solar Atmosphere Authors: Querfeld, C. W. Bibcode: 1981BAAS...13..560Q Altcode: No abstract at ADS Title: Quiescent Prominence Vector Magnetic Fields Inferred from He I D3 Polarization Authors: Querfeld, C. W.; Smartt, R. N.; Bommier, V.; Landi Degl'Innocenti, E. Bibcode: 1980BAAS...12..792Q Altcode: No abstract at ADS Title: Vector Magnetic Fields Inferred from He I D3 Polarization in the August 5, 1980 Eruptive Prominence Authors: Querfeld, C. W.; Smartt, R. N.; Bommier, V.; Landi Degl'Innocenti, E. Bibcode: 1980BAAS...12..913Q Altcode: No abstract at ADS Title: Comparison of Coronal Emission-Line Structure and Observed Polarization Authors: Smartt, R. N.; Querfeld, C. W. Bibcode: 1980BAAS...12..793S Altcode: No abstract at ADS Title: A Three-Coronagraph Record from 1 to 10 RO 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. Bibcode: 1980BAAS...12Q.902W Altcode: No abstract at ADS Title: Experimental Search for Coronal Alfven Waves. Authors: Querfeld, C. W.; Hollweg, J. V. Bibcode: 1978BAAS...10..431Q Altcode: No abstract at ADS Title: A near-infrared coronal emission-line polarimeter. Authors: Querfeld, C. W. Bibcode: 1977oppo.conf..200Q Altcode: No abstract at ADS Title: Observations of Fe XIII 10747 coronal emission-line polarization. Authors: Querfeld, C. W. Bibcode: 1977ROLun..12..109Q Altcode: No abstract at ADS Title: A near-infrared coronal emission-line polarimeter Authors: Querfeld, C. W. Bibcode: 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. Title: Observation of Polarization in FeXIII 10747 Å Coronal Emission Line Authors: Querfeld, C. W.; Elmore, D. E. Bibcode: 1976BAAS....8..368Q Altcode: No abstract at ADS Title: The High Altitude Observatory Coronal-Emmission Polarimeter Authors: Querfeld, C. W. Bibcode: 1974psns.coll..254Q Altcode: 1974IAUCo..23..254Q; 1974psns.conf..254Q No abstract at ADS Title: Observations of Far Infrared Atmospheric Windows at 44 cm-1 and 50 cm-1 from Pikes Peak Authors: Mankin, W. G.; Eddy, J. A.; MacQueen, R. M.; Lee, R. H.; Querfeld, C. W. Bibcode: 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-1 and 18 cm-1, the atmosphere is nearly opaque from the ground, except from high mountain sites where weak windows appear at 29 and 22 cm-1 (350 and 450 µm). These windows were first observed by Gebbie1; they have since been used by several investigators for mountain top astronomical measurements2-10. To our knowledge, there have been no astronomical observations from the ground in the region between 300 cm-1 and the 29 cm-1 window. In this frequency decade of the electromagnetic spectrum astronomy has required the use of aircraft11-16 and balloons17-24 as observing platforms. Title: Infrared atmospheric measurements on the Pikes Peak summit. Authors: Querfeld, C. W.; Eddy, J. A.; Lee, R. H.; Mankin, W. G. Bibcode: 1973JOSA...63..476Q Altcode: No abstract at ADS