J/A+A/647/A60 Prominence average magnetic fields in cycle XXI (Bommier+, 2021)
24 synoptic maps of average magnetic field in 296 prominences measured by the
Hanle effect during the ascending phase of solar cycle 21.
Bommier V., Leroy J.L., Sahal-Brechot S.
<Astron. Astrophys. 647, A60 (2021)>
=2021A&A...647A..60B 2021A&A...647A..60B (SIMBAD/NED BibCode)
ADC_Keywords: Sun ; Magnetic fields ; Polarization
Keywords: magnetic fields - polarization - Sun: magnetic fields -
sun: filaments, prominences
Abstract:
The aim of the present paper is to publish 24 synoptic maps of solar
filaments, in which 296 prominence average unambiguous magnetic field
vectors were determined by Pic-du-Midi observations between 1974 and
1982, which is the ascending phase of cycle XXI.
The magnetic field was determined by interpretation of the Hanle
effect observed in the HeI D3 line. Previou the prominence field
polarity and prominence chirality were applied to solve the
fundamental ambiguity. The meas averaged in each prominence for
accuracy reasons.
The result is twofold. First, alternating field directions can be
observed from one neutral line to the next general field alignment is
found along a solar North-South field distorted under the differential
rotation effect. The about prominence and their magnetic field
coordinates are provided as on-line material associated to this paper.
Description:
From our full sample of 3297 measurements achieved in 379
quiescent prominences observed in HeI D3 at the Pic-du-Midi during
the ascending phase of Cycle XXI (1974-1982), we discarded those
prominences for which the identification of the neutral line is
doubtful (64 prominences).
As a result, we obtained unambiguous average horizontal magnetic field
vectors of 296 prominences each associated to a filament observed
eight days before (W limb) or after (E limb).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
data.dat 96 296 296 prominences solar coordinates and
magnetic field vector data
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Byte-by-byte Description of file: data.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Type Type of prominence (1)
8- 12 A5 "h:m" UT time of observation (universal time)
14- 23 A10 "date" Obs.date Date of observation
24- 25 I2 deg b0 Disk center latitude
27- 29 I3 deg Lc Central meridian Carrington longitude
31- 33 I3 deg AP position angle of the observed prominence
with respect to the solar North,
anticlockwise)
35- 37 I3 deg b Prominence latitude
39- 41 I3 deg l Prominence longitude
43- 46 I4 --- Carr Carrington rotation reference number
48- 51 I4 deg Csi Angle between the filament and the parallel
(sign convention: Leroy et al.,
1984A&A...131...33L 1984A&A...131...33L, Fig. 4)
53- 55 I3 deg Chi Angle outside the sky plane
57- 60 I4 deg Los Angle between the line-of-sight and the
parallel (in degrees)
62- 65 F4.1 gauss B Average magnetic field strength (in Gauss)
67- 70 F4.1 gauss e_B Uncertainty on the magnetic field strength as
a result of the photometric accuracy
(in Gauss)
72- 75 I4 deg T Average magnetic field azimuth angle with
the parallel
77- 78 I2 deg e_T Uncertainty on the magnetic field azimuth as
a result of the photometric accuracy
80- 83 I4 deg a Alpha angle between the field vector and the
filament axis (sign convention: Leroy et al.,
1984A&A...131...33L 1984A&A...131...33L, Fig. 4)
85- 86 I2 --- Nav Number of averaged measurement points
88- 96 A9 --- Method Ambiguity resolution method
(polarity or chirality)
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Note (1): Type as follows:
POLARC = Polar Crown prominence
LOWLAT = low latitude prominence
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Acknowledgements:
Veronique Bommier, V.Bommier(at)obspm.fr
(End) Patricia Vannier [CDS] 11-Jan-2021