J/ApJ/924/43 Small-scale magnetic flux ropes from PSP (Chen+, 2022)
Small-scale magnetic flux ropes and their properties based on in situ
measurements from the Parker Solar Probe.
Chen Yu, Hu Q.
<Astrophys. J., 924, 43 (2022)>
=2022ApJ...924...43C 2022ApJ...924...43C
ADC_Keywords: Sun; Magnetic fields
Keywords: Astronomy data analysis ; Interplanetary turbulence ;
Solar magnetic reconnection ; Solar magnetic fields ; Solar wind
Abstract:
We report small-scale magnetic flux ropes via the in situ measurements
from the Parker Solar Probe during the first six encounters, and
present additional analyses to supplement our prior work in
Chen+ (2021ApJ...914..108C 2021ApJ...914..108C). These flux ropes are detected by the
Grad-Shafranov-based algorithm, with their durations and scale sizes
ranging from 10s to ≲1hr and from a few hundred kilometers to
10-3au, respectively. They include both static structures and those
with significant field-aligned plasma flows. Most structures tend to
possess large cross helicity, while the residual energy is distributed
over wide ranges. We find that these dynamic flux ropes mostly
propagate in the antisunward direction relative to the background
solar wind, with no preferential signs of magnetic helicity. The
magnetic flux function follows a power law and is proportional to
scale size. We also present case studies showing reconstructed
two-dimensional (2D) configurations, which confirm that both the
static and dynamic flux ropes have a common configuration of spiral
magnetic field lines (also streamlines). Moreover, the existence of
such events hints at interchange reconnection as a possible mechanism
for generating flux rope-like structures near the Sun. Lastly, we
summarize the major findings, and discuss the possible correlation
between these flux rope-like structures and turbulence due to the
process of local Alfvenic alignment.
Description:
The extended Grad-Shafranov-based algorithm is applied to time periods
around the first six Parker Solar Probe (PSP) perihelia, when
high-cadence data are available. The time periods for detection range
from 2018 October 31 to November 12, 2019 March 30 to April 11,
2019 August 23 to 31, 2020 January 23 to February 8, 2020 May 29 to
June 14, and 2020 September 18 to October 1, for encounters E1-E6,
respectively. The new detection is implemented for a total detection
period of over two months.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 148 5841 List of small-scale magnetic flux ropes (SFRs) and
associated properties during the first six
Parker Solar Probe (PSP) encounters
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See also:
J/ApJ/737/L35 : Pulsed Alfven waves in the solar wind (Gosling+, 2011)
J/ApJS/230/21 : Solar wind 3D magnetohydrodynamic simulation (Chhiber+, 2017)
J/ApJS/239/12 : Small-scale magnetic flux ropes in the solar wind (Hu+, 2018)
J/ApJ/871/93 : Solar wind speed from 5yr data with ACE (Wang+, 2019)
J/A+A/635/A79 : Pitch-angle distributions of solar wind (Carcaboso+, 2020)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/5841] Event index number
6- 15 A10 "M/D/Y" St.date Event start date (UT)
17- 24 A8 "h:m:s" St.time Event start time (UT)
26- 35 A10 "M/D/Y" End.date Event end date (UT)
37- 44 A8 "h:m:s" End.time Event end time (UT)
46- 49 I4 s Dur [10/3697] Event duration
51- 57 F7.3 nT Bavg [25/151] Average magnetic field strength
59- 63 F5.3 --- Betap [0.024/6.24] Average proton beta
65- 71 F7.3 km/s VSW [187.28/668.42] Average solar wind speed
73- 75 I3 deg theta [0/180] Polar angle
77- 79 I3 deg phi [0/360]? Azimuthal angle
81- 86 F6.3 --- zaxis0 [-0.985/0.985] Flux rope z-axis 0 component (1)
88- 93 F6.3 --- zaxis1 [-0.97/0.97] Flux rope z-axis 1 component (1)
95- 100 F6.3 --- zaxis2 [-1/1] Flux rope z-axis 2 component (1)
102- 108 F7.3 10-5AU Size [0.39/596] Flux rope scale size
110- 115 F6.3 --- WTS [-0.99/1.24] Walen test slope
117- 121 F5.3 --- MAavg [0.029/0.9] Average Alfvenic Mach number
123- 127 F5.3 AU RD [0.12/0.35] Heliocentric distance where event
identified
129- 134 F6.3 --- CH [-0.985/0.992] Density of normalized cross
helicity; σc
136- 141 F6.3 --- RE [-0.998/-0.1] Density of normalized residual
energy; σr
143- 148 F6.3 T.m Am [-1.85/10.4] Extreme value of magnetic flux
function
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Note (1): in RTN coordinates.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Aug-2023