J/ApJ/759/69 Solar electron events from 1995 to 2005 with WIND/3DP (Wang+, 2012)
A statistical study of solar electron events over one solar cycle.
Wang L., Lin R.P., Krucker S., Mason G.M.
<Astrophys. J., 759, 69 (2012)>
=2012ApJ...759...69W 2012ApJ...759...69W
ADC_Keywords: Sun ; Stars, flare
Keywords: Sun: coronal mass ejections, CMEs; Sun: flares;
Sun: particle emission; Sun: radio radiation
Abstract:
We survey the statistical properties of 1191 solar electron events
observed by the WIND 3DP instrument from <1keV to ≳300keV for a solar
cycle (1995 through 2005). After taking into account times of high
background, the corrected occurrence frequency of solar electron
events versus peak flux exhibits a power-law distribution over three
orders of magnitude with exponents between -1.0 and -1.6 for different
years, comparable to the frequency distribution of solar proton
events, microflares, and coronal mass ejections (CMEs), but
significantly flatter than that of soft X-ray (SXR) flares. At 40keV
(2.8keV), the integrated occurrence rate above ∼0.29
(∼330)/cm2/s.sr-1/keV near 1 AU is ∼1000/year (∼600/year) at solar
maximum and ∼35/year (∼25/year) at solar minimum, about an order of
magnitude larger than the observed occurrence rate. We find these
events typically extend over ∼45° in longitude, implying the
occurrence rate over the whole Sun is ∼104/year near solar maximum.
The observed solar electron events have a 98.75% association with type
III radio bursts, suggesting all type III bursts may be associated
with a solar electron event. They have a close (∼76%) association with
the presence of low-energy (∼0.02-2MeV/nucleon), 3He-rich
(3He/4He≥0.01) ion emissions measured by the ACE ULEIS
instrument. For these electron events, only ∼35% are associated with a
reported GOES SXR flare, but ∼60% appear to be associated with a CME,
with ∼50% of these CMEs being narrow. These electrons are often
detected down to below 1keV, indicating a source high in the corona.
Description:
The WIND spacecraft was launched on 1994 November 1, with a trajectory
consisting mostly of highly elliptical earth orbits (apogees
∼60-100RE) or orbits around the Lagrange 1 point. The 3D Plasma and
Energetic Particle (3DP) instrument on WIND has been operating
nominally since launch to the present time, and it provides full
three-dimensional measurements of electron distributions from solar
wind thermal plasma to ∼400keV with high sensitivity.
We surveyed the WIND/3DP electron data from 1995 January 1 through
2005 December 31, and identified 1191 solar electron events (see Table
2) based on the detection of velocity dispersion -- the faster
electrons arriving earlier at 1AU than the slower electrons -- of the
flux increase (at the >2σ level) over background (the pre-event
background plus instrumental background) in three or more energy
channels between ∼0.1-310keV.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 117 1191 The list of solar energetic electron events
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See also:
VI/138 : Sunspots catalogues, 1853-1870 (Casas+, 2013)
J/ApJ/757/94 : Solar flares observed with GOES and AIA (Aschwanden, 2012)
J/ApJ/747/L41 : Solar flares probabilities (Bloomfield+, 2012)
J/ApJ/737/L35 : Pulsed Alfven waves in the solar wind (Gosling+, 2011)
J/ApJ/721/901 : Solar quiescent filament channels (Su+, 2010)
J/ApJ/710/1111 : Observations of interplanetary shocks (Gopalswamy+, 2010)
J/ApJ/710/L58 : Coronal type II radio bursts in 2002 (Lobzin+, 2010)
J/ApJ/709/1238 : Solar Coronal Mass Ejection (Yeates+, 2010)
J/A+A/390/717 : Solar Veloc. of the Sun in 1989-99 (IRIS++) (Salabert+, 2002)
J/A+A/375/614 : Astrolabe observations of the Sun in 1990-2000 (Noel, 2001)
J/A+AS/130/233 : WATCH Solar X-Ray Burst Catalogue (Crosby+ 1998)
J/A+AS/110/99 : White-light flares models (Fang+, 1995)
J/A+A/304/563 : Cool X-ray flares of Sun with GOES (Phillips+, 1995)
http://cdaw.gsfc.nasa.gov/CME_list/ : SOHO LASCO CME online catalog
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "YYYY/MM/DD" Date Date of the observation
12- 14 I3 d DOY Day of the year
16- 20 F5.2 h Obs.h Hour of electron solar injection (1)
22- 27 F6.3 keV Emin [0.04/66] Lowest energy
29- 34 F6.2 keV Emax [1.1/520] Highest energy
36- 47 A12 --- 3He/4He He description ("3He rich" or
"not 3He rich" or "n/a")
49- 51 A3 --- T-III [yes/no ] Type III event?
53- 55 A3 --- T-II [yes/no ] Type II event?
57- 59 I3 deg PA ? Coronal mass ejection (CME)
position angle (2)
63 A1 --- f_PA [nha] Flag on PA: n=no event, h=halo,
a=no data)
66- 68 I3 deg CME-W ? CME width (2)
72 A1 --- f_CME-W [nha] Flag on CME-W (n=no event,
h=halo, a=no data)
75- 78 I4 km/s CME-V [46/2861]? CME speed (2)
81 A1 --- f_CME-V [na] Flag on CME-V (n=no event, a=no data)
84- 91 A8 "h:m:s" Time GOES soft X-ray (SXR) start time; UT (3)
93- 97 I5 min Dur [-1429/430]? GOES SXR duration (3)
99-102 A4 --- Class Geostationary Operational Environmental
Satellite (GOES) SXR class (B1.2-X28) (3)
104-109 A6 --- Floc Flare location (3)
111-117 A7 --- p10M GOES >10MeV proton event? ("no", "yes",
or "no data") (4)
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Note (1): Estimated from the highest energies detected in the event.
Note (2): The CME information is from the SOHO LASCO CME catalog
(http://cdaw.gsfc.nasa.gov/CME_list/), after subtracting the photon
travel time of 500s.
Note (3): The GOES proton information is from the Solar Geophysical Data
(SGD) (ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/ [ftp.ngdc.noaa.gov]),
after taking into account the photon travel time of 500s from the Sun
to 1AU. The SXR duration is end-start time.
Note (4): The GOES >10MeV proton event with the peak flux above
1/cm2/s/sr after subtracting pre-event background.
The GOES proton information is available since 1996, from
http://www.swpc.noaa.gov/ftpmenu/warehouse.html.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 10-Jul-2014