X-RAY, gamma-RAY Emission and HIGH-ENERGY charged particles in
near-Earth- space according to CORONAS-F satellite data: from maximum to
minimum DURING the last solar cycle.
S.N. Kuznetsov, I.N. Myagkova, E.A. Muravieva, V.G. Kurt, V.I. Galkin,
B.Yu. Yuskov
[E-mail: irina@srd.sinp.msu.ru]
1. Introduction
Effects of space weather (and space climate) can range from damage to
spacecraft to the disruption of power grids on Earth. The most important part
of this damage is caused by solar energetic particles (SEP) – protons and
electrons. Basic patterns of solar energetic particle transport by
interplanetary shocks were published in e.g. Dorman and Miroshnichenko
(1976). Recent experimental results and theoretical studies show that
interplanetary shocks driven by Coronal Mass Ejections (CMEs)
play a major role in accelerating SEPs (Cane et al
(1988), Berezhko et al (2001)). Direct measurements
of SEP penetration boundary variations at low altitudes are very important for
in the estimation of the local space weather conditions.
Simultaneous measurements of solar flare
electromagnetic emission and charged particles provide us with very useful
information. Soft X-rays (SXR), hard X-rays (HXR) and g-rays produced at the Sun, their time
history and spectrum in a wide energy interval provide us with the most direct
information about particle injection and acceleration processes in solar
flares. It is well known that the solar flare X-ray and g-ray emission
is the result of charged particle interaction with the solar atmosphere - the
superposition of electron bremsstrahlung continuum
and g-ray line emission, e.g. Ramaty
et al. (1988), Ramaty et al. (1994). The observed
hard X-ray and/or g-ray spectrum shows that the
charged energetic particles were accelerated up to rather high energies during
the flare. Solar flare HXR and gamma-ray hardness data is very important in
estimating the possible damage that may be caused by a given flare to technical
systems.
Variations in Earth's Electron Radiation Belts (ERB) and the SEP cut-off
during magnetic storms can also strongly affect the near-Earth environment.
Previous studies have shown the relation between high speed solar winds and ERB
enhancements several days later (e. g. Li et al. (1988)).
The main goals of the Russian solar observatory CORONAS-F (Complex ORbital
Observations in the Near-Earth space of the Activity of
the Sun) were the measurements of solar X-ray and g-ray emission and the study of how SEP events and Coronal Mass Ejections
(CME) influence Earth’s magnetosphere (see in Kuznetsov
et al. (2002)). In this paper we present results related to these goals.
Section 2 introduces the experiments and thereafter the main experimental
results are given.
CORONAS-F was launched into a circular orbit with an inclination of
~82.5o and with an initial altitude of about
3.1 Soft and Hard X-ray emission
The duty cycle for the detection of
solar flares on board CORONAS-F was about 40% as a result of its orbit parameters, so many major flares were lost during
Table 1. Solar
gamma-ray flares detected by
SONG (CORONAS-F) from August, 2001 to
September, 2005.
N |
Data dd/mm/yy |
UT flare according
SXR data (GOES) UT, hh:mm |
SXR class GOES |
Flare coordinates |
AR |
UT Flare according HXR SONG data (>500 keV),
hh:mm |
Emax (channel) SONG, MeV
|
Fluencies (>500 keV 1/(ñm**2) |
Remarks |
1 |
|
X5.3 |
S17E34 |
9591 |
|
60-100 |
7150 |
data till |
|
2 |
|
M6.0 |
N15W31 |
9601 |
|
1.3-4
|
17 |
|
|
3 |
|
M3.4 |
S17E03 |
9607 |
|
.5-1.3 |
4.3 |
|
|
4 |
|
X1.6 |
N15W29 |
9661 |
|
1.3-4 |
112 |
ERB from |
|
5 |
|
X2.8 |
N16E41 |
9733 |
|
7-15 |
78 |
Polar cap |
|
6 |
|
M5.1 |
N12W72 |
9825 |
|
4.4-7.7 |
102 |
|
|
7 |
|
X2.1 |
S21E65 |
9961 |
|
7.7-16.5 |
87 |
|
|
8 |
|
M8.5 |
N22W17 |
0030 |
|
1.6-4.8 |
91 |
Gap |
|
9 |
|
X3.3 |
- |
- |
|
0.6-1.6 |
65 |
ERB from 216:29 |
|
10 |
|
M3.4 |
S10W38 |
0069 |
|
4.8-8.4 |
60 |
|
|
11 |
|
Ì1.4 |
S11W47 |
0069 |
0.6-1.6 |
3.7 |
|
||
12 |
|
X1.0 |
S12W51 |
0069 |
|
4.8-8.4 |
17 |
|
|
13 |
|
X3.4 |
S12W51 |
0069 |
|
4.8-8.4 |
170 |
ERB from |
|
14 |
|
|
M7.1 |
S12W73 |
0069 |
|
0.6-1.6 |
4.5 |
|
15 |
|
X1.5 |
N15E74 |
0095 |
|
4.8-8.4 |
32 |
|
|
16 |
|
|
Ì2.1 |
S25W34 |
0338 |
|
1.7-5.2 |
8 |
|
17 |
|
|
M2.0 |
- |
- |
|
5.2-9.1 |
25 |
ERB from |
18 |
|
|
X1.3 |
S07W17 |
0365 |
23:04-23:07 |
5.2-9.1 |
105 |
ERB from 23:12 |
19 |
28/05/03 |
00:17- 00:27-00:39 |
X3.6 |
S07W17 |
0365 |
00:22-00:29 |
5.2-9.1 |
450 |
ERB till 00:20 |
20 |
29/05/03 |
00:51-01:05- 01:12 |
X1.2 |
- |
- |
01:02-01:07 |
5.2-9.1 |
76 |
|
21 |
23/10/03 |
08:19- 08:35-08:49 |
X5.4 |
S21E88 |
0486 |
08:22-08:30 |
5.2-9.1 |
-- |
inside outer ERB |
22 |
24/10/03 |
02:27- 02:54- 03:14 |
M7.6 |
S19E72 |
0486 |
02:45-02:47 |
0.65-1.7 |
24 |
|
23 |
26/10/03 |
05:57- 06:54- 0733 |
X1.2 |
S15E44 |
0486 |
06:16-06:19 |
0.65-1.7 |
>60 |
ERB till 06:15 |
24 |
28/10/03 |
09:51-11:10-11:24 |
Õ17.2 |
S16E08 |
0486 |
11:02-11:13 |
80-130 |
>9200 |
SEP from 11:13 |
25 |
29/10/03 |
20:37-20:49-21:01 |
X10.0 |
S15W02 |
0486 |
20:40-20:55 |
5.2-9.1 |
1270 |
|
26 |
04/11/03 |
19:29-19:53-20:06 |
X28 |
S19W83 |
0486 |
19:40-19:57 |
130-260 |
>8100 |
ERB
19:40-09:46 |
27 |
17/11/03 |
08:55- 09:05-09:19 |
M4.2 |
S01E33 |
0501 |
08:58-09:03 |
1.7-5.2 |
42 |
|
28 |
20/11/03 |
07:35-07:47- 08:38 |
M9.6 |
N01W08 |
0501 |
08:04-08:18 |
0.65-1.7 |
210 |
|
29 |
06/01/04 |
06:13-06:29-06:36 |
M5.8 |
N05E90 |
0537 |
06:22-06:24 |
1.7-5.2 |
31 |
|
30 |
30/10/04 |
16:18-16:33-16:37 |
M5.9 |
N13W28 |
0691 |
16:24-16:25 |
0.7-1.8 |
14 |
ERB till 16:24 |
31 |
01/01/05 |
00:01-00:31-00:39 |
X1.7 |
N06E34 |
0715 |
00:28-0:32 |
2-6 |
45 |
|
32 |
17/01/05 |
09:59-09:52-10:07 |
X3.8 |
N15W25 |
0720 |
09:52-10:00 |
2-6 |
>25 |
gap
09:16-09:52 |
33 |
20/01/05 |
06:36-07:01-07:26 |
X7.1 |
N14W61 |
0720 |
09:44-09:56 |
90-150 |
3620 |
|
34 |
14/07/05 |
05:57-07:25-07:43 |
M9.1 |
N09W90 |
0786 |
07:23-07:24 |
2-6 |
5 |
|
35 |
09/09/05 |
19:13-20:04-20:36 |
X6.2 |
S12E67 |
0808 |
20:00-20:11 |
6-10.5 |
- |
shade till
20:00 |
36 |
10/09/05 |
21:30-22:11-22:43 |
X2.1 |
S13E47 |
0808 |
21:53-22:03 |
0.75-2 |
9 |
|
37 |
12/09/05 |
08:37-09:03-
09:20 |
M6.2 |
S11E25 |
0808 |
08:46-08:48 |
2-6 |
3 |
|
3.2 Solar proton penetration boundary variations
Due to the orbit of the satellite solar
energetic particles were measured by the CORONAS-F experiment only in the south
and north polar caps during 15-20 minute intervals every ~45 minutes. Hence it
should be highlighted that the solar relativistic electron data (1.5-3, 3-6 and
6-12 MeV) obtained by CORONAS-F from solar maximum
(2001) to solar minimum (2005) are unique. Especially important are the solar
extreme events measured during October and November, 2003 and January 2005.
Solar event studies for November 2001, October-November 2003 and November 2004
were published in papers by Veselovsky et al. (2004),
Panasyuk et al (2004), Yermolaev et al, (2005).
The CORONAS-F experiment (due to its low polar orbit) has demonstrated
that for the estimation of possible SEP damage both the intensity of energetic
solar particles and the data concerning the boundaries of solar particle
penetration in the Earth’s magnetosphere are very important. High energy solar particle penetration in
the polar caps during the main phase of magnetic storms is one of the important
sources of radiation danger in the near-Earth space, especially for
low-altitude satellites. The size of the proton penetration area depends on
proton energy and on geomagnetic conditions. Some earlier CORONAS-F results of
similar studies were published in Panasyuk et al (2004), Kuznetsov et al. (2002), Yermolaev et
al, (2005).
Fig.1. SEP penetration boundary variations during geomagnetic storms
in May 2005. Dst-variation is shown by solid line.
As an example, in Figure 1 we present and discuss the variations
observed in the SEP penetration boundary (or SEP cut-off rigidity variations)
measured by CORONAS-F (protons with energies 1-5 MeV)
during magnetic storms during the time period 19 to 21 August 2002. It is
clearly seen that the proton flux on the penetration boundary does decrease
abruptly. Therefore it is possible to apply different criteria to the analysis
of the penetration boundary position. As was done in Kuznetsov
et al. (2002) and Yermolaev et al, (2005), in this
work we use the traditional “Skobeltsyn Institute of
Nuclear Physics Lomonosov Moscow State University”
criterion – “twice below the maximum of the SEP flux”. The values of
penetration boundary obtained during the morning magnetic local time (MLT) are
marked as plusses, during evening MLT as solid diamonds.
For comparison, time variation of the Dst
index is also shown in Figure
3.3 Outer electron radiation belt variations
Earth’s electron radiation belt (ERB)
dynamics is one of the most important physical processes occurring during
magnetic storms. The upper panels in figures 2a and 2b) show the relativistic
electron dynamics in the outer radiation belt during April-June 2004 (a) and
March-May 2005 (b). The electron flux is shown by grey-scale color. White color
indicates the absence of data mostly connected with telemetry problems. During
both time periods there were no significant solar flares and SEPs according to CORONAS-F (1.5-3 MeV)
measurements. The X and Y axes show the day and the L-shell value respectively.
Middle panel figures show the Dst index, and the
bottom ones the solar plasma wind speed.
It is seen that the most significant
enhancements of relativistic electrons were observed some days after the
occurrence of small magnetic storms connected with incoming high speed solar
wind streams. During the total operation time of CORONAS-F we have found more
than ten such cases. The observed time-delay between solar wind speed
enhancements and relativistic electrons in ERB supports previous work and is
very useful for predictions studies.
Such electrons are sometimes named
"killer electrons" as they are very dangerous to electronic devices,
in particular the microcircuits that are used in space. Relativistic electrons
of the outer ERB produce volumetric ionization in microcircuits of spacecrafts
and breakdown their normal operation. Therefore, the measurement of
relativistic electron dynamics has both practical and scientific interest (e.g.
Myagkova (2005)) and references therein). We suggest
that the high enhancements of relativistic electrons in the outer ERB founded
in CORONAS-F experiment is necessary to take into account for space weather and
space climate studies.
a)
b)
Fig. 2. Relativistic electron flux variation in the
outer ERB in April-June 2004 (a) and March-May 2005 (b) according to CORONAS-F
data. Middle panel shows the Dst index, bottom ones the solar plasma wind speed
In this paper we
have presented observational results regarding X-ray, γ-ray and particle
(protons and electrons) observations obtained by the CORONAS-F spacecraft. The
main results are listed here:
Measurements of solar flare HXR and gamma-ray emission permits one to
estimate the hardness of the flare emission so as to better be able to predict
the possible damage that can be caused by the flares.
The monitoring of SEP penetration boundaries in the Earth’s
magnetosphere is useful also during magnetic storms, since solar energetic
particles can penetrate deep into the Earth’s magnetosphere during the main
phase of even rather weak magnetic storms. In particular due to measurements of the SEP
penetration boundaries one has the opportunity to estimate the radiation damage for different
space missions.
The CORONAS-F observations provide evidence that the observed
significant variations of relativistic electrons in the outer ERB at low
altitudes (from 350 to
Results are important for space weather effect studies, especially how
they are a function of solar activity.
.
Acknowledgements
This work has been partly
supported by grant N 05-02-17487 of
Russian Foundation for Basic Research
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