Aust. J. Phys., 1994,47,817-19
1994, 47, 817-19
Solar Flare Surges in relation to
Active Prominences and Sunspots
T. K. Das, T. N. Chatterjee and A. K. Sen
Eastern Centre for Research in Astrophysics,
Institute of
of Radio Physics and Electronics,
92, A.P.C. Road, Calcutta 700009, India.
Abstract
A study has been made of flare
flare surges (FS) after correlating them with prominences and
sunspots. Results obtained are:
are: (i) the duration of the 88% events lies between 0-40 min;
(ii) in most cases the distance between FS
FS and filaments ranges from
from o·
o· 03Ro to
to o·
o· 12Ro
whereas that between FS and sunspots ranges from
whereas'
from o·
o·05Ro to O·
O· 25Ro; (iii) there are several
active regions which can produce sympathetic FS; and (iv) the number of
of FS from
from a particular
to the number of X-ray flares from
from the same active region.
sunspot group is proportional to
1.,
1. Introduction
Flare surges (FS) are straight or slightly curvilinear spikes which, in general,
grow rapidly from small roundish luminous knots of diameter about 20,000 km.
These knots form the basis, possibly even the source, of the surges (Giovanelli and
McCabe 1958). Unlike coronal mass ejections (CME), flare surges are small-scale
phenomena which are generally confined events and which do not escape from
the corona. Several studies on CMEs which escape from the solar corona have,
however, been performed from time to time by various workers (Martens and
Kuin 1986; Kalhler 1987; Gopalswamy and Kundu 1990). As there has been no
systematic study on flare surges, an attempt is made in this research note to
investigate some aspects of this phenomenon in the solar atmosphere in relation
to active prominences and sunspots.
2. Data Collection and Method of Analysis
About 140 FS events which occurred during 1988 were
were collected from Solar
Geophysical Data Bulletins published by NOAA (US Department of Commerce).
We considered only those events which occurred far inside the solar disk, as it
was not possible to
to get any information about the surge or associated sunspots
situated near the limb.
As the locations of FS are given in R.A. and R/R
Rj Roo ::::::
= r coordinates, we
converted them to LAT.
LAT. and CMD with the help of requisite relations. The
distances between FS and active prominences, as well as between FS and sunspots,
were evaluated from similar formulae.
In associating the active prominences with the FS, it was observed that in
were temporally and spatially connected, each having the
about 137 cases they were
same starting and ending times. A sunspot was said to
to be
be correlated with an
0004-9506/94/060817$05.00
T. K. Das et al.
818
FS when they occurred within 0·5R
FS
o· 5Roo with respect to each other, and about 131
such cases were found from the above-mentioned surges.
3. Results
Duration of Flare Surges
The durations of the various surge events were studied and the results are
in Fig. la.
1a. It is observed that in about 88% of cases the duration lies
shown in
between 0 and 40 min. In the next phase we attempted to
to find out whether
this duration was
was influenced by a variation in the area and magnetic field of
the associated sunspot. They were, however, found to be very poorly correlated,
signifying that the lifetime of
of a surge is not governed by the strength of the
underlying magnetic field, or
or by the area of the nearby active region.
Coexistence of Surge, Filament and Sunspot Group
The separations between surge and filament and also
also surge and sunspot group
were separately evaluated by employing proper latitude corrections. The results
c. From Fig. 1
are displayed in
in Figs 11bband
and 1Ic.
1bb it
it is evident that in
in about 86%
03 to
l2Ro.
of cases the distance between surge and filament ranges from .0·
0·03
to O·
O· 12R
o.
it appears that the distance between surge and sunspot
Similarly, from Fig. 1c
Ic it
varies between o· 05R
05Roo and O· 25Ro in about 86% of cases.
Sympathetic Flare Surges
it is observed that the same sunspot group
While associating FS
FS with sunspots, it
may produce several surges in
in a sequence, at different intervals of time. These
may be
be termed 'sympathetic' surges, similar to sympathetic flares and radio
~ 50
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(a)
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10 11 12
1 2 3 4 5 6 7 8 9 101112
III
o
10
oci
Z
z
6
Distance between
Ro)
between filament and FS (0'01 Ra)
Duration of FS (min)
'0
o
(b)
0o
.~
"-5i
.~
o
10
20
30
30
40
40
Distance between sunspot and
(0'01 Ro)
FS (0'01Ra)
Number of FS from a particular
Number
sunspot group
of flare surges
Fig. 1. Histograms showing the frequency distribution of
of (a) the duration of
(FS), (b)
(b) the distance between sunspots and FS,
FS, (c) the distance between filaments and FS,
and (d) a bar diagram showing sympathetic FS
FS from
from a particular sunspot group.
819
Solar Flare Surges
60
'"en
(])
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~ 40
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X
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20
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E
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o
4
8
12
Number of FS
Fig. 2. Regression line giving the variation of the number
of X-ray flares
flares with that of flare surges associated with a
particular active region.
bursts. The bar diagram in Fig. 1 d gives some idea of the surge productivity
of sunspot groups. It is found that there is a considerable number of sunspots
whose surge productivity is quite high.
whose
with X-ray Flares
Association with
We have observed that there is no temporal or spatial coherence between surge
and X-ray flares, but the sunspot groups which were more surge productive were
found to be very active in generating X-ray flares. For this study we noted that
the number of FS, as well as the respective number of X-ray flares, occurred
from a particular sunspot group possessing higher activity. It is observed from
Fig. 2 that the number of FS from a particular sunspot group increases linearly
with the number of X-ray flares from the same sunspot group. In this case a
correlation of about 52% has been obtained, and the best fit gives the following
empirical relationship:
Number of X-ray flares === 3x(Number
3x(Nunlber of surges)
+ 1·5.
Acknowledgment
One of the authors (TNC) acknowledges CSIR (Govt of India) for support of
the present work.
References
Giovanelli, R. G., and McCabe, M. (1958). Aust. J. Phys. 11, 191.
19l.
Gopalswamy, N., and Kundu, M. R. (1990). Astrophys. J. 365, L31.
L3I.
Kalhler, S. (1987). Rev. Geophys. 25, 663.
Martens, P. C. H., and Kuin, N. P. M. (1986). Sol. Phys. 122, 263.
Manuscript received 8 June, accepted 4 August 1994