SPEED EVOLUTION OF CME/SHOCKS USING
MULTI-SPACECRAFT OBSERVATIONS OF
TYPE II RADIO BURSTS.
T. Manuel-Hernández, E. Aguilar-Rodriguez
and A. Gonzalez-Esparza
Instituto de Geofísica UNAM, Unidad Michoacán
* Objetive
To determine the propagation of large-scale
disturbances
in
Solar
Wind
using
interplanetary
Type
II
radio
burts
observations, detected by Wind/WAVES and
STEREO/SWAVES in the ascending phase of
the solar cycle 24.
Metric
DH
Kilometric
* Objetive
Type II
emission
To determine the propagation of large-scale
disturbances of Solar Wind by using Type II
radio burts observations in the frecuency
Type II
emission
range DH-km,
detected by Wind/WAVES and
STEREO/SWAVES in the ascending phase of
solar cycle 24.
CMEs driven shock
(Flares/CME)
CMEs driven shock
(Cane, 1987).
Type II radio burst
In this Study we have considered 24 IP Type II
radio bursts observed by the three radio
experiments and its corresponding solar event.
In some cases we included the metric
counterpart of each type II radio observed by
ground-based radio intrument.
Type II radio bursts observed
by Wind/WAVES and STEREO/SWAVES
How to track the heliocentric
evolution of fast CME/shocks?
CME/shock speed determination
Reiner et al., (1998) showed that if we asume that the shock speed
is constant and the plasma frequency decays as 1/R2, then the Type
II emission is organized along a straight line.
The frequency drift rate of a Type II emission generated by a CMEdriven shock can provide direct measumerent of the shock speed.
Assuming that the schock speed (v) is constant during a short
interval and the solar wind is decreasing as 1/R2
knowing the
slope of the frecuency drift and the solar wind density at 1 AU (no)
we can aproximate the speed of the shock causing the emission:
V is shock speed, n0 is the density normalized to 1AU, R0=1.5x10⁸ km, a=9 if the emission is Fundamental
(F), and a=18 if the emission is harmonic (H).
Speed determination technique
(a) Type II radio burst dynamic
spectrum.
(b) isolated Type II event.
(c) for every radio spectrum (1
min res.) we apply a Gaussian
fit (dashed line)
to the flux
density
distribution
vs
frequency to determine the
central frequency.
(d) to study the frequency drift
associated with the km-TII
burst
we
select
some
intervals.
(e) we calculate the slope for
subintervals of at last 60
minutes to obtain the speed
solutions distribution
- report the mean speed
and its standard deviation
for the interval
Bisi et al., 2010
Speed evolution
Solid-Circle: Shock
speed of the radio
kilometric Type II
burst drift.
Triangle: initial
speed white-light
Solid-Diamond:
speed interplanetary
scintillation
Bisi et al., 2010
Cases Study
We took a sample of three Type II
radio burst observed by the three
spacecraft.
1st case study: 2007/01/25
Time Central
PA
06:54
Halo
Angular
Width
360
Vel.
(km/s)
1367
SOHO-LASCO
Position of STEREO
C6.3
22.800 21.168
43.969
GOES
Separation angle with Earth
Separation angle A with B
Loc.
A.R Clas.
Time
S08E90 10940 C6.3 0633 0758 0714
Dynamic Spectra
Central Frequencies
Type II radio burst
Int 1
Type II radio burst
Int 1
Type II radio burst
Speed evolution
Metric: The shock
speed using the
Newkirk’s density
model.
SA-radio and
Wind-RAD1:
obtained from the
analysis technique
using kilometric
Type II radio
observations.
2nd case study: 2011/11/26
Time
07:12
Central
PA
Angular
Width
HALO
360
Vel.
(km/s)
933
SOHO-LASCO
Position of STEREO
C1.2
GOES
Separation angle with Earth
Separation angle A with B
103.163
105.894
150.941
Loc.
N08W52
A.R
Clas.
Time
11353 C1.2 0609 0710 0756
Time
07:24
Central
PA
323
Angular
Width
352
Time
Vel.
(km/s)
07:24
543
Central
PA
356
SOHO-LASCO
07:12
Central
PA
HALO
Vel.
(km/s)
286
595
SECCHI-A
SECCHI-B
Time
Angular
Width
Angular
Width
360
Vel.
(km/s)
933
Dynamic Spectra
Central Frequencies
Type II radio burst
Int3
Int1
Type II radio burst
Int1
Type II radio burst
Int2
Speed evolution
SA-radio and
Wind-RAD1:
obtained from the
analysis of the
radio kilometric
Type II burst drift
3rd case study: 2012/03/05
Position of STEREO
Time Central Angular
Vel.
PA
Width
(km/s)
02:54 332
302
781
SOHO-LASCO
Time Central
PA
03:24
321
Angular
Width
Vel.
(km/s)
244
781
Dynamic Spectra
Central Frequencies
Type II radio burst
Type II radio burst
Type II radio burst
int1
Speed evolution
Conclusions
We analyzed a list of Type II radio burst with their
corresponding solar association (CMEs and Flares).
From the list, we selected 24 Type II radio bursts observed
by the three radio experiments.
We analyzed WIND/WAVES and STEREO/SWAVES radio
data associated with CME/shocks. We applied a technique
to infer the shock propagation speed at some intervals.
We combined differents observations to infer the evolution
speed of CME/shocks. Observations in white-light by
SOHO-LASCO and SECCHI-AB, as well as in-situ
observations, at diferents times covering different
heliocentric distances .
The three events analyzed show a gradual deceleration as
they propagate through the heliosphere.