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 range DH-km, detected by Wind/WAVES and STEREO/SWAVES in the ascending phase of solar cycle 24. Type II emission 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
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 CME-driven 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: Vis 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 Angular Vel. PA Width (km/s) 06:54 Halo 360 1367 SOHO-LASCO Position of STEREO C6.3 GOES Separation angle with Earth 22.800 21.168 Separation angle A with B 43.969 Loc. A.R Clas. Time S08E90 10940 C6.3 0633 0758 0714
Type II radio burst Type II radio burst Type II radio burst Type II radio burst Dynamic Spectra Central Frequencies Int 1 Int 1
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 Central Angular Vel. PA Width (km/s) 07:12 HALO 360 933 SOHO-LASCO Position of STEREO C1.2 GOES Separation angle with Earth 103.163 105.894 Separation angle A with B 150.941 Loc. A.R Clas. Time N08W52 11353 C1.2 0609 0710 0756
Time Central Angular Vel. PA Width (km/s) 07:24 323 352 543 Time Central Angular Vel. PA Width (km/s) 07:24 356 286 595 SECCHI-B SECCHI-A SOHO-LASCO Time Central Angular Vel. PA Width (km/s) 07:12 HALO 360 933
Dynamic Spectra Central Frequencies Type II radio burst Int3 Int2 Int1 Type II radio burst Int1 Type II radio burst
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 Angular Vel. PA Width (km/s) 03:24 321 244 781
Dynamic Spectra Central Frequencies Type II radio burst Type II radio burst Type II radio burst int1
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.