Graduate School in Physics and Astrophysics ------------------------------------------- ANNUAL REPORT ------------------------------------------- Fill with a text editor (without TAB or formatting) Repeat fields for each course as necessary. ------------------------------------------- name: Frassati Federica email: frassati@oato.inaf.it ciclo: XXXI year completed (1,2 or 3): 3 supervisor: Bemporad Alessandro (INAF - OATo) ------------------------------------------- ------------------------------------------- ------------------------------------------- CONFERENCES, WORKSHOP (only those attended in the current year) title: Proba-3 Science Working Team place: Noordwijk (NE) webpage: https://www.cosmos.esa.int/web/proba-3-swt/agenda2 days: 27-28 september talk or poster (Y/N): talk ------------------------------------------- VISITS AND STAGES (only those done in the current year) institution: IAPS -INAF ROMA place: ROMA (Italy) starting date: 3 May 2018 days: 11 --------------------------------------------------- Research activity/Publications in the current year Research activity: My research activity is focused on Interplanetary Shocks(ISs) driven by Coronal Mass Ejections (CMEs). The study is based on data acquired by space-based amd ground-based instrumentations. In this last year I conclude the analysis of the event happened on 1st November 2014: we present a detailed investigation of the CME-driven shock associated with this event following the early evolution of the compression front observed near the Sun up to the extended corona. Our aim is to shed light on the long-debated issue concerning the location and timing of shock formation in the corona. Through differential emission measure analysis we derived, for the first time, the compression ratio across the expanding EUV front observed by AIA at different temperature ranges: higher compression ratios corresponded to higher plasma temperature ranges, as expected. Moreover, comparison between up- and down-stream temperatures and those expected via adiabatic compression shows that no additional heating mechanisms occurred in the early front expansion phase, implying that the shock formed beyond the AIA field of view. Finally, the analysis of the associated type II radio burst, in combination with the inferred coronal density distribution, allowed us to identify a well-defined region located northward of the CME source region as the site for shock formation and to outline its kinematics in accordance with the evolution of the expanding front as obtained from the EUV and WL data. In collaboration with Dr. Salvatore Mancuso another event,happenes on 30 October 2014, was studied and the main preliminary results are: 1) The compression ratio derived from the DEM method in the region corresponding to the type-II as derived from the NRH images is compatible, within the given uncertainties, to the one obtained independently from the band-splitting. The compression ratio in this region was also found to be larger than those in other directions. Bemporad & Mancuso (2011) suggested that type II radio bursts are likely to be generated at the nose of the shock because shock speeds there are usually larger than at the flanks. For this event, however, the type-II radio source was mainly propagating non-radially and was generated in a portion of the disturbance where the Alfven Mach number M_a was largest (thus implying a stronger disturbance) whereas the disturbance speed was not (the disturbance can non-linearly steepen into a shock when M_a is large enough). In this particular event, the disturbance speed was thus not a sufficient condition for producing the type-II radio burst: a larger Alfven Mach number is more likely the condition for the generation of the burst. 2) We estimated the coronal magnetic field with three different methods: i) the band-splitting method, ii) the standoff distance method (Gopalswamy & Yashiro 2011), and iii) the method used by Kumari et al. 2017. The results from the three methods were found compatible within the given uncertainties. The derived profile was compared with values and models obtained in the literature and with the one derived from a simple potential extrapolation (PFSS) at the relevant height. An article of this study is under preparation. During the visit at the IAPS-INAF Institute in Rome I collaborated with Dr. Monica Laurenza to study the CME driven shock and SEPs fluxes for the event happened on 21 June 2013. The strategy is to measure the shock properties (compression ratio X, shock inclination angle ?, shock speed vS, and shock Mach number MA) all along the magnetic fieldline connecting with the Parker spiral the different S/C sampling energetic particles for this event. We perform the 3D recontruction of the shape of the shock front and kinematic of the expanding front, combining SOHO and STEREO coronagraphic observations. We reconstruct with the in situ data the shape of Parker spiral arms connecting ST-A, ST-B and L1 with the Sun. We plan to combine the above information: -To derive along the interception between the 3D shock front and the spiral arms 1) shock inclination angle ?, 2) shock speed vS, and 3) shock Mach number MA (by assuming extrapolated magnetic field in 3D); -To measure the shock compression ratio at different altitudes from LASCO-C2 and C3 on the ecliptic plane. -To combine all the above information to analyse the SEP spectra detected in situ at ST-A, ST-B and L1 and derive the most probable location in 3D for SEP acceleration region; -To apply radio triangulation technique to identify the most probable location of the type-II radio source, hence the most probable location in 3D of shock formation This year I have been collaborating as a LOC member to organize the SOHE3 meeting (28-31 October 2018, http://sohe3.oato.inaf.it/) and I will attend this conference with a talk contribution. Publication: - COMPREHENSIVE ANALYSIS OF THE FORMATION OF A SHOCK-WAVE ASSOCIATED WITH A CORONAL MASS EJECTION (Frassati et al., ApJ, submitted.) - Radio and EUV analysis of a cme-driven shock (S. Mancuso and F. Frassati, in preparation) Talks: Study of CME-driven shocks: future possibilities with ASPIICS/PROBA-3 (Proba-3 Science Working Team 27-28 September 2018)