UAAT International Young Visiting Scholar Program
Niki Xirogiannopoulou, Ph.D.
Current Position/Title:Postdoctoral Researcher
Institutional Affiliation:Department of Surface and Plasma Science, Charles University of Prague
Email: niki.xirogiannopoulou@matfyz.cuni.cz
Webpage: https://orcid.org/0000-0002-7990-5050
Host Scholar: Wei-Ling Tseng, Associate Professor
Hosting Department: Department of Earth Sciences, National Taiwan Normal University
Biography:
Niki Xirogiannopoulou is a space physics researcher that obtained her doctoral diploma from the Charles University in Prague. Despite having a bachelor’s degree in mathematics from the National and Kapodistrian University in Athens, she switched her interest to Plasma Astrophysics, studying for her master’s in the Centre for mathematical Plasma Astrophysics (CmPA) of KU Leuven. Her doctoral research investigated the terrestrial magnetospheric dynamics, focusing mainly on the foreshock transients and their impact to the magnetosheath (Dissertation: Foreshock Subsolar Compressive Structures and their Impact in the Magnetosheath). Using multi-spacecraft observational data from MMS and THEMIS, she showed that there is no direct connection between the foreshock subsolar compressive structures and the magnetosheath jets. Overall her research interests and publications are revolving around Solar Wind, Interplanetary Magnetic Field, Foreshock, Bow Shock, Magnetosheath, Magnetosheath Jets, Magnetospheric Environments, Data Analysis, Simulations. In this research visit in NTNU, she hopes to apply and test her previous findings to the Martian Magnetospheric environment.
Lecture [1]:
Date ＆ Time: 2026-09-24 (Thu), 12:20-13:20
Venue: Education and Research Building S801-2, National Taiwan Normal University (Gongguan Campus)
Title: Foreshock Subsolar Compressive Structures and their Impact in the Magnetosheath
Abstract:
The turbulent region upstream of the quasi-parallel bow shock, called the foreshock, consists of back-streaming particles and waves that interact with each other and create different transients that impact their surroundings and the downstream plasma. We focus on the compressive transients detected in the subsolar foreshock region. Using spacecraft data from the Magnetospheric Multiscale Spacecraft (MMS) mission, we conduct a statistical analysis on the characteristics and the occurrence rate of the different types of compressive structures, such as plasmoids, SLAMS and mixed structures. We find that the fast or very dense solar wind increases the probability of appearance of all the structures, as well as, the modification of the solar wind in the foreshock. Additionally, we present a multi-spacecraft analysis, based on MMS, THEMIS and OMNI measurements, to explore the relationship between the foreshock compressive structures and the magnetosheath jets. Based on the results obtained, we propose that the dominant formation mechanism of the jets in the magnetosheath is bow shock reformation, driven by steep and rapid changes in the upstream magnetic field orientation. Our findings demonstrate that the appearance of the magnetosheath jets is not directly connected with the foreshock compressive structures. Although the presence of plasmoids and SLAMS is not essential, they may contribute as a part of the random fluctuations involved in the creation of magnetosheath jets. In this respect, the level of the solar wind modification in the foreshock, rather than the pristine solar wind itself, governs the occurrence rate of the transients around the bow shock.
Lecture [2]:
Date & Time: 2026-10-05 (Mon), 15:00-16:00
Venue: Department of Space Science and Engineering, National Central University
Title: A comparative study of foreshock compressive structures at the terrestrial and Martian magnetospheres
Abstract:
In planetary magnetospheric systems, the turbulent region upstream of the bow shock, called the foreshock, consists of back-streaming particles and waves that interact with each other and create different transients that impact their surroundings and the downstream plasma. Foreshock transients play a key role in the solar wind-planetary coupling. In the terrestrial environment, these structures can propagate via different mechanisms, reach, impact the magnetopause – the dynamic boundary separating the solar wind from terrestrial magnetic field, and trigger magnetospheric disturbances. However, it is unclear to what extend similar processes operate in Mars, an unmagnetized planet with different dissipation mechanisms. By investigating these phenomena across two different planetary systems, we attempt to address the broader question of whether the foreshock processes are universal and how they are modulated (and modulating) under different magnetic field and plasma interactions. Using spacecraft data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission, we conduct a statistical analysis on the characteristics and the occurrence rate of the different types of foreshock structures of Mars. Based on previous results obtained by Xirogiannopoulou et al. (2024, 2026), we compare the terrestrial and Martian structures in order to understand the effects of the different magnetic topology in their characteristics, evolution and impact.