Abstract 

Our understanding of the Universe has undergone a revolution over the past century, revealing a cosmos governed by dark energy, shaped by dark matter, and expanding ever faster. We are now at a stage where cosmology has transformed into a precision science. In this talk, I will introduce the key concepts and challenges of our standard model of cosmology. I will highlight recent insights from major experiments, including the Atacama Cosmology Telescope (ACT), which has refined our view of the cosmic microwave background, and the Dark Energy Spectroscopic Instrument (DESI), which is mapping the large-scale structure of the universe with unprecedented precision. Finally, we will reflect on the capabilities of experiments such as the Vera C. Rubin Observat

By: Dr Chandra Shekhar Saraf 

Affiliation: Korea Astronomy and Space Science Institute (KASI), 

South Korea

Presenter: Christian Ikechukwu Eze 

Affiliations: University of Nigeria, Nsukka, Nigeria and Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland 

Abstract: 

Massive stars occur mostly in binaries or multiples, with some hosting pulsating components. Just as the sound of a guitar is produced when its strings excite resonances in the guitar body at natural frequencies, the energy trapped within a star causes it to oscillate at its natural eigenfrequencies. These pulsations cause the outer layers of the star to vary in brightness as it expands and contracts. These rare systems, where massive stars both pulsate and orbit in eclipsing binaries, offer an unparalleled laboratory for probing the internal physics of high-mass stars. The combination of precise photometric and spectroscopic data from eclipses with asteroseismic signals gives new insights into stellar interiors, including core structure, rotational profiles, and mixing processes. Leveraging data from space-based missions such as Kepler and TESS, alongside ground-based campaigns, this seminar explores how the interplay between stellar pulsations and binary interactions enables precise constraints on fundamental stellar parameters and evolutionary pathways of massive stars. Join us as we decode the rhythmic pulses of the cosmos and uncover the hidden symphony within these extraordinary stellar duets.
 

Biography

Christian Ikechukwu Eze is a Nigerian astrophysicist and lecturer at the Department of Physics and Astronomy, University of Nigeria, Nsukka (UNN). He is also a doctoral researcher at the Nicolaus Copernicus Astronomical Center (CAMK) in Warsaw, Poland and currently on a three-month research visit (funded by Bekker NAWA fellowship programme) to the Institute of Astronomy, KU Leuven, Belgium. His doctoral research focuses on the asteroseismology of massive stars in eclipsing binaries, contributing to the OPUS research project funded by the Polish National Science Center (NCN). Eze's major research interests encompass asteroseismology, stellar variability and spectroscopy. He has published several articles in reputable journals and received outstanding academic awards. Beyond his academic pursuits, Eze has been actively involved in international collaborations. He served as a Consortium Board member and UNN Local Contact Person for the Pan African Planetary and Space Science Network (PAPSSN). Currently, he is a member of the consortium and the leader of Task 3.1 of Work Package 3 in the Focus on Africa Space Science and Technology for Future Development (FAST4Future). Eze is affiliated with professional organizations such as the African Astronomical Society (AfAS) and the Astronomical Society of Nigeria (ASN), reflecting his commitment to advancing astrophysical research and education.

On the Evolution of Eccentric Ellipsoidal Variables 

by Dr Piotr Kołaczek-Szymański 

University of Liège, Belgium 

Abstract 

Currently, we know that stellar binarity is a common phenomenon, particularly important for massive stars whose evolutionary tracks are predominantly affected by the presence of a (nearby) companion. Moreover, a significant fraction of binary systems at various stages of their evolution is characterized by eccentric orbits, either due to their relatively young age or eccentricity-pumping mechanisms. Hence, the close investigation of eccentric binary systems is crucial for the verification of various tidal interaction theories that greatly influence our predictions of the evolution of these objects. During the seminar, I will focus on eccentric ellipsoidal variables (EEVs), occasionally dubbed as "heartbeat stars"), tidally excited oscillations and their impact on the evolution of EEVs. Additionally, I will discuss other effects associated with the periastron passages that can mimic EEVs, such as massive systems with stellar wind collisions.

Date: Friday  7th March 2025 ; 1400- 1510 hrs (CAT)

Platform: FAST4Future and Botswana Academy of Science Platforms

Organisers: The Organization for Women in Science for the Developing World (OWSD) - Botswana National Chapter, Botswana Academy of Science and FAST4Future

Platform: 

Teams Meeting ID: 392 715 344 263

Passcode: KH3FA259

The volcanic moon Io and its role in Jupiter's vast magnetosphere

By Associate Professor Lorenz Roth

School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm, Sweden

Abstract

Since the Voyager mission flybys in 1979, we have known Jupiter moon Io to be extremely volcanically active as well as to be the main source of plasma in the vast magnetosphere of Jupiter. While the volcanic activity is generally dynamic and variable, the Jupiter magnetospheric plasma environment is stable on timescales from days to months. However, various observations suggest that occasionally (roughly 1-2 times per decade) the plasma environment undergoes major transient changes over several weeks, apparently overcoming any stabilizing mechanisms.

I review the current knowledge on Io’s volcanic activity, atmosphere and the magnetospheric neutral and plasma environment in view of their roles in the mass transfer from Io to the plasma torus and magnetosphere. At the end, I will briefly discuss what current and future space missions (Juno, JUICE, Europa Clipper) might contribute to address this topic.

About the Speaker

Associate Professor Lorenz Roth is a planetary astronomer and physicist specialized in imaging data analysis and modeling. His research deals with the magnetospheric environments, atmospheres, surfaces, and interiors of various planetary bodies. The focus of most of my recent studies lies on the Galilean moons of planet Jupiter: Io, Europa, Ganymede, and Callisto. He is involved in projects on the auroral emission from the ice giants Uranus and Neptune, the rings of Saturn, and ultra-cool dwarf stars. Most of my studies are based on observations by the NASA/ESA Hubble Space Telescope (HST), for which I am leading several observational campaigns, as well as from ground-based telescope facilities, including the ALMA observatory.

Ionospheric waves 

by

Dr Alicreance Hiyadutuje 

Date: February 11, 2025 from 11:00 AM West African Time (WAT)

Venue: Online via zoom (link is given below, check also https://lms.cesst.org/ ) 

Abstract 

The law of conservation of energy state that: “energy is neither created nor destroyed”, it can only change into different forms, that is called the transformation and/or can move from one place to another, that is known as the transfer. Most of the Earth’s magnetospheric energy input comes from the Sun as solar wind, Coronal Mass Ejections known as the CMEs, and solar flares. As a result this energy input, different phenomena may take place within the magnetosphere. Waves are examples of some of the phenomena that are caused by the space and/or terrestrial weather. Types of waves are given . For example, Atmospheric waves such as planetary, tides, and Atmospheric Gravity Waves (AGWs) are defined. AGWs, Perkins Instability and other mechanisms that cause the Travelling Ionospheric Disturbances (TIDs) are described. Groups of AGWs/TIDs are discussed. At the end of the presentation, other different mechanisms that can cause TIDs are discussed. Based on the previous results, we also discuss TIDs impacts on the High Frequency (HF) communication.

Biography of Dr. Alicreance Hiyadutuje 

Dr. Alicreance Hiyadutuje is a physicist specializing in ionospheric studies. He holds a Ph.D. from the University of Kwazulu Natal (UKZN). Professionally, Dr. Hiyadutuje has held various teaching positions, including teaching natural sciences and tutorial assistant and assistant lecturer in physics at different institutions. Currently, he is a Postdoctoral Researcher at the South African National Space Agency (SANSA), studying ionospheric irregularities. His research primarily centers on ionospheric disturbances during magnetic storms. Dr. Hiyadutuje's work has been recognized within the academic community, with publications in the Journal of Geophysical Research (JGR) and the Journal of Atmospheric and Solar-Terrestrial Physics (JASTP). He attended different conferences at SuperDARN, IUGG, IAGA-IASPEI, and AGU. Notably, he has explored the modulation of E-region near-range echoes by Traveling Ionospheric Disturbances also known as TIDs, as detailed in his publication "First Observations of E‐Region Near Range Echoes Partially Modulated by F‐Region Traveling Ionospheric Disturbances Observed by the Same SuperDARN HF Radar."

Join Zoom Meeting
https://unn-edu-ng.zoom.us/j/96501130001?pwd=F7GfkMSNBZ1dt0aIuG1FLhtbuIvY0S.1

Meeting ID: 965 0113 0001
Passcode: 827545

Date: January 28, 2025 

Time: 11 – 15 hrs (WAT) 

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 https://lms.cesst.org/login/index.php