Séminaires

The bright future of X-ray polarimetry
Frédéric Marin (Observatoire de Strasbourg)

Salle de réunion AGO (local -1/14), Institut d'Astrophysique et de Géophysique
Bâtiment B5c, Quartier Agora, Allée du 6 Août, 19C, B-4000 Liège 1 (Sart-Tilman)

50 years after the pioneering experiments, X-ray spectroscopy and timing techniques can be considered as well established. Nonetheless, one prominent feature of X-ray light has not been explored as scrupulously as others: its polarization. Between 1980 and 2000, the instruments were not sensitive enough to go beyond the first X-ray polarimetric results acquired in the 70s but the development of new detection techniques in the early 2000s revived the field. The first X-ray spatial mission to fly a new generation polarimeter will be launched by NASA in 2021 and a couple of balloon-borne experiments are being considered. Following the increasing interest of the community to the unexplored phase space of X-ray polarization, I will present the discoveries X-ray polarimetry is about to make.


Café, thé et biscuits seront servis après le séminaire...

Study of comets using TRAPPIST telescope network.
Franscisco Pozuelos Romero (STAR Institute)

Salle de réunion AGO (local -1/14), Institut d'Astrophysique et de Géophysique
Bâtiment B5c, Quartier Agora, Allée du 6 Août, 19C, B-4000 Liège 1 (Sart-Tilman)

Comets are remnants of the early stages of the Solar system and, likely, the most pristine solar system bodies. Understanding their nature and their evolution is a must to understand the history of our Solar System. Comets contain complex organic molecules, and may have played a key role in the transfer of water and organics from the interstellar medium to the early Earth, contributing to the origin of life. This interest is well illustrated by the fact that several space missions have targeted small bodies of the solar system, and particularly comets like the very successful ESA Rosetta/Philae mission currently returning impressive science data that are going to revolutionize our knowledge of comets. The nucleus of a comet, typically a few kilometers in diameter, is essentially composed of water ice mixed with carbon oxides, methane, ammonia, and dust particles. When the comet approaches the Sun, the ices sublimate, forming a gaseous and dusty coma. Solar radiation and wind blow this material to form spectacular cometary tails. Investigations of the chemical composition of comets are important for a variety of reasons. In addition to revealing the characteristics of comets themselves, the composition of comets holds unique clues to conditions in the early solar nebula and the Solar System’s formation processes, since comets remain the most pristine objects available for detailed studies. In particular, knowledge of the bulk chemical composition of comets and how the composition varies among individuals and/or with exposition to solar radiation can provide strong constraints on the composition and temperature of the proto-planetary nebula at the time solid bodies began to form some 4.6 billion years ago. Depending on the region of formation in the protosolar nebula, comets are currently stored in three main reservoirs: the Oort cloud, the Kuiper belt and the main asteroid belt. By studying comets from different reservoirs we can probe the different environments in which they formed, and also better understand their role in the Solar system as suppliers of water and organics.


Café, thé et biscuits seront servis après le séminaire...

TBA
Beomdu Lim (STAR Institute)

Salle de réunion AGO (local -1/14), Institut d'Astrophysique et de Géophysique
Bâtiment B5c, Quartier Agora, Allée du 6 Août, 19C, B-4000 Liège 1 (Sart-Tilman)


Café, thé et biscuits seront servis après le séminaire...

TBA
Maxim Laletin (STAR)

Le lieu où se tiendra cet évènement n'est pas encore déterminé...

Gravitational waves: origins, detections, implications.
Gustavo E. Romero (IAR, CONICET / University of La Plata, Argentina)

Salle de réunion AGO (local -1/14), Institut d'Astrophysique et de Géophysique
Bâtiment B5c, Quartier Agora, Allée du 6 Août, 19C, B-4000 Liège 1 (Sart-Tilman)

The existence of gravitational waves was predicted by Albert Einstein 100 years ago. Their detection has being extremely elusive and difficult. It was finally achieved with the gigantic laser interferometer LIGO in 2015. Since then, several events produced by the coalescence of binary black hole systems have being detected and measured. In this talk I will review the nature of gravitational waves, discuss how they can be detected depending on their frequency, and elaborate about the implications of this momentous discovery.

TBA
Jean-Philippe Lansberg (I.P.N., U. Paris Sud)

Le lieu où se tiendra cet évènement n'est pas encore déterminé...