Calendar

Jan
4
mer
Séminaire Philippe Paillou sur le Saharasar @ Salle Atmosphère
Jan 4 @ 11 h 00 min
Séminaire
Jan
11
mer
Séminaire Arnaud Pierens
Jan 11 @ 11 h 00 min
Séminaire
Jan
18
mer
The Quest for the Gravitational-Wave Stochastic Background, Tania Regimbau (OCA) @ Salle Univers
Jan 18 @ 11 h 00 min
Séminaire
Jan
23
lun
Séminaire de Chiara Ferrari @ Salle Univers
Jan 23 @ 11 h 00 min
Séminaire
Fév
1
mer
Denis Burgarella (LAM) @ Salle Univers
Fév 1 @ 11 h 00 min
Séminaire
JWST, WFIRST and FLARE predicted number counts at 10 < z < 15: the case for a Wide-Field N+MIR Space Telescope & the FLARE ESA M5 project, Denis Burgarella (LAM)
We can read in the science case presented for several next generation telescope projects, sentences like « The First Light theme science goal is to find and understand these predicted first light objects ». This one was extracted from https://jwst.stsci.edu/science-planning/science-corner/the-end-of-the-dark-ages-first-l Using what we presently know about galaxies in the very high redshift universe to z ~ 10, we can start to predict what we can expect in the redshift range 10 < z < 15 and these first-light objects. In this talk, I will try to present the present status of these predictions from several recent papers. As one might expect, the density of these extreme redshift galaxies and their spectral characteristics make them difficult to detect. I will derive some constraints about what the characteristics of a telescope should be to detect a reasonable sample of galaxies at z > 10 to z ~ 15. In addition to the extreme universe study, FLARE will build a 5000 deg2 imaging survey and 40 deg2 spectrocopic survey of the Milky Way in the N/M-IR at sub-arcsec resolution. In conclusion, we propose a technically simple and realistic project with clear and unique objectives related to the extreme universe and to the local universe communities (applications for the Solar system also exist). No other project in operation or planned is able to address these questions in the same statistical way.
Fév
8
mer
Le modèle de la Galaxie de Besançon : développements récents et perspectives avec la mission Gaia, Annie Robin @ Univers 22
Fév 8 @ 11 h 00 min – 12 h 00 min
Séminaire

Avec l’arrivée des données complexes et multi-variées de la mission spatiale Gaia et des grands relevés complémentaires au sol, les outils d’interprétation que sont les modèles ont besoin d’être adaptés et renforcés. Le modèle de la Galaxie de Besançon est un modèle qui utilise la synthèse de populations stellaires pour tenter d’expliquer les observations de tous types (photométrie, spectroscopie, astrométrie) et dans un grand intervalle de longueur d’onde (de l’UV jusqu’à l’infrarouge moyen), en se basant sur des hypothèses réalistes de formation et d’évolution de la Galaxie. Il prend en compte les derniers modèles d’évolution stellaire, la matière interstellaire, la distribution de la matière noire. Je passerai en revue les derniers avancements dans le développement du modèle, les résultats récents en terme d’évolution de la Galaxie et les perspectives avec l’arrivée des données de la mission Gaia.

Séminaire Annie Robin @ Univers 22
Fév 8 @ 11 h 00 min – 12 h 00 min
Séminaire
Fév
15
mer
Séminaire Émeline Bolmont (CEA) @ Salle Univers
Fév 15 @ 11 h 00 min
Séminaire
Mar
22
mer
Interstellar medium and star formation in extremely metal-poor galaxies, Vianney Lebouteiller (CEA) @ Salle univers 21
Mar 22 @ 11 h 00 min
Séminaire
The interstellar medium (ISM) is a fundamental component of galaxies, participating in the complex network responsible for star formation and galaxy evolution. Star formation, which occurs in cold dense clouds subject to gravitational instabilities, is affected by dynamical feedback but thermal processes also play an essential role, especially in a primitive (metal-poor) ISM. The abundance of heavy elements in the ISM is therefore a crucial parameter, through the formation of dust particles, of molecular hydrogen, and of important gas-cooling species. These processes participate in the shielding from photodissociating UV photons and/or in controlling the thermal balance of the gas. The Nearby Universe includes galaxies with metallicities down to 3% of that of the Milky Way. This provides us with the opportunity of examining and understanding the impact of metallicity on the ISM properties, the star-formation process, and in general galaxy evolution, in conditions approaching those potentially found in a primordial environment. In this seminar, I will present recent results concerning dust and gas properties in a sample of extremely metal-poor galaxies.
Avr
12
mer
Séminaire Arnaud Pierres : Evolution of planets in self-gravitating circumbinary discs @ Salle Univers 22
Avr 12 @ 11 h 00 min
Séminaire

To date, ten circumbinary planets orbiting around a close main sequence binary have beed detected by the Kepler space mission. Most of these planets are located just outside the limit of dynamical stability, in a region where gravitational perturbations from the central binary make their in-situ formation very challenging. This suggests that circumbinary planets may have formed further out in the disc and moved to their current positions by disc-driven migration. In the context of this scenario, the orbital configuration of circumbinary planets is determined through the interaction with the circumbinary disc, which develops an inner cavity and becomes eccentric due to the interaction with the central binary. Understanding what physics shape the disc structure is therefore a crucial issue to explain the current orbital architecture of the Kepler circumbinary planets. To this aim, I will present the results of a recent study that investigates the impact of self-gravity on the evolution and structure of circumbinary discs, as well as the evolution of planets in these discs. I will also discuss the effect of disc warping that arises when the disc and orbital plane of the central binary are slightly misaligned.