Calendar

Nov
27
mar
Thibault Cavalié — Millimeter/submillimeter observations and modeling of chemistry and dynamics in Solar System Giant Planet atmospheres @ Univers 21
Nov 27 @ 11 h 00 min – 12 h 00 min
Séminaire

Better understanding Solar System Giant Planet formation and evolution requires in situ measurements, remote sensing observations either with telescopes or planetary missions, and modeling. While more and more exoplanets are discovered every day and while we will better characterize them with new observatories like JWST, the planets of the Solar System remain our local laboratory for studying formation and evolution of such bodies. The (sub)millimeter domain, owing to the very high spectral resolution of the heterodyne technique and to the ever increasing spatial resolution and sensitivity of new observatories like ALMA, is suitable for determining planetary atmospheric composition and dynamics when coupled with appropriate radiative transfer, photochemical or thermochemical modeling.

 

In this seminar, I will summarize 10 years of observations and modeling of the Solar System Giant Planets I have been involved in.

I will first show that thermochemical modeling of the deep tropospheres of the Giant Planets can help us establish their deep composition to constrain their formation processes. The next step is the participation in an atmospheric probe proposal for the Ice Giants, and the development of its mass spectrometer, in preparation for a NASA-ESA joint flagship mission to these distant worlds.

I will also show how observations and time-dependent 1D or 2D photochemical modeling have enabled us to improve our understanding of how the composition and chemistry in the stratospheres of the Giant Planets are altered by seasons and external sources. With ALMA, it is now even possible to directly measure winds in the stratospheres of the Giant Planets to constrain their stratospheric circulation.

Finally, I will present how the Submillimetre Wave Instrument of the Jupiter Icy Moons Explorer (JUICE) mission will allow us, in about a decade from now, to monitor Jupiter’s atmosphere, both in terms of chemistry and dynamics, and with spectral and spatial resolutions and temporal coverage never achieved before.

Déc
5
mer
Andréa Bertoldi — MIGA and Gravitational Wave detection at low frequency with Atom Interferometry @ Univers 21
Déc 5 @ 11 h 00 min – 12 h 00 min
Séminaire

The recent detection of Gravitational Waves (GWs) by LIGO and VIRGO opened a new observation window on the Universe and started the era of Gravitational Astronomy. Atom interferometry has been proposed to extend the detection bandwidth of GW detectors in the infrasound band (10 mHz – 10 Hz) [1], where actual ground based detectors are limited by low frequency gravity noise. Adopting as probes arrays of atomic ensembles in free fall, and tracking their motion on geodesics with atom interferometry allows the suppression of Newtonian Noise [2], enables low frequency sensitivity, and opens the way toward the realization of low frequency GW detectors on Earth. I will report on the « Matter wave – laser based Interferometer Gravitation Antenna » (MIGA) project [3], whose target is to build an atom interferometry based demonstrator for GW detection in the underground environment of LSBB (Rustrel, France).

[1] S Dimopoulos et al, Phys Lett B 678, 37 (2009)
[2] W Chaibi et al, Phys Rev D 93 (2), 021101 (2009)
[3] B Canuel, A. Bertoldi et al, Sci. Rep. 8, 14064 (2018)

Déc
18
mar
Marcel Agueros — séminaire LAB @ Univers 21
Déc 18 @ 11 h 00 min – 12 h 00 min
Séminaire

TBD

Jan
16
mer
Nathalie Ysard : Séminaire LAB @ Univers 21
Jan 16 @ 11 h 00 min – 12 h 00 min
Séminaire

TND

Jan
23
mer
Benoit Commercon : séminaire LAB @ Univers 21
Jan 23 @ 11 h 00 min – 12 h 00 min
Séminaire

TBD

Jan
29
mar
Javier Olivares — Bayesian Modeling @ Univers
Jan 29 @ 11 h 00 min – 12 h 00 min
Séminaire

TBD

Jan
31
jeu
Laurent Chemin — The orbital anisotropy of velocity in spiral and irregular galaxies @ Univers 21
Jan 31 @ 12 h 00 min – 13 h 00 min
Séminaire

TBD

Fév
6
mer
Panayotis Lavvas — Séminaire LAB @ Univers 21
Fév 6 @ 12 h 00 min – 13 h 00 min
Séminaire

TBD

Fév
13
mer
Cécile Engrand: The composition of interplanetary and cometary dust @ Univers 21
Fév 13 @ 11 h 00 min – 12 h 00 min
Séminaire

Small bodies have escaped planetary accretion and have best preserved the composition of the matter initially present in the solar nebula. Cosmic dust originates from these small bodies, asteroids and comets. Interplanetary and cometary dust are collected on Earth in places with a low accumulation rate of terrestrial dust, like the polar caps or the stratosphere. Interplanetary dust particles (IDPs) have been collected in the stratosphere by NASA for a few decades. A fraction of IDPs (at least) are proposed to be of cometary origin. Cosmic dust from the polar caps are larger than IDPs and are called micrometeorites. We collect micrometeorite at the Concordia Antarctic station at Dome C since 2000. The Concordia collection contains very pristine samples, including particles that are dominated by organic matter and that are very probably cometary. Spatial missions like Stardust (NASA), Hayabusa (JAXA) and Rosetta (ESA) also gave access to the structure and composition of asteroidal and cometary dust. Stardust brought back dust particles from comet 81P/Wild 2, but the collection occurred at high relative velocity (6 km/s) and the samples were altered during the collection. The Rosetta mission collected dust particles from comet 67P/Churyumov-Gerasimenko at much lower velocity (1-10 m/s), but the analyses had to be performed in situ onboard the Rosetta orbiter by the dust instruments (GIADA, COSIMA, MIDAS). The Hayabusa mission returned samples from asteroid Itokawa, which is an asteroid related to ordinary chondrites. At least two future spatial missions are bound to bring back samples from carbonaceous asteroids: Hayabusa 2 (JAXA, asteroid Ryugu) et OSIRIS-REx (NASA, asteroid Bennu). The CAESAR mission is also currently under study to bring back a sample from comet 67P/Churyumov-Gerasimenko.
The presentation will summarize the present knowledge on the composition of interplanetary and cometary dust, based on the results of laboratory analysis of dust particles collected on Earth, and of spatial missions.