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mars 2019
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NISP team (LAM) - NISP/EUCLID technical presentation and status.

Vendredi 1er mars 11:00-12:00

The NISP (Near Infrared Spectrometer and Photometer) is one of the two instruments to fly on the ESA Euclid spacecraft mid 2022. It operates in the near-IR spectral region (900-2000nm) as a photometer and spectrometer. The instrument is composed of :

  • a cold (135K) optomechanical subsystem consisting of a Silicon carbide structure, an optical assembly, a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system
  • a detection system based on a mosaic of 16 H2RG with their front-end readout electronic.
  • a warm electronic system (280K) composed of a data processing / detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data

We will present :

  • the Euclid spacecraft
  • the NISP final architecture, the different subsystems and the main performances
  • the NISP development plan, the test plan and the schedule
  • the NISP EM and FM integration

Martin Crocce (IEEC-CSIC) - Accelerated Cosmic Expansion and the Dark Energy Survey

Vendredi 8 mars 11:00-12:00

The striking discovery that the Cosmic expansion is not slowing down but accelerating has turned into one of the puzzles in Cosmology sparking large observational campaigns to map the Large Scale Structure and geometry of the Universe across cosmic time. I will briefly review this effort and then discuss The Dark Energy Survey (DES), a state-of-the-art large-scale galaxy survey designed to understand such acceleration by mapping 5000 deg2 measuring the positions and shapes for 300 million galaxies up to redshift 1, the light-curves of several thousand supernovae, and the masses of tens of thousands of galaxy clusters. I will present the latest cosmological results from the first year of observations, in particular those related to the combination of large-scale structure and weak gravitational lensing, how they compare with those from other datasets, and what to expect in the near future.

Sebastian Kamann (Liverpool John Moores University) - Dynamical clues to the formation of star clusters

Vendredi 15 mars 11:00-12:00

The star cluster population of the Milky Way provides a unique window to study the formation history of our Galaxy. The conditions of the epochs when the Milky Way built up most of its stellar mass are preserved in the star clusters we observe to date. However, the physics governing the formation of star clusters are still not entirely understood. For example, ancient globular clusters show subtle differences in the chemical compositions of their stars which appear to be absent in the clusters forming today. Does this suggest that cluster formation varies with mass or cosmic age ? In my presentation, I want to show how we can use the stellar dynamics of the clusters to answer such questions. Thanks to satellites such as Hubble or Gaia and powerful spectrographs we can nowadays study the motions of representative samples of stars in clusters of all ages. Using data from the MUSE spectrograph, we could already show that rotation played a crucial role in the formation of globular clusters and that they harbour larger populations of black holes than previously thought. We are further using the data to search for differences in the kinematics of their stellar populations. If detected, such differences put stringent constraints on the mechanisms that led to the formation of multiple populations in globular clusters.

Coralie Neiner (LESIA, Observatoire de Meudon, France) - Space UV spectropolarimetry

Vendredi 22 mars 11:00-12:00

In many domains of astrophysics, the study of magnetism and polarized light has become a new and essential tool. This has however never been done in the UV as it requires to go into space. I will present recent R&D work on UV polarimeters and current studies of space mission projects equipped with a high-resolution UV spectropolarimeter, such as Pollux for LUVOIR, Arago, or Lodestar.

David Ehrenreich (U. Geneva) - Exoplanetary atmospheres at high spectral resolution

Vendredi 29 mars 11:00-12:00

Observing transits of exoplanets with the Hubble Space Telescope in the ultraviolet has revealed spectacular atmospheric escape of strongly irradiated gas giants. This atmospheric photo-evaporation could explain the dearth of intermediate-mass planets close to their stars, as well as the valley separating two populations of super-Earths. The deposition of a tremendous amount of high-energy irradiation in the outer atmospheric layers of exoplanets should also impact their physical and chemical properties. I will review recent observations obtained wh ground-based, high-resolution spectrographs, that unveil the extreme conditions reigning in the upper atmospheres of exoplanets.

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