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Theses

Etalonnage de Herschel/HIFI : approche système et expérimentale d'un instrument scientifique spatial. Etude observationnelle de coeurs denses galactiques.

Abstract : The calibration of a remote-sensing instrument for the observation of the Earth or of the Cosmos is a key to the highest scientific return from the experiment.
In the first part of this thesis, we initiate the preparation of the calibration tools and methods for the submillimetre spectrometer HIFI on board the Herschel satellite. The first aspect concentrates on the data calibration and their convertion into a physical scale. We first collect the requirements of the in-flight calibration and identify the primary and secondary calibrators. We then build a list of potential candidates, complemented by a ground-based preparatory observation campaign. We study the current internal calibration scheme based on two internal loads, and present a first error budget on the HIFI measurements. We show that this approach is {\it a priori} not adapted to the space conditions, and we give the preliminary elements of a best-suited calibration technique. The second point of this calibration work focusses on the instrument calibration in itself. We analyse the needs of the laboratory measurement campaign of the first HIFI prototype and propose an original system allowing to calibrate various instrumental parameters on the ground. We also show the importance of an instrumental modelling work, and present a description of the standing wave systems expected to affect the HIFI data.
The second part of this thesis is dedicated to the study of dense galactic cores detected in the mid-infrared by the ISO satellite. We show that these objets belong to a new population of massive (M > 1000 solar masses) and cold (8 < T < 25 K) condensations associated to giant molecular clouds. Our analysis indicates visible extinction in excess of 50, and suggests that depletion onto grains affects most of the molecular species. We also show that these objets are fragmented, and that they are very likely future, if not already initiated, progenitor sites of high mass stars.
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https://tel.archives-ouvertes.fr/tel-00001957
Contributor : David Teyssier <>
Submitted on : Monday, November 11, 2002 - 5:50:33 PM
Last modification on : Thursday, December 10, 2020 - 12:36:52 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 6:35:19 PM

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  • HAL Id : tel-00001957, version 1

Citation

David Teyssier. Etalonnage de Herschel/HIFI : approche système et expérimentale d'un instrument scientifique spatial. Etude observationnelle de coeurs denses galactiques.. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00001957⟩

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