Galaxies, dust and stars

My career in astrophysical research really began with a master's internship, during which I observed bipolar flows in the CO molecule using the small POM telescope. For the DEA I continued in the millimeter range. During my PhD thesis, I was interested both in understanding the relationship between the IRAS emission from the Magellanic Clouds, two of our dwarf satellite galaxies, and the age of their stellar populations, and in highlighting variations in the properties of the interstellar medium of galaxies as a function of their morphological type. During this period, 1988-1991, it was hard not to notice two things happening around me: the construction of ISOCAM and CAMIRAS, the first of a long generation of 10 μm ground-based cameras built at the Astrophysics Department. After my thesis, I became involved full-time in the management of an observatory of international stature. As astronomer-support, I was in charge of the 10 μm camera, first in its SAp version, then in its Lyon version. In the case of a visiting instrument like this one, my role was less to assist astronomers in their observations than to manage the logistics of installing and powering the instrument. In May 1993, I joined the ISOCAM team. At that time, the SAp was just about to deliver the flight model of the camera, and so I accompanied the team in the transition from the design phase to the characterization phase, and then to the transformation into a 'public' instrument. I took part in writing the ISOCAM user manual, testing the observation creation program, and defining the analysis software. On the scientific side, I helped finalize the guaranteed time programs for the galaxies of the Local Universe. These preparatory activities came to an end on November 17, 1995, with the launch of ISO. During the 28 months of ISO's operation, I divided my time between my research, which will be discussed in most of this document, and accompanying the instrument. In early 1995, CNES decided to set up a French ISO Center to assist French scientists in their ISO operations. This center mission was to provide visitors with the tools and expertise needed to prepare, build and operate the ISO satellite. I coordinated the SAp's participation in this center, taking charge of ISOCAM and ISOPHT activities (see chapter 7). This center remained active until 2001, and it was through some of its visitors that I became involved in problems as varied as evolved stars, supernovae, H II regions and elliptical galaxies. At the same time, I was involved in the development of ISOCAM data analysis systems. At the end of operations, I also spent 2 months at the data reception center in Vilspa, both to relieve Pascal Gallais, who had spent over a year there, and to participate even more directly in the life of the satellite. I wasn't disappointed, as during my stay I was treated to the most violent solar flare recorded in the satellite's lifetime. ISOCAM was blinded for a few days, but recovered without a hitch. Scientifically, my horizon at the time was between 5 and 18 μm, ISOCAM's bandwidth. I devoted myself to programs studying spiral galaxies and their star-forming regions. Towards the end of ISO's life, in the extra time granted by the cryostat, compact blue galaxies reappeared, with Suzanne Madden's arrival at SAp, and so was born what is today my main subject of study and amazement: buried stellar super-clusters. With them, my horizons broadened, first to the far infrared, then to optics on the one hand and sub-millimeters on the other. At the same time as ISO was winding down, SAp's involvement in the Herschel project was taking shape. Since then, it has grown considerably, playing a major role in both spectro-imagers. Herschel is a logical sequel to ISO, so it's only natural that I should be involved, as Scientific Manager for SAp, Scientific Associate for one of the instruments, SPIRE, and Co-Investigator for the other, PACS. (author)