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Lucky Puspitarini’s thesis defense

The 3D Distribution of Interstellar Gas and Dust in the Galaxy: Gaia-Related Preparatory Work
» Friday 17 October 2014

Directrice de thèse :

  • Rosine Lallement (GEPI - Observatoire de Paris)

Accurate and detailed three-dimensional (3D) maps of Galactic ISM are
still lacking. One way to obtain such 3D descriptions is to record a
large set of individual absorption or reddening measurements toward
target (background) stars located at various known distances and
directions. The inversion of these measurements using a tomographic
method can produce the spatial distribution of the ISM. Until recently
absorption data were very limited and distances to the target stars
lacking or uncertain, but the situation will greatly improve thanks to
current and future massive stellar surveys from ground, and to the Gaia
mission. Extracting interstellar (IS) absorption data from a large
number of stellar spectra requires new tools: we have developed
automated spectral analysis tools adapted to different IS tracers, such
as gaseous lines and diffuse interstellar bands (DIBs) as well as to
early- or late-type stars, thanks to synthetic stellar spectra based on
the known stellar parameters. We also developed a global analysis tool
to fit simultaneously multiple IS tracers, allowing to understand their
relationships and to derive their kinematic information at the same
time. I will show applications of the tools to several datasets
including Gaia-ESO Spectroscopic Survey (GES) spectra, and show the
potentiality of DIBs to trace the ISM in the Galaxy. I will finally
briefly show and comment the latest 3D map of the nearby ISM which reveal
nearby cloud complexes and cavities (or bubbles), and finally comment the
determination of the local bubble (LB) hot gas pressure owing to the
comparison with soft X-ray emission maps.