| Description |
The understanding of the processes governing the formation of interstellar
clouds and subsequent star formation is key for our understanding of how
galaxies evolve in our Universe. Special interest is given to the study of
low-metallicity interstellar matter as it is thought to be representative
of the environment where stars formed at earlier cosmological time. Unique
targets for this study are the Large and Small Magellanic clouds, which
are the closest low-metallicity star forming systems. We propose deep,
velocity--resolved observations of the [CII] 158 um, [CI] 609um, and [CI]
370um lines towards 54 representative positions in the Large and Small
Magellanic clouds with the HIFI instrument on board of Herschel. These
will be combined with our MAGMA CO data to obtain a complete inventory of
carbon in the Magellanic clouds. We selected positions to represent
different ISM environments, based on whether they show: a) HI peaks with
little or no 160um dust emission and no CO, b) HI and 160um peaks but
still no CO, and c) CO peaks. We also include a sample of lines-of--sight
observed by FUSE which have known H2 column densities, which will allow
us to calibrate our use of [CII] as a tracer of HI and H2 column
densities. Our sample therefore includes clouds in different stages of
evolution going from diffuse atomic to diffuse molecular and to dense
molecular clouds. We will use an excitation/radiative transfer code and a
PDR model to derive the physical conditions of the line-emitting gas. Our
observations have the potential to discover large quantities of dark H2
gas traced by [CII] and perhaps [CI] emission, as recently observed in
[CII] emission in the galactic plane (Langer et al. 2010 and Velusamy et
al. 2010). |
| Publication |
Characterizing the Transition from Diffuse Atomic to Dense Molecular Clouds in the Magellanic Clouds with [C II], [C I], and CO . Pineda Jorge L. et al. . The Astrophysical Journal, Volume 839, Issue 2, article id. 107, 31 pp. (2017). . 839 . 10.3847\/1538-4357\/aa683a . 2017ApJ...839..107P ,
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