|First steps toward star formation: unveiling the atomic to molecular transition in the diffuse interstellar medium
|We propose to map molecular material that is forming in the diffuse insterstellar gas, exploiting the unique capabilities of PACS and SPIRE: large area mapping at high angular resolution, sensitivity, and wavelength coverage spanning the peak of the dust spectral energy distribution. The main scientific goal is to discover the physical conditions in cirrus clouds that lead to the formation of the seeds of molecular clouds. Molecular hydrogen formation is fundamental to understanding the structure of molecular clouds and the core mass function (CMF) in the framework of the turbulent, magnetized and thermally bi-stable interstellar medium. Our strategy is to map two regions at high Galactic latitude with PACS and SPIRE and use the dust opacity deduced from Herschel data to map the total column density of matter. Then using our high resolution 21-cm data for these fields, the atomic-correlated contribution can be removed, leaving a map dominated by dust in the molecular gas. Statistical properties of the molecular structures will be related to the properties of interstellar turbulence, thermal instability, and CMF seen in molecular clouds. The H I data are essential to this project, not only to uncover the molecular gas but also to probe the dynamical conditions in which the molecular gas has formed. Both fields are part of a large project of H I observations of high Galactic latitude fields. The Spider field, a faint cirrus cloud with highly filamentary structure, is representative of the formation of H2 in dynamical conditions dominated by interstellar turbulence, with an average amount of molecular gas for diffuse clouds (estimated at about 15-20%). The Draco nebula, the archetype of interstellar matter re-entering the local interstellar medium after being expelled into the halo via the Galactic fountain, has a strikingly clumpy structure induced by its bulk motion with respect to the local ISM. There is ...a wide range of conditions to be modeled, including patchy CO emission.
|Quantifying the cool ISM in radio AGNs: evidence for late-time retriggering by galaxy mergers and interactions . Bernhard E. et al. . Monthly Notices of the Royal Astronomical Society . null . null . 2022MNRAS.512...86B ,
Search for candidate strongly lensed dusty galaxies in the Planck satellite catalogues . Trombetti T. et al. . Astronomy and Astrophysics . null . null . 2021A&A...653A.151T ,
Structure formation in a colliding flow: The Herschel view of the Draco nebula . Miville-Deschênes M.-A. et al. . Astronomy & Astrophysics, Volume 599, id.A109, 15 pp. . 599 . 10.1051/0004-6361/201628289 . 2017A&A...599A.109M ,
Optical and UV surface brightness of translucent dark nebulae. Dust albedo, radiation field, and fluorescence emission by H2 . Mattila K. et al. . Astronomy & Astrophysics, Volume 617, id.A42, 29 pp. . 617 . 10.1051/0004-6361/201833196 . 2018A&A...617A..42M ,
Beyond Simple AGN Unification with Chandra-observed 3CRR Sources at 0.5 &lt; z &lt; 1 . Kuraszkiewicz Joanna et al. . The Astrophysical Journal . null . null . 2021ApJ...913..134K ,
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2012, OT1_mmiville_2, SPG v14.2.0. https://doi.org/10.5270/esa-a2h0ing