| Description |
As a GT Key Program we propose to perform full HIFI and PACS line surveys of 5
sources in the giant molecular clouds Orion and Sagittarius B2. These
extraordinary star-forming regions contain the best studied examples of
physical and chemical processes prevalent in the interstellar medium, including
gravitational compression, thermal and turbulent pressure support,
photodissociation, gas and grain chemistry in dense and diffuse quiescent gas,
and shocks. With high excitation, rich chemistry, and large molecular column they
give the highest chance for new detections in a sensitive search for new
molecules. Line surveys of sources (Orion KL, Orion S, Orion Bar, Sgr B2 N+M)
defined by these phenomena form the backbone of this proposed program.
Herschel offers unprecedented sensitivity and relative calibration accuracy,
as well as continuous spectral coverage across the gaps imposed by the
atmosphere, opening up a largely unexplored wavelength regime to high
resolution spectroscopy. These data will take line surveys to a new level and
we will use them to comprehensively characterize the physics (density,
thermal balance, kinematics, radiation field) and chemistry (chemical assay,
ionization, deuterium fractionation, water ortho/para ratio) of star-forming
molecular gas in a manner not previously possible. The opening of this
spectral range is also an opportunity to detect the bending transitions of
carbon chains and polycyclic aromatic hydrocarbons, along with the
rotational transitions of complex organics.
Given that these sources have the richest emission spectra seen for star-forming regions in the Galaxy, we anticipate that the proposed observations will define the sub-millimeter/far infrared region of the spectrum and that these data will form a lasting Herschel legacy. |
| Publication |
Bottlenecks to interstellar sulfur chemistry. Sulfur-bearing hydrides in UV-illuminated gas and grains . Goicoechea J. R. et al. . Astronomy and Astrophysics . null . null . 2021A&A...647A..10G ,
Exploring the Origins of Earth’s Nitrogen: Astronomical Observations of Nitrogen-bearing Organics in Protostellar Environments . Rice Thomas S. et al. . The Astrophysical Journal, Volume 866, Issue 2, article id. 156, 16 pp. (2018). . 866 . 10.3847\/1538-4357\/aadfdb . 2018ApJ...866..156R ,
Herschel/HIFI spectral line survey of the Orion Bar. Temperature and density differentiation near the PDR surface . Nagy Z. et al. . Astronomy & Astrophysics, Volume 599, id.A22, 24 pp. . 599 . 10.1051\/0004-6361\/201628916 . 2017A&A...599A..22N ,
Spatially extended OH+ emission from the Orion Bar and Ridge . van der Tak F. F. S. et al. . Astronomy & Astrophysics, Volume 560, id.A95, 10 pp. . 560 . 10.1051\/0004-6361\/201322164 . 2013A&A...560A..95V ,
Interstellar bromine abundance is consistent with cometary ices from Rosetta . Ligterink N. F. W. et al. . Astronomy & Astrophysics, Volume 614, id.A112, 8 pp. . 614 . 10.1051\/0004-6361\/201732325 . 2018A&A...614A.112L ,
Structure of photodissociation fronts in star-forming regions revealed by Herschel observations of high-J CO emission lines . Joblin C. et al. . Astronomy & Astrophysics, Volume 615, id.A129, 20 pp. . 615 . 10.1051\/0004-6361\/201832611 . 2018A&A...615A.129J ,
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