Results 31 to 40 of about 2,475,342 (218)
Sagittarius B1: A Patchwork of H ii Regions and Photodissociation Regions [PDF]
The Astrophysical Journal, 2021 Abstract Sgr B1 is a luminous H ii region in the Galactic center immediately next to the massive star-forming giant molecular cloud Sgr B2 and apparently connected to it from their similar radial velocities. In 2018 we showed from SOFIA FIFI-LS observations of the [O iii] 52 and 88 μm lines that there is no central exciting star cluster ...
Janet P. Simpson +4 more
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Carbon Chemistry in Photodissociation Regions [PDF]
Proceedings of the International Astronomical Union, 2005 We present recent results on the carbon chemistry in photodissociation regions. We show that carbon chains and rings (CCH, c-C$_3$H$_2$ and C$_4$H) are tightly spatially correlated with each other, and with the mid-infrared emission due to PAHs (7 and 15 $\mu$m), mapped by ISOCAM.
M. Gerin +8 more
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A Magnetically Supported Photodissociation Region in M17
The Astrophysical Journal, 2007 The southwestern (SW) part of the Galactic H II region M17 contains an obscured ionization front that is most easily seen at infrared and radio wavelengths. It is nearly edge-on, thus offering an excellent opportunity to study the way in which the gas changes from fully ionized to molecular as radiation from the ionizing stars penetrates into the gas ...
Pellegrini, E. W. +8 more
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Time-Dependent Photodissociation Regions [PDF]
The Astrophysical Journal, 1995 We present theoretical models of the time-dependent thermal and chemical structure of molecular gas suddenly exposed to far-ultraviolet (FUV) (6 eV less than hv less than 13.6 eV) radiation fields and the consequent time- dependent infrared emission of the gas. We focus on the response of molecular hydrogen for cloud densities ranging from n = 10(exp 3)
David Hollenbach, Antonella Natta
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The Astrophysical Journal Supplement Series, 2022 We present an efficient heating/cooling method coupled with chemistry and UV radiative transfer that can be applied to numerical simulations of the interstellar medium (ISM).
Jeong-Gyu Kim +3 more
doaj +1 more source
Photodissociation regions. I - Basic model. II - A model for the Orion photodissociation region
The Astrophysical Journal, 1985 A theoretical parameter study of the temperature and chemical structure of dense photodissociation regions and their resultant spectrum is presented. Models are discussed which are relevant not only to the dust and gas between molecular clouds and H II regions, but also apply to any neutral cloud illuminated by intense FUV fluxes.
A. G. G. M. Tielens, D. Hollenbach
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Ab Initio Study of Ground-state CS Photodissociation via Highly Excited Electronic States [PDF]
, 2019 Photodissociation by ultraviolet radiation is the key destruction pathway for CS in photon-dominated regions, such as diffuse clouds. However, the large uncertainties of photodissociation cross sections and rates of CS, resulting from a lack of both ...
Jackson, William M +6 more
core +1 more source
The Astrophysical Journal, 2023 Photodissociation regions (PDRs) illuminated by high temperature ( T > 10 ^4 K) radiation fields display characteristic optical to midinfrared spectral features: emission bands that cluster around the blue limits of hydrogen series, an extended red ...
Frédéric Zagury
doaj +1 more source
On Metal Carbonyl Compounds in Catalytic Methanol Synthesis: Detection, Consequences, and Removal
Chemie Ingenieur Technik, EarlyView.Deactivation of Cu/ZnO/Al2O3 catalysts by metal carbonyl compounds in the feed gas is a critical problem in catalytic methanol synthesis. We utilize PTR–MS to identify potential chemical sources, detect contamination in an in‐house CO gas line, and validate filter methods for removing these catalyst poisons before synthesis.
Florian Stappert +4 more
wiley +1 more source
Photodissociation Regions in Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1993 The photodissociation rate of H2 molecules by UV photons from PN central stars is generally several orders of magnitude larger than the rate produced by the average interstellar field (Sternberg 1988, Escalante et al. 1991). Thus, in neutral envelopes of PN's, H2 molecules are destroyed quickly, and a photodissociation region forms around ionization ...
V. Escalante, A. Góngora-T
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