Diffuse Atomic and Molecular Clouds

By T. Snow, B. McCall. 2006

451 citations recorded by the source corpus.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/4289f44d6efb5e947da6237d7f1f6039bbf6ad1a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

In Spectroscopy

Citations in the corpus

Turbulent molecular clouds (2012, background): “…generally agreed that it is a low density medium (nH a few 10 3 cm−3), weakly shielded from the interstellar radiation field (ISRF) (AV a few mag), therefore comprising the diffuse atomic (nH ∼ 50 cm−3), diffuse molecular and translucent media, following the terminology of Snow & McCall (2006).”
Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions (2010, background): “The physical conditions of the five benchmarking cases are summarized in Table 1, (see also Snow & McCall, 2006; Hassel et al., 2008).”
H$_2$ formation on interstellar dust grains: the viewpoints of theory, experiments, models and observations (2017, background): “The density ranges from 10 to 100 cm −3 and the gas and dust temperatures are around 30–100 K and 15– 20 K respectively ( Snow and McCall, 2006 , for a review).”
2018 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules (2018, background): “These environments are characterized by low total number densities (nH ∼10 – 104 cm−3), cool, but not cold kinetic temperatures (Tk 100 K), and enhanced radiation environments over those seen in ‘standard’ dense molecular clouds (for a detailed review, see Snow & McCall 2006).”
CO-dark gas and molecular filaments in Milky Way-type galaxies (2014, background): “Absorption line measurements probing the ends of these structures would probably characterize them as diffuse molecular clouds (Snow & McCall 2006), while their central regions would be visible in CO emission and would be classified as dense molecular clouds, even though in reality both regions are…”
INVESTIGATING THE COSMIC-RAY IONIZATION RATE IN THE GALACTIC DIFFUSE INTERSTELLAR MEDIUM THROUGH OBSERVATIONS OF H+3 (2011, background): “…by CO is about 2 orders of magnitude slower than by electrons (see Table 3), the density of dense clouds is about 2–3 orders of magnitude larger than diffuse clouds (Snow & McCall 2006), and the fractional abundance of electrons in diffuse clouds should be about equal to that of CO in dense clouds.”
The Nine Lives of Cosmic Rays in Galaxies (2015, background): “A neutral region where thermal UV photons dominate the ionization, chemistry, and thermal state of the gas is called a photon-dominated region (PDR), which includes by definition the so-called diffuse and translucent molecular clouds (Snow & McCall 2006).”
Physical Processes in the Interstellar Medium (2014, background): “However, as tform ∝ n−1, the formation time can be significantly longer than the dynamical time in lower density clouds, such as the diffuse H2 clouds observed in UV absorption line studies (Snow and McCall 2006), and it is therefore unclear whether the H2 content of these clouds has yet reached equ”
What makes a planet habitable? (2009, background): “The interstellar medium (ISM) hosts an active carbon chemistry that is strongly influenced by environmental conditions such as density, temperature and radiation conditions (Wooden et al. 2004; Snow and McCall 2006).”
Ultraviolet Survey of CO and H2 in Diffuse Molecular Clouds: The Reflection of Two Photochemistry Regimes in Abundance Relationships (2008, methodology): “Since these clouds can be small ( 0.6 pc) with n ≥ 100 cm−3 and Tspin 50 K, the physical conditions in them are very similar to the clouds studied here, or in other words, they correspond to the intermediate category of diffuse molecular clouds (Snow & McCall 2006).”
ROTATIONAL QUENCHING OF CO DUE TO H2 COLLISIONS (2010, background): “CO is observed in diffuse clouds in absorption in the ultraviolet (UV) and visible and in emission at infrared (IR) wavelengths (Snow & McCall 2006), revealing the physical and chemical complexity along these lines of sight.”
WATER, O2, AND ICE IN MOLECULAR CLOUDS (2008, background): “…some cases, CO is frozen on grains in very high AV regions at cloud centers; see, for example, Bergin & Tafalla (2007) for a review of the observations. in absorption, are characterized by G0 ∼ 1–10, n ∼ 100 cm−3, and AV ∼ 1–5 (these are sometimes called “translucent clouds”; Snow & McCall 2006).”