Results 81 to 90 of about 49,075 (253)

Abundance Ratios of OH/CO and HCO+/CO as Probes of the Cosmic-Ray Ionization Rate in Diffuse Clouds

open access: yesThe Astrophysical Journal, 2023
The cosmic-ray ionization rate (CRIR, ζ _2 ) is one of the key parameters controlling the formation and destruction of various molecules in molecular clouds. However, the current most commonly used CRIR tracers, such as ${{\rm{H}}}_{3}^{+}$ , OH ^+ , and
Gan Luo   +8 more
doaj   +1 more source

Astrochemistry: overview and challenges [PDF]

open access: yes, 2017
This paper provides a brief overview of the journey of molecules through the Cosmos, from local diffuse interstellar clouds and PDRs to distant galaxies, and from cold dark clouds to hot star-forming cores, protoplanetary disks, planetesimals and ...
van Dishoeck, Ewine F.
core   +3 more sources

Adsorption of Helium on Cationic or Anionic Tetracene and Pentacene

open access: yesSmall Structures, Volume 7, Issue 1, January 2026.
How does the arrangement of helium atoms that are adsorbed on tetracene or pentacene ions change with increasing coverage? When does the adsorption layer change from 1D to 2D, and to 3D? Is the transition abrupt? Are the helium atoms localized? Is the arrangement the same for cations and anions? What changes as the acene grows in length?
Miriam Kappe   +6 more
wiley   +1 more source

Turbulent Diffuse Molecular Media with Nonideal Magnetohydrodynamics and Consistent Thermochemistry: Numerical Simulations and Dynamic Characteristics

open access: yesThe Astrophysical Journal
Turbulent diffuse molecular clouds can exhibit complicated morphologies caused by the interactions among radiation, chemistry, fluids, and fields.
Nannan Yue   +4 more
doaj   +1 more source

Mapping Galactic Dust Emission and Extinction with H I, H II, and H2

open access: yesThe Astrophysical Journal
Neutral hydrogen (H i ) emission closely traces the dust column density at high Galactic latitudes and is thus a powerful tool for predicting dust extinction. However, the relation between H i column density N _HI and high-latitude dust emission observed
Yun-Ting Cheng   +3 more
doaj   +1 more source

Surveys of the Milky Way and Magellanic System in the λ21-cm line of atomic hydrogen

open access: yesEPJ Web of Conferences, 2012
In the next three years, surveys of the Northern and Southern skies using focal plane arrays on aperture synthesis radio telescopes will lead to a breakthrough in our knowledge of the warm and cool atomic phases of the interstellar medium and their ...
Dickey J.M.
doaj   +1 more source

Sodium depletion within diffuse interstellar clouds

open access: yesThe Astrophysical Journal, 1975
Having derived estimates of the densities and radiation fields within several interstellar clouds from the observed populations of the H$sub 2$ rotational levels, we can estimate the amount of sodium and calcium depletion within different clouds.
openaire   +1 more source

High-Resolution Images of Diffuse Neutral Clouds in the Milky Way. I. Observations, Imaging, and Basic Cloud Properties

open access: yes, 2015
A set of diffuse interstellar clouds in the inner Galaxy within a few hundred pc of the Galactic plane has been observed at an angular resolution of ~1 arcmin combining data from the NRAO Green Bank Telescope and the Very Large Array.
Dickey, John M.   +3 more
core   +2 more sources

A Reanalysis of the Carbon Abundance in the Translucent Cloud toward HD 24534 [PDF]

open access: yes, 1998
We have reanalyzed the Goddard High Resolution Spectrograph data set presented by Snow et al. which contains the interstellar intersystem C II] 2325A line through the translucent cloud toward HD 24534 (X Persei). In contrast to the results of Snow et al.,
David M. Meyer   +4 more
core   +2 more sources

Kinetics and Thermodynamics of Tautomerization Reactions of 1,1‐ and 1,2‐Ethenediols

open access: yesInternational Journal of Chemical Kinetics, Volume 57, Issue 12, Page 687-696, December 2025.
ABSTRACT Tautomerism is a common phenomenon amongst organic molecules with easily interconvertible isomers, which can impact drug action and toxicity. Here we are interested in the enols of carboxylic acids, which are known to be much less stable than their acid counterparts.
Judith Würmel, John M. Simmie
wiley   +1 more source

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