Results 111 to 120 of about 25,001 (219)
A search for interstellar H2O(+) in diffuse clouds
The Astrophysical Journal, 1984 Searches for H2O(+) toward HD 187982, Zeta Oph, O micron Per, and Zeta Per have yielded significant upper limits for H2O(+) when compared with existing models for similar lines of sight. Using available oscillator strength data, the column density for HD 187982, for example, cannot exceed 3 x 10 to the 12th per sq cm H2O(+) molecules.
Wm. H. Smith +2 more
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Observations of CO emission from diffuse interstellar clouds
The Astrophysical Journal, 1976 We report measurements of, and upper limits for, millimeter-wavelength CO emission from interstellar clouds which have previously been studied via optical absorption lines. Along with CO measurements made by the Copernicus satellite, the results can be used to place constraints on models for interstellar chemistry.
G. R. Knapp, M. Jura
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The Spectral Energy Distribution of Self-gravitating Interstellar Clouds I. Spheres
, 2007 We derive the spectral energy distribution (SED) of dusty, isothermal, self gravitating, stable and spherical clouds externally heated by the ambient interstellar radiation field.
Bernard J. P. +17 more
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Mapping the Cosmic-Ray Ionization Rate in the Local Galaxy with
The Astrophysical JournalChemistry in diffuse molecular clouds relies primarily on rapid ion-molecule reactions. Formation of the initial ions, H ^+ and H ${}_{2}^{+}$ , is dominated by cosmic-ray ionization of H and H _2 , making the cosmic-ray ionization rate (denoted ζ (X ...
Nick Indriolo +8 more
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UniverseGalactic cosmic rays (GCRs), composed of protons and atomic nuclei, are accelerated in sources such as supernova remnants and pulsar wind nebulae, reaching energies up to the PeV range.
Luan Torres, Luiz Augusto Stuani Pereira
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Optical and ultraviolet observations of diffuse interstellar clouds [PDF]
Symposium - International Astronomical Union, 1997 Absorption-line studies of diffuse interstellar clouds have recently been invigorated at ultraviolet wavelengths with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope and at optical wavelengths with efficient high resolution spectrographs and CCD detectors.
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Molecular Hydrogen Formation via Vibrational Excitation of Partially Superhydrogenated Pyrenes
The Astrophysical JournalWhile polycyclic aromatic hydrocarbons (PAHs) are now accepted to be abundant in interstellar space, the abundance and influence of superhydrogenated PAHs (HPAHs) in the interstellar medium (ISM) are still under investigation.
Frederik Doktor S. Simonsen +6 more
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Formaldehyde production in diffuse interstellar clouds [PDF]
Monthly Notices of the Royal Astronomical Society, 1979 Millar, TJ, Duley, W.W., Williams, D.A.
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Calcium abundance variations in diffuse interstellar clouds
The Astrophysical Journal, 1976 Observations are discussed which show that the Na I/H2 column-density ratio is relatively constant among different clouds where H2 is optically thin, but the Na I/Ca II column-density ratio varies. This implies that the gas-phase abundance of calcium is variable. It is proposed that the wide variation in the gas-phase calcium abundance can be explained
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On the CH(+) ion in diffuse interstellar clouds
The Astrophysical Journal, 1986 Un balayage de 65 lignes de visee dans la Voie Lactee Sud dans la raie interstellaire de CH + a 4232 A a permis 30 detections. La densite de colonne de CH + N(CH + ) est bien correlee avec H 2 excite par rotation detecte par des balayages effectues avec Copernicus.
D. L. Lambert, A. C. Danks
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