Results 81 to 90 of about 547 (181)
Silicate Extinction Profile Based on the Stellar Spectrum by Spitzer/IRS
The Astrophysical JournalThe 9.7 and 18 μ m interstellar spectral features, arising from the Si–O stretching and O–Si–O bending modes of amorphous silicate dust, are the strongest extinction features in the infrared.
Zhenzhen Shao, Biwei Jiang
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Interstellar shocks and molecular CH/+/ in diffuse clouds
The Astrophysical Journal, 1980 The influence of shocks on the abundances of molecules in diffuse interstellar clouds is investigated with special emphasis on molecular CH/sup +/. Idealized shocks with plausible parameters are found to produce column densities for CH/sup +/ in the hot, postshock gas which are comparable with measured values in interstellar clouds (up to about 10/sup ...
M. Elitzur, W. D. Watson
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Diffuse interstellar medium and the formation of molecular clouds [PDF]
, 2009 (Abridged) The formation of molecular clouds (MCs) from the diffuse interstellar gas appears to be a necessary step for star formation, as young stars invariably occur within them. However, the mechanisms controlling the formation of MCs remain controversial.
Hennebelle, P. +2 more
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Unresolved velocity structure in diffuse interstellar clouds
The Astrophysical Journal, 1988 Recent high-resolution observations of interstellar absorption lines of CH and CN toward Zeta Oph obtained by Crane et al. (1986), and Palazzi et al. (1988), exhibit line widths that suggest thermal line broadening at high temperature, T about 1200 K.
Black, J.H., Dishoeck, E.F. van
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A search for naphthalene in diffuse interstellar clouds
, 2011 We have obtained high resolution optical spectroscopy of 10 reddened O-type stars with UVES at VLT to search for interstellar bands of the naphthalene cation (C$_{10}$H$_{8}$$^+$) in the intervening clouds. No absorption features were detected near the laboratory strongest band of this cation at 6707 Åexcept for star HD 125241 (O9 I).
Iglesias-Groth, Susana +2 more
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The carbon abundance in diffuse interstellar clouds
The Astrophysical Journal, 1981 When N/sub H2/roughly-equal1-40 x 10/sup 19/ cm/sup -2/ in a given direction, or f equivalent 2N/sub H2//N/sub H/>10/sup -1.4/, the column densities of C I and H/sub 2/ are strongly correlated even though N/sub C/ /sub i/ and N/sub H/ are not. All or most of the observed C I in such directions is harbored by a single, predominantly molecular (H/sub 2/>>
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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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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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The Astrophysical JournalMolecular hydrogen (H _2 ) formation and dissociation are key processes that drive the gas life cycle in galaxies. Using the SImulating the LifeCycle of Molecular Clouds zoom-in simulation suite, we explore the utility of future observations of H _2 ...
Blakesley Burkhart +13 more
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