Interstellar Neutral Potassium and Neutral Calcium

Dunham, Theodore

doi:10.1086/124759

Cited by 149 publications

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“…While most of the molecular gas is concentrated in molecular clouds and their star-forming cores, the discovery of molecules in the diffuse phase (Dunham 1937;Swings & Rosenfeld 1937) came as a surprise, given the strong dissociating UV radiation in the Galaxy. An account of the historical development is given in Cox (2005).…”

Section: Introductionmentioning

confidence: 99%

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Wiesemeyer

Güsten

Heyminck

et al. 2015

A&A

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Context. The chemistry of the diffuse interstellar medium rests upon three pillars: exothermic ion-neutral reactions ("cold chemistry"), endothermic neutral-neutral reactions with significant activation barriers ("warm chemistry"), and reactions on the surfaces of dust grains. While warm chemistry becomes important in the shocks associated with turbulent dissipation regions, the main path for the formation of interstellar OH and H 2 O is that of cold chemistry. Aims. The aim of this study is to observationally confirm the association of atomic oxygen with both atomic and molecular gas phases, and to understand the measured abundances of OH and OH + as a function of the available reservoir of H 2 . Methods. We obtained absorption spectra of the ground states of OH, OH + and O i with high-velocity resolution, with GREAT onboard SOFIA, and with the THz receiver at the APEX. We analyzed them along with ancillary spectra of HF and CH from HIFI. To deconvolve them from the hyperfine structure and to separate the blend that is due to various velocity components on the sightline, we fit model spectra consisting of an appropriate number of Gaussian profiles using a method combining simulated annealing with downhill simplex minimization. Together with HF and/or CH as a surrogate for H 2 , and H i λ21 cm data, the molecular hydrogen Results. The column density of O i is correlated at a high significance with the amount of available molecular and atomic hydrogen, with an atomic oxygen abundance of 3 × 10 −4 relative to H nuclei. While the velocities of the absorption features of OH and OH + are loosely correlated and reflect the spiral arm crossings on the sightline, upon closer inspection they display an anticorrespondence. The arm-to-interarm density contrast is found to be higher in OH than in OH + . While both species can coexist, with a higher abundance in OH than in OH + , the latter is found less frequently in absence of OH than the other way around, which is a direct consequence of the rapid destruction of OH + by dissociative recombination when not enough H 2 is available. This conjecture has been substantiated by a comparison between the OH/OH + ratio with f, showing a clear correlation. The hydrogen abstraction reaction chain+ is confirmed as the pathway for the production of OH and H 2 O. Our estimate of the branching ratio of the dissociative recombination of H 3 O + to OH and H 2 O is confined within the interval of 84 to 91%, which matches laboratory measurements (74 to 83%). -A correlation between the linewidths and column densities of OH + features is found to be significant with a false-alarm probability below 5%. Such a correlation is predicted by models of interstellar MHD turbulence. For OH the same correlation is found to be insignificant because there are more narrow absorption features. Conclusions. While it is difficult to assess the contributions of warm neutral-neutral chemistry to the observed abundances, it seems fair to conclude that the predictions of cold ion-neutral chemistry match t...

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Section: Introductionmentioning

confidence: 99%

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Wiesemeyer

Güsten

Heyminck

et al. 2015

A&A

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“…Toward the latter, optical absorption measurements have shown for a very long time large abundances of another ionized molecule, methylidynium, CH + , the first interstellar molecule, detected by Dunham (1937) and identified by Douglas & Herzberg (1941). CH + 's abundance is orders of magnitude higher than predicted by otherwise successful models (see, e.g., van Dishoeck & Black 1986).…”

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Submillimeter absorption from SH⁺, a new widespread interstellar radical,¹³CH⁺and HCl

Menten

Wyrowski

Беллоче

et al. 2010

A&A

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104

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We have used the Atacama Pathfinder Experiment 12 m telescope (APEX) to carry out an absorption study of submillimeter wavelength rotational ground-state lines of H 35 Cl, H 37 Cl, 13 CH + , and, for the first time, of the SH + radical (sulfoniumylidene or sulfanylium). We detected the quartet of ground-state hyperfine structure lines of SH + near 683 GHz with the CHAMP+ array receiver against the strong continuum source Sagittarius B2, which is located close to the center of our Galaxy. In addition to absorption from various kinematic components of Galactic center gas, we also see absorption at the radial velocities belonging to intervening spiral arms. This demonstrates that SH + is a ubiquitous component of the diffuse interstellar medium. We do not find clear evidence for other SH + lines we searched for, which is partially due to blending with lines from other molecules. In addition to SH + , we observed absorption from H 35 Cl, H 37 Cl, and 13 CH + . The observed submillimeter absorption is compared in detail with absorption in 3 mm transitions of H 13 CO + and c-C 3 H 2 and the CO J = 1−0 and 3−2 transitions.

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“…All the rest reduce to re-formulations of Lemaître's concept of the (in his own words) "Cosmic Egg exploding at the moment of the creation" that was proven to be absolutely erroneous and fully misleading by nuclear physicists already before the end of the 1930s of the last century [55][56][57][58][59] and onwards to the 1940s [60][61][62][63][64][65][66], where the activity in this direction was extraordinary. For many reasons, it was by then already appreciated that it was absolutely impossible that the whole matter and energy of the present universe could have been initially present, already, and confined to a nutshell.…”

Section: Some Common Popular Sources On the Big Bangmentioning

confidence: 99%

“All That Matter ... in One Big Bang ...,” & Other Cosmological Singularities

Elizalde¹

2018

Preprint

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Abstract:The first part of this paper contains a brief description of the beginnings of modern cosmology, which, the author will argue, was most likely born in the year 1912. Some of the pieces of evidence presented here have emerged from recent research in the history of science and are not usually shared with the general audiences in popular science books. In particular, the issue of the correct formulation of the original Big Bang concept, according to the precise words of Fred Hoyle, is discussed. Too often, this point is very deficiently explained (when not just misleadingly) in most of the available generalist literature. Other frequent uses of the same words, Big Bang, as to name the initial singularity of the cosmos, and also whole cosmological models, are then addressed, as evolutions of its original meaning. Quantum and inflationary additions to the celebrated singularity theorems by Penrose, Geroch, Hawking and others led to subsequent results by Borde, Guth and Vilenkin. Additionally, corresponding corrections to the Einstein field equations have originated, in particular, R 2 , f (R), and scalar-tensor gravities, giving rise to a plethora of new singularities. For completeness, an updated table with a classification of the same is given.

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Interstellar Neutral Potassium and Neutral Calcium

Cited by 149 publications

References 0 publications

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Submillimeter absorption from SH⁺, a new widespread interstellar radical,¹³CH⁺and HCl

“All That Matter ... in One Big Bang ...,” & Other Cosmological Singularities

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Interstellar Neutral Potassium and Neutral Calcium

Cited by 149 publications

References 0 publications

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Far-infrared study of tracers of oxygen chemistry in diffuse clouds

Submillimeter absorption from SH+, a new widespread interstellar radical,13CH+and HCl

&ldquo;All That Matter ... in One Big Bang ...,&rdquo; &amp; Other Cosmological Singularities

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Submillimeter absorption from SH⁺, a new widespread interstellar radical,¹³CH⁺and HCl

“All That Matter ... in One Big Bang ...,” & Other Cosmological Singularities