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Journal ArticleDOI

Hot gas in and between galaxies

01 Nov 1975-Astrophysics and Space Science (Kluwer Academic Publishers)-Vol. 38, Iss: 1, pp 167-190
TL;DR: In this article, the fate of interstellar gas heated by energetic radiation and far from the galactic plane is considered, and it is shown that for plausible heating rates a very hot corona forms, separated from the cooler gas in the disk by a conductive boundary layer.
Abstract: The fate of interstellar gas heated by energetic radiation and far from the galactic plane is considered. It is shown that for plausible heating rates a very hot corona forms, separated from the cooler gas in the disk by a conductive boundary layer. For heating rates exceeding a critical value a galactic wind is set up, as first shown by Mathews and Baker for elliptical galaxies. Such winds may fill the intracluster space in clusters of galaxies; further heating may drive a cluster wind, as shown by Yahil and Ostriker. It is believed that the flow problem of intracluster gas in the presence of intercluster gas is not yet adequately solved. A variety of observations at X-ray and ultraviolet wavelengths are needed to resolve these questions.
Citations
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01 Dec 1968
TL;DR: In this article, the authors discuss the attractive and disruptive forces in conversion of interstellar gas into stars, discussing self gravitation, galactic magnetic field and cosmic ray pressure, as well as the effects of star formation.
Abstract: Attractive and disruptive forces in conversion of interstellar gas into stars, discussing self gravitation, galactic magnetic field and cosmic ray pressure

511 citations

Journal ArticleDOI
TL;DR: In this article, a simple semi-analytic model was proposed to trace the thermalisation history of the starburst galaxy and determine the heating efficiency of the supernova explosion (SNE).
Abstract: The interstellar medium heated by supernova explosions (SN) may acquire an expansion velocity larger than the escape velocity and leave the galaxy through a supersonic wind. Galactic winds are effectively observed in many local starburst galaxies. SN ejecta are transported out of the galaxies by such winds which thus affect the chemical evolution of the galaxies. The effectiveness of the processes mentioned above depends on the heating efficiency (HE) of the SNe, i.e. on the fraction of SN energy which is not radiated away. The value of HE, in particular in starburst (SB) galaxies, is a matter of debate. We have constructed a simple semi-analytic model, considering the essential ingredients of a SB environment which is able to qualitatively trace the thermalisation history of the ISM in a SB region and determine the HE evolution. Our study has been also accompanied by fully 3-D radiative cooling, hydrodynamical simulations of SNR-SNR and SNR-clouds interactions. We find that, as long as the typical time scale of mass-loss of the clouds to the ambient medium, which is often dominated by photoevaporation, remains shorter than the time scale at which the SNRs interact to form a superbubble, the SN heating efficiency remains very small, as radiative cooling of the gas dominates. If there is a continuous production of clouds by the gas swept by the SNR shells, this occurs during the first ≤ 16 Myr of the SB activity (of∼30 Myr), after which the efficiency rapidly increases to one, leading to a possible galactic wind formation. Under an extreme condition in which no clouds are allowed to form, other than those that were already initially present in the SB environment, then in this case HE increases to one in only few Myr. We conclude that the HE value has a time-dependent trend that is sensitive to the initial conditions of the system and cannot be simply assumed to be ∼1, as it is commonly done in most SB galactic wind models.

74 citations


Cites background from "Hot gas in and between galaxies"

  • ...Following Field (1975), it is easy to show that this solution is stable....

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Journal ArticleDOI
TL;DR: In this article, a discussion of laboratory spectra similar in temperatures and ion abundances to solar flare spectra is given, and some of the results are used to identify lines in the high temperature solar flare spectrum in the 100 A region and in the 1000 A region.
Abstract: A discussion of laboratory spectra similar in temperatures and ion abundances to solar flare spectra is given. The laboratory spectra were obtained from high temperature plasmas produced by high power lasers and low inductance vacuum sparks. The current state of knowledge regarding line identifications in laboratory spectra is reviewed, and some of the results are used to identify lines in the high temperature solar flare spectrum in the 100 A region and in the 1000 A region. In addition, the physical dimensions and temperatures of the hot regions in the plasmas produced by the low inductance spark were recently measured, and a short summary of the results is given.

10 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed a cyclic model, in which an interstellar gas of a temperature around 104 K is heated to roughly 106 K by type II supernovae resulting from the enhanced star formation triggered by the density wave, and cools down again to 104 K after the supernova activity subsides to be ready for shock compression in the next sweep of density wave pattern.
Abstract: Starting from the argument that the density wave theory of spiral structure is incompatible with the existence of a stationary very hot extended component of the interstellar gas, we develop a cyclic model, in which an interstellar gas of a temperature around 104 K is heated to roughly 106 K by type II supernovae resulting from the enhanced star formation triggered by the density wave, and cools down again to 104 K after the supernova activity subsides to be ready for shock compression in the next sweep of the density wave pattern. The time scales for heating by supernovae and subsequent cooling turn out to be consistent with current density wave theory. The scenario proposed is corroborated by recent results on cosmic ray composition and γ-ray observations.

2 citations

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