Showing papers by "Jeremiah P. Ostriker published in 1981"
TL;DR: In this paper, a set of mass distribution models for the Galaxy is presented, wherein the relative predominance of the ''dark'' corona is parametrized by the escape velocity of the Sun.
Abstract: A set of mass distribution models for the Galaxy is presented, wherein the relative predominance of the ''dark'' corona is parametrized by the escape velocity of the Sun. Currently existing Galactic structure information is used to select a small range of models probably in good agreement with the true gross large-scale structure of the Galaxy. The method used is ''objective''in that no assumed mass-to-light ratios are used; rather, the results are derived from a process of minimizing chi/sup 2/ given known kinematical measurements with their estimated associated errors.
273 citations
TL;DR: In this article, conditions for the existence of a hydrodynamic instability by which galaxy formation leads to more galaxy formation due to the propagation of the energy released at the death of massive stars are examined, and it is shown that such an explosive amplification is possible at redshifts less than about 5 and stellar system masses between 10 to the 8th and 10 to 12th solar masses.
Abstract: The evolution of galaxies in an intergalactic medium dominated by explosions of star systems is considered analogously to star formation by nonlinearly interacting processes in the interstellar medium. Conditions for the existence of a hydrodynamic instability by which galaxy formation leads to more galaxy formation due to the propagation of the energy released at the death of massive stars are examined, and it is shown that such an explosive amplification is possible at redshifts less than about 5 and stellar system masses between 10 to the 8th and 10 to the 12th solar masses. Explosions before a redshift of about 5 are found to lead primarily to the formation of massive stars rather than galaxies, while those at a redshift close to 5 will result in objects of normal galactic scale. The model also predicts a dusty interstellar medium preventing the detection of objects of redshift greater than 3, numbers and luminosities of protogalaxies comparable to present observations, unvirialized groups of galaxies lying on two-dimensional surfaces, and a significant number of black holes in the mass range 1000-10,000 solar masses.
264 citations
TL;DR: In this paper, the first numerical simulations of supernova remnant evolution in an inhomogeneous gas are presented, where mass momentum and energy transfer between cloud and intercloud are included and the position and morphology of individual clouds tracked.
Abstract: The first numerical simulations of supernova remnant evolution in an inhomogeneous gas are presented. Evolution in the lowest density substrate (the intercloud) is assumed to be spherically symmetric with a large intercloud filling factor and many dense regions (clouds) within the remnant; however, mass momentum and energy transfer between cloud and intercloud are included and the position and morphology of individual clouds tracked. Evolution is considered in several different models of the interstellar medium, both those in which the intercloud gas is diffuse (0.001 to 0.01/cu cm) and those in which it is relatively dense (n approximately 0.3/cu cm) under a variety of assumptions about the efficiency of thermal evaporation from the clouds into the intercloud medium.
155 citations
01 Jan 1981
TL;DR: In this article, a scenario is put forward to explain these facts which depends primarily on one assumption: the explosive energy released on the death of massive stars in forming stellar systems will propagate into the intergalactic medium.
Abstract: Galaxies appear to have formed at a certain epoch, to display certain characteristic mass and size scales, and to have originated from quite small perturbations. A scenario is put forward to explain these facts which depends primarily on one assumption: the explosive energy released on the death of massive stars in forming stellar systems will propagate into the intergalactic medium. It then follows under certain circumstances, that a dense cooled shell will form with mass many times greater than the original “seed” system, whereupon gravitational instability and fragmentation of the shell can lead to the formation of new stellar systems. For z ≲ 5 and for masses 108 ⩽ M/M⊙ ⩽ 1012 a very large amplification of original perturbations is possible with galaxies naturally forming in small groups having velocity dispersions of order 100 km/s (the velocity at cooling of radiative shells). Explosions before z ≈ 5, which cool primarily due to the inverse Compton interaction with background radiation, will lead to production of very massive stars rather than galaxies.