Can quasar clouds form in thermal instabilities

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168548· OSTI ID:6806713

Mathews, W G; Doane, J S ^[1]

---

1. Lick Observatory, Santa Cruz, CA (USA)

Consideration is given to the hypothesis that the broad line-emitting clouds in quasars and Seyfert galaxies form from thermally unstable condensations in a hot cloud-confining medium. A simple model for the radiative cooling rate is described and the magnitude of the initial perturbation needed to form broad-line clouds in quasars is examined. The hydrodynamical evolution of thermally unstable regions in quiescent and expanding hot quasar atmospheres is studied. The results suggest that emission-line clouds are unlikely to arise from thermally unstable condensations in a hotter medium, but are likely to first appear in the broad-line region with densities comparable to or greater than those of typical line-emitting clouds. 18 refs.

• OSTI ID: 6806713
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 352; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COOLING
COSMIC GASES
COSMIC RADIO SOURCES
EMISSION SPECTRA
FLUID MECHANICS
FLUIDS
GALACTIC EVOLUTION
GALAXIES
GASES
HYDRODYNAMICS
INSTABILITY
INTERSTELLAR SPACE
LINE WIDTHS
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
ORIGIN
QUASARS
SEYFERT GALAXIES
SPACE
SPECTRA