Densities of interstellar hydrogen clouds
- 1 August 1968
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 46 (15) , 1661-1667
- https://doi.org/10.1139/p68-496
Abstract
With simple gas dynamical theory one can calculate three properties of plane and steady supersonic discontinuity fronts: the compression ratio ρ2/ρ1, the density of the undisturbed medium ahead, and the power input W per unit area of front. These calculations do not require knowledge of the absorption mechanism or the spectral distribution of the absorbed (or emitted) radiation, but are based on measurements of particle velocity, density, and temperature behind the front. The calculations were applied to radio observations of galactic H II regions by Mezger and Henderson (1967) and Mezger and Höglund (1967). The derived average density for 11 hydrogen clouds surrounding the observed H II regions corresponds to n(H I) = 50 cm−3, assuming complete dissociation. The objects Orion A and IC 434 stand out with n(H I) = 450 and 405 cm−3, respectively (see Table I). The average power input is W = 5 × 10−3 erg/cm2 s.Keywords
This publication has 0 references indexed in Scilit: