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Full-Text Articles in Physics
Nebular Properties And The Ionizing Radiation Field In The Galactic Center, Joseph C. Shields, Gary J. Ferland
Nebular Properties And The Ionizing Radiation Field In The Galactic Center, Joseph C. Shields, Gary J. Ferland
Physics and Astronomy Faculty Publications
Nebulosity in the central parsec of the Milky Way exhibits a low-ionization spectrum that has led previous analyses of this region to conclude that this material is photoionized by a relatively soft continuum. We have reanalyzed the infrared emission-line spectrum of te Galactic center in order to consider whether the data could actually be explained with photoionization by a relatively hard, yet dilute continuum, and additionally to constrain the properties of the reaiating plasma. We conclude that the composite infrared spectrum does not place strong restrictions on the nature of the ionizing continuum and that much of the ionized gas …
On The Theory Of Astronomical Masers In Three Dimensions, Moshe Elitzur
On The Theory Of Astronomical Masers In Three Dimensions, Moshe Elitzur
Physics and Astronomy Faculty Publications
In the standard theory of three-dimensional astronomical masers, the radiation field is described as if the source were comprised of a collection of linear masers. To leading order, the standard theory is shown to provide the correct description of three-dimensional masers and its results remain intact, but only within a frequency core whose half-width is χsΔνD, where ΔνD is the Doppler width and χs is a dimensionless parameter. For any given geometry, χs is ~1θsat, where θsat is the beaming angle of a maser with that geometry that has …