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Articles 1 - 3 of 3
Full-Text Articles in Physics
Stimulated Emission And The Flat Balmer Decrements Of Cataclysmic Variable Stars, Moshe Elitzur, Gary J. Ferland, W. G. Mathews, G. A. Shields
Stimulated Emission And The Flat Balmer Decrements Of Cataclysmic Variable Stars, Moshe Elitzur, Gary J. Ferland, W. G. Mathews, G. A. Shields
Physics and Astronomy Faculty Publications
Balmer emission lines from cataclysmic variables often have nearly equal intensities rather than the rapid decrement predicted by simple nebular theory. Traditionally, this has been interpreted in terms of local thermodynamic equilibrium emission from a dense gas with small volume located just above the accretion disk. In this Letter we show that the intense radiation field within a close binary system can affect excited-state populations and optical emission in ways which allow a relatively low density gas to closely mimic the high-density situation. In at least one case, the old nova V603 Aql, the emitting gas has a low density …
Reflections In A Polished Tube, Laurence A. Marschall, Emma Beth Marschall
Reflections In A Polished Tube, Laurence A. Marschall, Emma Beth Marschall
Physics and Astronomy Faculty Publications
When one of us (E.B.M.) dislodged a metal tube from an electric door chime recently, she inadvertently introduced her father to an attractive and instructive optical phenomenon. Looking down the highly polished inner surface of the cylinder we could see a spot surrounded by a series of bright concentric rings. The pattern looked much like the display of fringes produced by a Fabry-Perot or Michelson interferometer, except that the rings were more evenly spaced instead of crowding together strongly near the edge of the field of view. [excerpt]
Are There Any Shock-Heated Galaxies?, Gary J. Ferland, Hagai Netzer
Are There Any Shock-Heated Galaxies?, Gary J. Ferland, Hagai Netzer
Physics and Astronomy Faculty Publications
We study the spectroscopic characteristics of low ionization nuclear emission-line regions (Liners) in galaxies, and compare them with other active galactic nuclei. We show the results of new, extensive photoionization model calculations and use them to investigate line ratio diagrams, such as [O III] λ5007/Hβ versus [O II] λ3727/[O III] λ5007, and [O I] λ6300/[O III] λ5007 versus [O III] λ3727/[O III] λ5007. On the diagrams broad line objects, Seyfert 2 galaxies, and Liners form a continuous smooth sequence of decreasing ionization parameter. This suggests a common origin for line excitation in …