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Possibility of Measuring the Width of Narrow Fe II Astrophysical Laser Lines in the Vicinity of Eta Carinae by means of Brown-Twiss-Townes Heterodyne Correlation Interferometry
S. Johansson, V. S. Letokhov
We consider the possibility of measuring the true width of the narrow Fe II optical lines observed in spectra of the Weigelt blobs in the vicinity of Eta Carinae. The lines origina…
Astrophysical Lasers Operating in optical Fe II Lines Lines in Stellar Ejecta of Eta Carinae
S. Johansson, V. S. Letokhov
After the discovery of space masers based on OH radicals (Weaver et al, 1965) and H2O (Cheung et al, 1969) such microwave lasers have been found to work in more than 100 molecular…
Fe II Diagnostic Tools for Quasars
E. Verner, F. Bruhweiler, D. Verner +3
The enrichment of Fe, relative to alpha-elements such as O and Mg, represents a potential means to determine the age of quasars and probe the galaxy formation epoch. To explore how…
Identification of Emission Lines in the Low-Ionization Strontium Filament Near Eta Carinae
H. Hartman, T. Gull, S. Johansson +1
We have obtained deep spectra from 1640 to 10100A with the Space Telescope Imaging Spectrograph (STIS) of the Strontium Filament, a largely neutral emission nebulosity lying close…
Revisited abundance diagnostics in quasars: Fe II/Mg II ratios
E. Verner, F. Bruhweiler, D. Verner +2
Both the Fe II UV emission in the 2000- 3000 A region [Fe II (UV)] and resonance emission line complex of Mg II at 2800 A are prominent features in quasar spectra. The observed Fe…
A Radiative Cycle with Stimulated Emission from Atoms (Ions) in an astrophysical Plasma
S. Johansson, V. S. Letokhov
We propose that a radiative cycle operates in atoms (ions) located in a rarefied gas in the vicinity of a hot star. Besides spontaneous transitions the cycle includes a stimulated…