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Astrophysical lasers in optical Fe II lines in gas condensations near η Carinae

Johansson, Sveneric LU and Letokhov, Vladilen LU (2005) Atomic Physics 19. 19th International Conference on Atomic Physics ICAP 2004 In Atomic Physics 19 770. p.399-410
Abstract
We report here on the discovery of laser action in the range 0.9-2 μm in several spectral lines of Fe II, which are associated with transitions from "pseudo-metastable" states populated by spontaneous transitions from Lyα pumped Fe II levels. The intense Lyα radiation is formed in the HII region of gas condensations close to the star η Car. The laser transitions form together with spontaneous transitions closed radiative cycles, one of which includes the extremely bright 2507/09 Å lines. This fact, together with an accidental mixing of energy levels, may provide an explanation of the abnormal intensities of these UV non-lasing lines. Using the complicated energy level diagram of Fe II we present those peculiar features, which are essential... (More)
We report here on the discovery of laser action in the range 0.9-2 μm in several spectral lines of Fe II, which are associated with transitions from "pseudo-metastable" states populated by spontaneous transitions from Lyα pumped Fe II levels. The intense Lyα radiation is formed in the HII region of gas condensations close to the star η Car. The laser transitions form together with spontaneous transitions closed radiative cycles, one of which includes the extremely bright 2507/09 Å lines. This fact, together with an accidental mixing of energy levels, may provide an explanation of the abnormal intensities of these UV non-lasing lines. Using the complicated energy level diagram of Fe II we present those peculiar features, which are essential for the inverted population and laser effect: the pumping, the level mixing, and the "bottle neck" for spontaneous decay. The laser action is a new indicator of non-equilibrium and spatially non-homogeneous physical conditions as well as a high brightness temperature of Lyα in ejecta from eruptive stars. Such conditions are very difficult to probe by existing methods (Less)
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author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
spontaneous transitions, intense radiation, laser transitions, radiative cycles, abnormal intensities, UV nonlasing lines, energy level diagram, laser effect, optical pumping, level mixing, spontaneous decay, Fe<sub>+</sub>, 0.9 to 2 micron, stellar radiation, stimulated emission, astrophysical plasma, brightness temperature, eruptive stars, pseudometastable states, laser action, η Carinae, gas condensations, astrophysical lasers, optical Fe II lines
in
Atomic Physics 19
volume
770
pages
399 - 410
publisher
American Institute of Physics
conference name
Atomic Physics 19. 19th International Conference on Atomic Physics ICAP 2004
external identifiers
  • wos:000229959800040
  • scopus:33749486512
ISSN
1551-7616
0094-243X
DOI
10.1063/1.1928874
language
English
LU publication?
yes
id
5f3e20c5-9f9a-4abe-bc49-9bd72dd1b504 (old id 616535)
alternative location
http://adsabs.harvard.edu/abs/2004A&A...428..497J
date added to LUP
2007-11-25 12:46:51
date last changed
2017-06-11 03:28:15
@inproceedings{5f3e20c5-9f9a-4abe-bc49-9bd72dd1b504,
  abstract     = {We report here on the discovery of laser action in the range 0.9-2 μm in several spectral lines of Fe II, which are associated with transitions from "pseudo-metastable" states populated by spontaneous transitions from Lyα pumped Fe II levels. The intense Lyα radiation is formed in the HII region of gas condensations close to the star η Car. The laser transitions form together with spontaneous transitions closed radiative cycles, one of which includes the extremely bright 2507/09 Å lines. This fact, together with an accidental mixing of energy levels, may provide an explanation of the abnormal intensities of these UV non-lasing lines. Using the complicated energy level diagram of Fe II we present those peculiar features, which are essential for the inverted population and laser effect: the pumping, the level mixing, and the "bottle neck" for spontaneous decay. The laser action is a new indicator of non-equilibrium and spatially non-homogeneous physical conditions as well as a high brightness temperature of Lyα in ejecta from eruptive stars. Such conditions are very difficult to probe by existing methods},
  author       = {Johansson, Sveneric and Letokhov, Vladilen},
  booktitle    = {Atomic Physics 19},
  issn         = {1551-7616},
  keyword      = {spontaneous transitions,intense radiation,laser transitions,radiative cycles,abnormal intensities,UV nonlasing lines,energy level diagram,laser effect,optical pumping,level mixing,spontaneous decay,Fe<sub>+</sub>,0.9 to 2 micron,stellar radiation,stimulated emission,astrophysical plasma,brightness temperature,eruptive stars,pseudometastable states,laser action,η Carinae,gas condensations,astrophysical lasers,optical Fe II lines},
  language     = {eng},
  pages        = {399--410},
  publisher    = {American Institute of Physics},
  title        = {Astrophysical lasers in optical Fe II lines in gas condensations near η Carinae},
  url          = {http://dx.doi.org/10.1063/1.1928874},
  volume       = {770},
  year         = {2005},
}