Advanced

A model for the origin of the anomalous and very bright UV lines of Fe II in gaseous condensations of the star eta Carinae

Johansson, Sveneric LU and Letokhov, Vladilen LU (2001) In Astronomy & Astrophysics 378. p.266-278
Abstract
We present a qualitative physical model of the origin of two very brightUV lines of Fe II at 2507-2509 Å, present in high-resolutionspectra of gaseous condensations (blobs) close to the central star ofeta Carinae. The spectra have been obtained with the Hubble SpaceTelescope (HST). The model is based on a type of Bowen mechanism withselective photoexcitation of Fe II by a broad HLyalpha profile,generated in the HII region and diffusely transferred to the opticallythick HI region. The frequency distribution by large Doppler diffusioninto the HI region provides a substantial broadening of HLyalpha , whichmakes it possible to selectively photo-excite short-lived (~1 ns) statesat 11.2 eV in Fe II. Within the frame of the present model the... (More)
We present a qualitative physical model of the origin of two very brightUV lines of Fe II at 2507-2509 Å, present in high-resolutionspectra of gaseous condensations (blobs) close to the central star ofeta Carinae. The spectra have been obtained with the Hubble SpaceTelescope (HST). The model is based on a type of Bowen mechanism withselective photoexcitation of Fe II by a broad HLyalpha profile,generated in the HII region and diffusely transferred to the opticallythick HI region. The frequency distribution by large Doppler diffusioninto the HI region provides a substantial broadening of HLyalpha , whichmakes it possible to selectively photo-excite short-lived (~1 ns) statesat 11.2 eV in Fe II. Within the frame of the present model the intenseHLyalpha radiation induces a depletion of the lower, long-lived (~1 ms)level of the strong UV lines by photoionization. The subsequentrecombination of Fe III explains the appearance of the ``forest'' ofnarrow Fe II lines. The possibility of a cyclic process is alsodiscussed, where HLyalpha induces depletion to bound states, which havefast decays in the far-UV to the lower state of the Bowen pumpingchannel. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
RADIATION MECHANSIMS: NON-THERMAL, ATOMIC PROCESSES, LINE: FORMATION, STARS: INDIVIDUAL: ETA CARINAE
in
Astronomy & Astrophysics
volume
378
pages
266 - 278
publisher
EDP Sciences
external identifiers
  • scopus:0035471524
ISSN
0004-6361
DOI
10.1051/0004-6361:20011062
language
English
LU publication?
yes
id
4b42f2b4-e541-4177-9352-3e77b52c9b3b (old id 130136)
date added to LUP
2007-07-13 12:03:12
date last changed
2018-07-01 04:21:04
@article{4b42f2b4-e541-4177-9352-3e77b52c9b3b,
  abstract     = {We present a qualitative physical model of the origin of two very brightUV lines of Fe II at 2507-2509 Å, present in high-resolutionspectra of gaseous condensations (blobs) close to the central star ofeta Carinae. The spectra have been obtained with the Hubble SpaceTelescope (HST). The model is based on a type of Bowen mechanism withselective photoexcitation of Fe II by a broad HLyalpha profile,generated in the HII region and diffusely transferred to the opticallythick HI region. The frequency distribution by large Doppler diffusioninto the HI region provides a substantial broadening of HLyalpha , whichmakes it possible to selectively photo-excite short-lived (~1 ns) statesat 11.2 eV in Fe II. Within the frame of the present model the intenseHLyalpha radiation induces a depletion of the lower, long-lived (~1 ms)level of the strong UV lines by photoionization. The subsequentrecombination of Fe III explains the appearance of the ``forest'' ofnarrow Fe II lines. The possibility of a cyclic process is alsodiscussed, where HLyalpha induces depletion to bound states, which havefast decays in the far-UV to the lower state of the Bowen pumpingchannel.},
  author       = {Johansson, Sveneric and Letokhov, Vladilen},
  issn         = {0004-6361},
  keyword      = {RADIATION MECHANSIMS: NON-THERMAL,ATOMIC PROCESSES,LINE: FORMATION,STARS: INDIVIDUAL: ETA CARINAE},
  language     = {eng},
  pages        = {266--278},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {A model for the origin of the anomalous and very bright UV lines of Fe II in gaseous condensations of the star eta Carinae},
  url          = {http://dx.doi.org/10.1051/0004-6361:20011062},
  volume       = {378},
  year         = {2001},
}