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Metastable hydrogen absorption in ejecta close to eta Carinae

Johansson, Sveneric LU ; Gull, TR; Hartman, Henrik LU and Letokhov, Vladilen LU (2005) In Astronomy & Astrophysics 435(1). p.183-189
Abstract
Spectroscopy with the high spatial resolution of the Hubble Space Telescope (HST) reveals narrow absorption in the hydrogen Balmer lines in spectra of Eta Carinae and the nearby nebular-scattered starlight. While hydrogen Balmer absorption lines are seen in stellar photospheres and winds, we are not aware of such being seen in galactic nebulae. This exceptional case is caused by intense stellar UV radiation acting on high-density neutral clumps of gas in the close vicinity of the central source. The interaction of the UV radiation with hydrogen results in photo-ionization and photo-excitation leading to a non-equilibrium population of the metastable 2s S-2 level. This occurs throughout the equatorial region surrounding eta Carinae in... (More)
Spectroscopy with the high spatial resolution of the Hubble Space Telescope (HST) reveals narrow absorption in the hydrogen Balmer lines in spectra of Eta Carinae and the nearby nebular-scattered starlight. While hydrogen Balmer absorption lines are seen in stellar photospheres and winds, we are not aware of such being seen in galactic nebulae. This exceptional case is caused by intense stellar UV radiation acting on high-density neutral clumps of gas in the close vicinity of the central source. The interaction of the UV radiation with hydrogen results in photo-ionization and photo-excitation leading to a non-equilibrium population of the metastable 2s S-2 level. This occurs throughout the equatorial region surrounding eta Carinae in sufficient quantity to produce strong narrow absorption on top of the broad P Cygni emission profile. This absorption can be considered to be a probe of the very non-uniform ejecta in the disk region surrounding eta Carinae. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars : individual : eta Carinae, radiation mechanisms : non-thermal, HII regions, line : profiles, atomic processes, line : formation
in
Astronomy & Astrophysics
volume
435
issue
1
pages
183 - 189
publisher
EDP Sciences
external identifiers
  • wos:000228690500023
  • scopus:18744413935
ISSN
0004-6361
DOI
10.1051/0004-6361:20041193
language
English
LU publication?
yes
id
ed12052e-985d-47a7-91ce-68cc1adfdf32 (old id 244568)
date added to LUP
2007-08-17 17:01:18
date last changed
2017-07-09 04:28:52
@article{ed12052e-985d-47a7-91ce-68cc1adfdf32,
  abstract     = {Spectroscopy with the high spatial resolution of the Hubble Space Telescope (HST) reveals narrow absorption in the hydrogen Balmer lines in spectra of Eta Carinae and the nearby nebular-scattered starlight. While hydrogen Balmer absorption lines are seen in stellar photospheres and winds, we are not aware of such being seen in galactic nebulae. This exceptional case is caused by intense stellar UV radiation acting on high-density neutral clumps of gas in the close vicinity of the central source. The interaction of the UV radiation with hydrogen results in photo-ionization and photo-excitation leading to a non-equilibrium population of the metastable 2s S-2 level. This occurs throughout the equatorial region surrounding eta Carinae in sufficient quantity to produce strong narrow absorption on top of the broad P Cygni emission profile. This absorption can be considered to be a probe of the very non-uniform ejecta in the disk region surrounding eta Carinae.},
  author       = {Johansson, Sveneric and Gull, TR and Hartman, Henrik and Letokhov, Vladilen},
  issn         = {0004-6361},
  keyword      = {stars : individual : eta Carinae,radiation mechanisms : non-thermal,HII regions,line : profiles,atomic processes,line : formation},
  language     = {eng},
  number       = {1},
  pages        = {183--189},
  publisher    = {EDP Sciences},
  series       = {Astronomy & Astrophysics},
  title        = {Metastable hydrogen absorption in ejecta close to eta Carinae},
  url          = {http://dx.doi.org/10.1051/0004-6361:20041193},
  volume       = {435},
  year         = {2005},
}