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Lego Figure holding a lego telescope. Photo

Henrik Hartman

Researcher (Leave of Absence)

Lego Figure holding a lego telescope. Photo

Metastable hydrogen absorption in ejecta close to eta Carinae

Author

  • Sveneric Johansson
  • TR Gull
  • Henrik Hartman
  • Vladilen Letokhov

Summary, in English

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.

Department/s

  • Lund Observatory - Undergoing reorganization

Publishing year

2005

Language

English

Pages

183-189

Publication/Series

Astronomy & Astrophysics

Volume

435

Issue

1

Document type

Journal article

Publisher

EDP Sciences

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • stars : individual : eta Carinae
  • radiation mechanisms : non-thermal
  • HII regions
  • line : profiles
  • atomic processes
  • line : formation

Status

Published

ISBN/ISSN/Other

  • ISSN: 0004-6361