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T.R. Gull (NASA/GSFC/LASP), K. Ishibashi (NAS/NRC at GSFC), K. Davidson (UMN), T. Zethson, S. Johannson, H. Hartman (Univ of Lund), Eta Carinae Cycle 7 and 8 Collaboration
Observations of the ejecta associated with Eta Carinae were done using the Space Telescope Imaging Spectrograph (STIS) with CCD and grating settings yielding resolving power ~5000 during four visits between December 1997 and February 1999. The identical position and position angle was utilized for the March 1998 and February 1999 observations that are continuous from 1640 to 10400A. In eleven months, considerable changes in nebular structure, nebular brightness, emission lines and absorption lines have taken place. Moreover, the nebular structures change rapidly on a scale of 0.1", the angular resolution of the STIS CCD.
We have been systematically identifying both the emission lines and absorption lines present in the nebular spectrum. Multiple fluorescent lines are present and have changed considerably in intensity. Most notable is the change in iron ionization. Effectively the near ultraviolet transparency has increased due to conversion of much iron from Fe II to Fe III.
This activity is funded by NASA through STIS GTO and STScI GO resources and through University of Lund, Sweden.
The author(s) of this abstract have provided an email address for comments about the abstract: gull@sea.gsfc.nasa.gov