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K. E. Nielsen (CUA & NASA/GSFC), T. R. Gull (NASA/GSFC), G. Vieira (SSAI & NASA/GSFC), Eta Car HST Treasury Team
The angular and spectral resolving power of HST/STIS facilitates detailed investigation of the nebular structure immediately surrounding \eta\,Car. During the spectroscopic minimum of 2003.5, we used the MAMA echelle modes with the 0.3"x0.2" aperture which included a portion of the nebula on both sides of the central source. \eta\,Car is slightly extended, it measured 0.03" FWHM permitting recording nebular spectra of about 0.1" extent on each side. From one side of the star to the other, the nebulae show clear differences. Toward the Weigelt blobs, the spectrum includes scattered starlight and many nebular emission lines (-46 km/s) of iron-peak elements with the absence of strong Lyman alpha dependent emission lines. Superimposed on this spectrum is absorption from foreground ejecta with a velocity dispersion between -140 and -50 km/s. East of the central object, the spectrum is primarily scattered starlight with strong Fe II emission in the form of broad P-Cygni stellar wind profiles. The difference in spectral characteristics from Northeast to Southwest of the star can be explained by the wind-wind interaction of a binary system containing two massive stars (Pittard et al 2004) and the associated trapping of hydrogen Lyman radiation. In this poster, we will present a explanation of the nebular structure and how it relates back to the binary system.
These observations were obtained through the STScI; funding was through STIS GTO and HST GO programs.
The author(s) of this abstract have provided an email address for comments about the abstract: nielsen@stis.gsfc.nasa.gov
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.