AAS 203rd Meeting, January 2004
Session 58 Eta Carinae
Poster, Tuesday, January 6, 2004, 9:20am-6:30pm, Hanover Hall

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[58.10] Eta Carinae and the 2003.5 Minimum: Ultraviolet Changes of the Central Source and the Very Nearby Ejecta

T.R. Gull (NASA/GSFC), K. E. Nielsen (CUA & NASA/GSFC), G. L. Vieira (SSAI & NASA/GSFC), D.J. Hillier (Univ of Pittsburgh), N. Walborn (STScI), K. Davidson (Univ of Minnesota), Eta Car HST Treasury Team

We utilized the high spatial and high spectral resolution of the HST/STIS MAMA echelle modes in the ultraviolet (0.025" spatial resolution and 30,000 to 120,000 spectral resolving power) to view changes in and around Eta Carinae before and after the X-Ray drop which occurred on June 29, 2003 (M. Corcoran, IAUC 8160). Major changes in the spectra of the Central Source and nearby nebulosities occurred between June 22 and July 5. Visibility of the Central Source dropped, especially between 1175 and 1350A, but not uniformly throughout the uv. This fading is likely due to multiple line absorptions both in the source and in the intervening ejecta.

Nebular emission of Si III] and Fe III, located 0.09" to the west, disappeared. By July 29, a bright feature extending up to 0.07" east of the Central Source became prominent in broad emission lines near 2500A, but was not noticeable longward of 2900A. ACS/HRC imagery and STIS CCD spectra taken concurrently are being examined for larger scale changes.

Numerous narrow velocity components between -146 and -585 km/s were identified in spectra before the minimum. New components appeared primarily in Fe II absorption lines with velocities between -170 and -380 km/s. While the lines of the -513 km/s component did not change, most lines of the -146 km/s component changed considerably. Lines originating from high energy levels diminished or disappeared, while lines originating from lower energy levels strengthened. Strong absorption lines of Ti II, not present before the X-Ray drop, appeared within seven days, but disappeared by July 29.

Further analysis of these unprecedented data will provide significant new information about the structure of Eta Carinae and its periodic variations. This work was supported by funding from STIS GTO, and STScI proposals 9420 and 9973.

The author(s) of this abstract have provided an email address for comments about the abstract: Theodore.R.Gull@NASA.GOV

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