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High-Velocity Absorption Features in FUSE Spectra of Eta CarinaeNumerous broad (200 to 1000 km/sec) features in the FUSE spectrum (905-1187 A) of eta Carinae are identified as absorption by a forest of high-velocity narrow lines formed in the expanding circumstellar envelope. These features were previously thought to be P-Cygni lines arising in the wind of the central star. The features span a heliocentric velocity range of -140 to -580 km/sec and are seen prominently in low-ionization ground-state transitions (e.g. N I 1134-35, Fe II 1145-42, 1133, 1127- 22, P II 1153, C I 1158) in addition to C III] 1176 A. The high-velocity components of the FUSE transitions have depths about 50% below the continuum. The identifications are consistent with the complex velocity structures seen in ground- and excited-state transitions of Mg I, Mg 11, Fe II, V II, etc observed in STIS/E230H spectra. The origin of other broad features of similar width and depth in the FUSE spectrum, but without low-velocity ISM absorption, are unidentified. However, they are suspected of being absorption of singly-ionized iron-peak elements (e.g. Fe II, V II, Cr II) out of excited levels 1,000 to 20,000 cmE-l above the ground state. The high-velocity features seen in Fe II 1145 are also present in Fe II 1608 (STIS/E140M), but are highly saturated in the latter. Since these transitions have nearly identical log (flambda) (1.998 vs. 2.080), the differences in the profiles are attributable to the different aperture sizes used (30 x 30 arcsec for FUSE, 0.2 x 0.2 arcsec for STIS/E140M). The high-velocity gas appears to be very patchy or has a small covering factor near the central star. Eta Carinae has been observed several times by FUSE over the past three years. The FUSE flux levels and spectral features in eta Car are essentially unchanged over the 2000 March to June 2002 period, establishing a baseline far-UV spectrum in advance of the predicted spectroscopic minimum in 2003.
Document ID
20040034182
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Sonneborn, G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Iping, R. C.
(Catholic Univ. of America Washington, DC, United States)
Gull, T. R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Vieira, G.
(Science Systems and Applications, Inc. Greenbelt, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Astrophysics
Meeting Information
Meeting: American Astronomical Society Meeting
Location: Seattle, WA
Country: United States
Start Date: January 5, 2003
End Date: January 9, 2003
Sponsors: American Astronomical Society
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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