Issue |
A&A
Volume 419, Number 1, May III 2004
|
|
---|---|---|
Page(s) | 215 - 224 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20035647 | |
Published online | 23 April 2004 |
Identification of emission lines in the low-ionization strontium filament near Eta Carinae *,**
1
Atomic Astrophysics, Lund Observatory, Lund University, Box 43, 221 00 Lund, Sweden
2
Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771, USA
3
CASA, 389 UCB, University of Colorado, Boulder, CO 80309, USA
Corresponding author: H. Hartman, henrik.hartman@astro.lu.se
Received:
7
November
2003
Accepted:
10
February
2004
We have obtained deep spectra from 1640 to 10 100 Å
with the Space Telescope Imaging Spectrograph (STIS) of the
strontium filament, a largely neutral emission nebulosity lying
close to the very luminous star Eta Carinae and showing an uncommon
spectrum. Over 600 emission
lines, both permitted and forbidden, have been identified. The
majority originates from neutral or singly-ionized iron group
elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Sr is the only neutron
capture element detected. The presence of Sr II, numerous strong
and
lines and the dominance of
over
are
notable discoveries. While emission lines of hydrogen, helium, and
nitrogen are associable with other spatial structures at other
velocities within the Homunculus, no emission lines from these
elements correspond to the spatial structure or velocity of the
filament. Moreover, no identified
filament
emission line requires an ionization or excitation energy above
approximately 8 eV. Ionized gas extends spatially along the
aperture, oriented along the polar axis of the Homunculus, and in
velocity around the strontium filament. We suggest that the
strontium filament is shielded from ultraviolet radiation at
energies above 8 eV, but is intensely irradiated by the central
star at wavelengths longward of 1500 Å.
Key words: line: identification / stars: circumstellar matter / stars: kinematics / stars: individual: Eta Carinae
© ESO, 2004
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