J/MNRAS/505/963 Vanishing natural coronagraph of eta Car (Damineli+, 2021)
Spectroscopic signatures of the vanishing natural coronagraph of eta Carinae.
Damineli A., Navarete F., Hillier D.J., Moffat A.J., Corcoran M.F.,
Gull T.R., Richardson N.D., Weigelt G., Morris P.W., Stevens I.
<Mon. Not. R. Astron. Soc. 505, 963 (2021)>
=2021MNRAS.505..963D 2021MNRAS.505..963D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Equivalent widths
Keywords: stars: binaries - stars: individual: eta Carinae - stars: winds
ISM: dust, extinction - ISM: molecules
Abstract:
Eta Carinae is a massive interacting binary system shrouded in a
complex circumstellar environment whose evolution is the source of the
long-term brightening observed during the last 80yr. An occulter,
acting as a natural coronagraph, impacts observations from our
perspective, but not from most other directions. Other sight-lines are
visible to us through studies of the Homunculus reflection nebula. The
coronagraph appears to be vanishing, decreasing the extinction towards
the central star, and causing the star's secular brightening. In
contrast, the Homunculus remains at an almost constant brightness. The
coronagraph primarily suppresses the stellar continuum, to a lesser
extent the wind lines, and not the circumstellar emission lines. This
explains why the absolute values of equivalent widths (EWs) of the
emission lines in our direct view are larger than those seen in
reflected by the Homunculus, why the direct view absolute EWs are
decreasing with time, and why lower-excitation spectral wind lines
formed at larger radii (e.g FeII 4585Å) decrease in intensity at a
faster pace than higher excitation lines that form closer to the star
(e.g. Hδ). Our main result is that the star, despite its 10-fold
brightening over two decades, is relatively stable. A vanishing
coronagraph that can explain both the large flux evolution and the
much weaker spectral evolution. This is contrary to suggestions that
the long-term variability is intrinsic to the primary star that is
still recovering from the Great Eruption with a decreasing mass-loss
rate and a polar wind that is evolving at a slower pace than at the
equator.
Description:
These are the full versions of Tables A3, A4 and A5 of the manuscript.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea3.dat 31 285 Equivalent width in direct light of Hα
tablea4.dat 34 280 Equivalent width in direct light of FeII 4585Å
tablea5.dat 34 172 Equivalent width in direct light of Hδ
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See also:
J/ApJS/71/983 : UV spectrum of eta Car (Viotti+ 1989)
J/A+A/304/415 : uvby-Hbeta photometry of Eta Car 1992-94 (van Genderen+, 1995)
J/A+A/343/847 : Geneva Photometry of Eta Car (van Genderen+ 1999)
J/A+A/419/215 : Emission lines of Sr filament near η Car (Hartman+, 2004)
J/AJ/129/2018 : RXTE scaled fluxes of eta Car (Corcoran+, 2005)
J/ApJS/157/138 : UV spectrum of eta Car (Nielsen+, 2005)
J/ApJS/163/173 : UV spectrum of eta Car in 2003.5 (Gull+, 2006)
J/ApJS/168/289 : NUV spectrum of eta Car in 2003.5 (Nielsen+, 2007)
J/A+A/493/1093 : BVRI light curves of η Car (Fernandez-Lajus+, 2009)
J/ApJS/181/473 : Analysis of the spectrum of η Car (Nielsen+, 2009)
J/A+A/540/A133 : η Car emission spectrum (1700-10400Å) (Zethson+, 2012)
J/AJ/150/109 : Spectroscopy of η Car in 2009 (Richardson+, 2015)
J/A+A/594/A106 : eta Car velocity-resolved imaging (Weigelt+, 2016)
Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d HJD Heliocentric Julian Day (HJD-2400000)
11- 15 I5 0.1nm EWHa Equivalent width of Hα
17- 19 I3 0.1nm e_EWHa Error on EWHa measurement
21- 31 A11 --- Site Site
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d HJD Heliocentric Julian Day (HJD-2400000)
11- 15 F5.1 0.1nm EWFeII Equivalent width of FeII 4585Å
17- 20 F4.1 0.1nm e_EWFeII Error on EWFeII measurement
23- 35 A13 --- Site Site
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 d HJD Heliocentric Julian Day (HJD-2400000)
11- 15 F5.1 0.1nm EWHd Equivalent width of Hδ
17- 20 F4.1 0.1nm e_EWHd Error on EWHd measurement
23- 35 A13 --- Site Site
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Acknowledgements:
Felipe Navarete, navarete(at)usp.br
(End) Patricia Vannier [CDS] 17-May-2021