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Spectroscopic signatures of the vanishing natural coronagraph of Eta Carinae

Damineli, A. and Navarete, F. and Hillier, D. J. and Moffat, A. F. J. and Corcoran, M. F. and Gull, T. R. and Richardson, N. D. and Weigelt, G. and Morris, P. W. and Stevens, I. (2021) Spectroscopic signatures of the vanishing natural coronagraph of Eta Carinae. Monthly Notices of the Royal Astronomical Society, 505 (1). pp. 963-978. ISSN 0035-8711. doi:10.1093/mnras/stab1398.

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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 80 yr. 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 Fe II 4585 Å) decrease in intensity at a faster pace than higher excitation lines that form closer to the star (e.g. H δ). 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemData
Damineli, A.0000-0002-7978-2994
Navarete, F.0000-0002-0284-0578
Hillier, D. J.0000-0001-5094-8017
Moffat, A. F. J.0000-0002-4333-9755
Corcoran, M. F.0000-0002-7762-3172
Gull, T. R.0000-0002-6851-5380
Richardson, N. D.0000-0002-2806-9339
Weigelt, G.0000-0001-9754-2233
Morris, P. W.0000-0002-5186-4381
Stevens, I.0000-0001-7673-4340
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 May 10. Received 2021 May 10; in original form 2021 February 28. Published: 17 May 2021. AD thanks to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for support award numbers 2011/51680-6 and 2019/02029-2. FN acknowledges FAPESP (2017/18191-8). AFJM is grateful for financial aid to NSERC (Canada). MFC was supported by NASA under award number 80GSFC21M0002. We thank the referee A Mehner for many constructive criticisms. Data Availability: The data underlying this article are available in the article and in its supplementary material. Full Tables A2–A5 are available at CDS via anonymous ftp to ( or via
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)2011/51680-6
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)2019/02029-2
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)2017/18191-8
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:stars: binaries – stars: individual: eta Carinae – stars: winds – ISM: dust, extinction – ISM: molecules
Issue or Number:1
Record Number:CaltechAUTHORS:20210803-212512800
Persistent URL:
Official Citation:A Damineli, F Navarete, D J Hillier, A F J Moffat, M F Corcoran, T R Gull, N D Richardson, G Weigelt, P W Morris, I Stevens, Spectroscopic signatures of the vanishing natural coronagraph of Eta Carinae, Monthly Notices of the Royal Astronomical Society, Volume 505, Issue 1, July 2021, Pages 963–978,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110141
Deposited By: Tony Diaz
Deposited On:04 Aug 2021 18:55
Last Modified:04 Aug 2021 18:55

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