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Eta Carinae: A Tale of Two Periastron Passages

Gull, Theodore R. and Navarete, Felipe and Corcoran, Michael F. and Damineli, Augusto and Espinoza, David and Hamaguchi, Kenji and Hartman, Henrik and Hillier, D. John and Madura, Thomas and Moffat, Anthony F. J. and Morris, Patrick and Nielsen, Krister and Pittard, Julian M. and Pollock, Andrew M. T. and Richardson, Noel D. and Russell, Christopher M. P. and Stevens, Ian R. and Weigelt, Gerd (2021) Eta Carinae: A Tale of Two Periastron Passages. Astrophysical Journal, 923 (1). Art. No. 102. ISSN 0004-637X. doi:10.3847/1538-4357/ac22a6.

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Since 2002, the far-ultraviolet (FUV) flux (1150–1680 Å) of Eta Carinae, monitored by the Hubble Space Telescope/Space Telescope Imaging Spectrograph, has increased by an order of magnitude. This increase is attributed to partial dissipation of a line-of-sight (LOS) occulter that blocks the central core of the system. Across the 2020 February periastron passage, changes in the FUV emission show a stronger wavelength dependence than occurred across the 2003 July periastron passage. Across both periastron passages, most of the FUV spectrum dropped in flux then recovered a few months later. The 2020 periastron passage included enhancements of FUV flux in narrow spectral intervals near periastron followed by a transient absorption and recovery to pre-periastron flux levels. The drop in flux is due to increased absorption by singly ionized species as the secondary star plunges deep into the wind of the primary star, which blocks the companion’s ionizing radiation. The enhanced FUV emission is caused by the companion’s wind-blown cavity briefly opening a window to deeper layers of the primary star. This is the first time transient brightening has been seen in the FUV comparable to transients previously seen at longer wavelengths. Changes in resonance line-velocity profiles hint that the dissipating occulter is associated with material in LOS moving at −100 to −300 km s⁻¹, similar in velocity of structures previously associated with the 1890s lesser eruption.

Item Type:Article
Related URLs:
URLURL TypeDescription
Gull, Theodore R.0000-0002-6851-5380
Navarete, Felipe0000-0002-0284-0578
Corcoran, Michael F.0000-0002-7762-3172
Damineli, Augusto0000-0002-7978-2994
Hamaguchi, Kenji0000-0001-7515-2779
Hartman, Henrik0000-0001-9853-2555
Moffat, Anthony F. J.0000-0002-4333-9755
Morris, Patrick0000-0002-5186-4381
Nielsen, Krister0000-0003-2636-7663
Pittard, Julian M.0000-0003-2244-5070
Pollock, Andrew M. T.0000-0002-5725-7072
Richardson, Noel D.0000-0002-2806-9339
Stevens, Ian R.0000-0001-7673-4340
Weigelt, Gerd0000-0001-9754-2233
Additional Information:© 2021. The American Astronomical Society. Received 2021 June 4; revised 2021 August 27; accepted 2021 August 30; published 2021 December 14. We thank the referee for much effort and useful comments that improved the presentation especially for those less familiar with η Car. We acknowledge funding from HST programs 15611 and 15992, which were accepted as supplementary observations associated with Chandra X-ray Observatory programs 20200564 and 21200197. M.F.C. is supported under the CRESST-II cooperative agreement #80GSFC17M0002 with the NASA/Goddard Space Flight Center. A.D. received funding from FAPESP 2019/02029-2. F.N. acknowledges FAPESP for support through process 2017/18191-8. A.J.F.M. is grateful for financial aid from NSERC (Canada). Facility: HST(STIS). -
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Hubble FellowshipGO-15611
NASA Hubble FellowshipGO-15992
Fundação de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP)2019/02029-2
Fundação de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP)2017/18191-8
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:Massive stars; Stellar winds; Binary stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Massive stars (732); Stellar winds (1636); Binary stars (154)
Record Number:CaltechAUTHORS:20220107-81089900
Persistent URL:
Official Citation:Theodore R. Gull et al 2021 ApJ 923 102
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112781
Deposited By: Tony Diaz
Deposited On:09 Jan 2022 00:07
Last Modified:09 Jan 2022 22:05

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