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Mid-infrared evolution of η Carinae from 1968 to 2018

Mehner, A. and de Wit, W.-J. and Asmus, D. and Morris, P. W. and Agliozzo, C. and Barlow, M. J. and Gull, T. R. and Hillier, D. J. and Weigelt, G. (2019) Mid-infrared evolution of η Carinae from 1968 to 2018. Astronomy and Astrophysics, 630 . Art. No. L6. ISSN 0004-6361. doi:10.1051/0004-6361/201936277.

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η Car is one of the most luminous and massive stars in our Galaxy and is the brightest mid-IR source in the sky outside our solar system. Since the late 1990s, the central source has dramatically brightened at UV and optical wavelengths. This might be explained by a decrease in circumstellar dust extinction. We aim to establish the mid-IR flux evolution and further our understanding of the star’s UV and optical brightening. Mid-IR images from 8−20 μm were obtained in 2018 with VISIR at the Very Large Telescope. Archival data from 2003 and 2005 were retrieved from the ESO Science Archive Facility, and historical records were collected from publications. We present mid-IR images of η Car with the highest angular resolution to date at the corresponding wavelengths (≥0.22″). We reconstruct the mid-IR evolution of the spectral energy distribution of the spatially integrated Homunculus nebula from 1968 to 2018 and find no long-term changes. The bolometric luminosity of η Car has been stable over the past five decades. We do not observe a long-term decrease in the mid-IR flux densities that could be associated with the brightening at UV and optical wavelengths, but circumstellar dust must be declining in our line of sight alone. Short-term flux variations within about 25% of the mean levels could be present.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Mehner, A.0000-0002-9564-3302
Asmus, D.0000-0003-0220-2063
Agliozzo, C.0000-0003-1749-2542
Alternate Title:Mid-infrared evolution of eta Car from 1968 to 2018
Additional Information:© 2019 ESO. Article published by EDP Sciences. Received 9 July 2019; Accepted 23 August 2019; Published online 30 September 2019. We thank the anonymous referee for the constructive feedback. MJB acknowledges support from ERC grant SNDUST 694520. We have used SketchAndCalc to calculate the areas in isophotal contour maps (E. M. Dobbs;
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)694520
Subject Keywords:circumstellar matter – stars: individual: η Car – stars: massive – stars: mass-loss – stars: variables: S Doradus – stars: winds, outflows
Record Number:CaltechAUTHORS:20191018-084050524
Persistent URL:
Official Citation:Mid-infrared evolution of η Carinae from 1968 to 2018. A. Mehner, W.-J. de Wit, D. Asmus, P. W. Morris, C. Agliozzo, M. J. Barlow, T. R. Gull, D. J. Hillier and G. Weigelt. A&A, 630 (2019) L6. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99349
Deposited By: Tony Diaz
Deposited On:19 Oct 2019 04:24
Last Modified:16 Nov 2021 17:45

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