Light Echoes From Η Carinae's Great Eruption: Spectrophotometric Evolution and the Rapid Formation of Nitrogen-Rich Molecules

Prieto, J. L.; Rest, A.; Bianco, Federica; Matheson, T.; Smith, Nathan; Walborn, N. R.; Hsiao, E. Y.; Chornock, R.; Paredes, Leonardo A.; Campillay, A.; Contreras, C.; González, C.; James, D. J.; Knapp, G. R.; Kunder, Andrea; Margheim, Steve; Morrell, N.; Phillips, M. M.; Smith, R. C.; Welch, D. L.; Zenteno, A.

doi:10.1088/2041-8205/787/1/l8

Cited by 36 publications

(47 citation statements)

References 53 publications

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“…Indeed, in addition to the low spectral temperature, Rest et al (2012) and a follow up study of the light echoes by Prieto et al (2014), provide several additional arguments against a steady wind and in favor of an explosive origin of η Carinae's giant eruption. Similar and additional arguments (Smith et al 2010(Smith et al , 2011Smith 2014) favoring an explosive scenario have also been given for the broader population of giant-eruption LBVs.…”

Section: Concluding Discussionmentioning

confidence: 96%

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

Owocki¹,

Shaviv²

2016

Mon. Not. R. Astron. Soc.

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The detection by Rest et al. (2012) of light echoes from η Carinae has provided important new observational constraints on the nature of its 1840's era giant eruption. Spectra of the echoes suggest a relatively cool spectral temperature of about 5500K, lower than the lower limit of about 7000K suggested in the optically thick wind outflow analysis of Davidson (1987). This has lead to a debate about the viability of this steady wind model relative to alternative, explosive scenarios. Here we present an updated analysis of the wind outflow model using newer low-temperature opacity tabulations and accounting for the stronger mass loss implied by the >10 Msun mass now inferred for the Homunculus. A major conclusion is that, because of the sharp drop in opacity due to free electron recombination for T <6500K, a low temperature of about 5000K is compatible with, and indeed expected from, a wind with the extreme mass loss inferred for the eruption. Within a spherical gray model in radiative equilibrium, we derive spectral energy distributions for various assumptions for the opacity variation of the wind, providing a basis for comparisons with observed light echo spectra. The scaling results here are also potentially relevant for other highly optically thick outflows, including those from classical novae, giant eruptions of LBVs and SN Type IIn precursors. A broader issue therefore remains whether the complex, variable features observed from such eruptions are better understood in terms of a steady or explosive paradigm, or perhaps a balance of these idealizations.

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Section: Concluding Discussionmentioning

confidence: 96%

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

Owocki¹,

Shaviv²

2016

Mon. Not. R. Astron. Soc.

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“…Some giant eruptions do evolve to cooler temperature at peak, as in the case of light echoes from η Car (Rest et al 2012;Prieto et al 2014). Other cases remain uncertain; for example, we have no information about the temperature evolution in P Cygni's 1600-1650 CE eruption.…”

Section: The Hot Temperature and Bolometric Luminosity At Peakmentioning

confidence: 92%

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

Smith

Andrews

Moe

et al. 2020

Monthly Notices of the Royal Astronomical Society

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MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20 yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data reveal that this star brightened in 2010, with a light curve resembling that of the classic LBV star AF And in M31. Other Ofpe/WN9 stars have erupted as LBVs, but MCA-1B was unusual because it remained hot. It showed a WN-type spectrum throughout its eruption, whereas LBVs usually get much cooler. MCA-1B showed an almost four-fold increase in bolometric luminosity and a doubling of its radius, but its temperature stayed 29 kK. As it faded, it shifted to even hotter temperatures, exhibiting a WN7/WN8-type spectrum, and doubling its wind speed. MCA-1B is reminiscent of some supernova impostors, and its location resembles the isolated environment of SN 2009ip. It is most similar to HD 5980 (in the Small Magellanic Cloud) and GR 290 (also in M33). Whereas these two LBVs exhibited B-type spectra in eruption, MCA-1B is the first clear case where a Wolf-Rayet (WR) spectrum persisted at all times. Together, MCA-1B, HD 5980, and GR 290 constitute a class of WN-type LBVs, distinct from S Doradus LBVs. They are most interesting in the context of LBVs at low metallicity, a possible post-LBV/WR transition in binaries, and as likely Type Ibn supernova progenitors.

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“…Also, bolometric luminosities during SDor eruptions are not necessarily constant (Groh et al 2009a). Similarly, the idea that giant-eruption maxima are caused by pseudo-photospheres in super-Eddington winds is challenged by light-echo spectra of ηCarinae (Rest et al 2012;Prieto et al 2014; although see Owocki & Shaviv 2016), by detailed analysis of the ejecta around η Car that are better matched by an explosive event (Smith 2006b(Smith , 2008(Smith , 2013, and the fact that many extragalactic giant LBV eruptions are relatively hot, rather than cool, at peak luminosity (Smith et al 2011;Mauerhan et al 2015). Last, as discussed by Smith & Tombleson (2015), their isolation from massive O-type stars suggests that they are much older than expected.…”

Section: Introductionmentioning

confidence: 99%

The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 Are Much Closer than Previously Assumed

Smith

Stassun

2017

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The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and space motions of four canonical Milky Way LBVs-AGCar, HRCar, HD168607, and (candidate) Hen3-519-from the Gaia first data release. Whereas the distances of HRCar and HD168607 are consistent with previous literature estimates within the considerable uncertainties, Hen3-519 and AGCar, both at ∼2 kpc, are much closer than the 6-8 kpc distances previously assumed. As a result, Hen3-519 moves far from the locus of LBVs on the Hertzsprung-Russell diagram, making it a much less luminous object. For AGCar, considered a defining example of a classical LBV, its lower luminosity would also move it off the SDor instability strip. Lower luminosities allow both AGCar and Hen3-519 to have passed through a previous red supergiant phase, lower the mass estimates for their shell nebulae, and imply that binary evolution is needed to account for their peculiarities. These results may also impact our understanding of LBVs as potential supernova progenitors and their isolated environments. Improved distances will be provided in the Gaia second data release, which will include additional LBVs. AGCar and Hen3-519 hint that this new information may alter our traditional view of LBVs.

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Light Echoes From Η Carinae's Great Eruption: Spectrophotometric Evolution and the Rapid Formation of Nitrogen-Rich Molecules

Cited by 36 publications

References 53 publications

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

The spectral temperature of optically thick outflows with application to light echo spectra from η Carinae's giant eruption

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

The Canonical Luminous Blue Variable AG Car and Its Neighbor Hen 3-519 Are Much Closer than Previously Assumed

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