The spectral energy distribution and mass-loss history of IRC + 10420

Oudmaijer, R. D.; Groenewegen, M. A. T.; Matthews, H. E.; Blommaert, J. A. D. L.; Sahu, K. C.

doi:10.1093/mnras/280.4.1062

Cited by 75 publications

(112 citation statements)

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“…None of the YHGs in Wd 1 possess the old (∼4000 yr), massive (M > 1 M ) ejection nebulae seen in HD 179821 and IRC +10 420 (Oudmaijer et al 1996;Castro-Carrizo et al 2007). We suspect that in the extreme environment of Wd 1 such nebulae would quickly be ablated by the cluster wind arising from the OB stars -as appears to be the case for the RSGs W20 and W26 (see Sect.…”

Section: The Yellow Hypergiantsmentioning

confidence: 96%

Radio emission from the massive stars in the galactic super star cluster Westerlund 1

Dougherty

Clark

Negueruela

et al. 2010

A&A

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Aims. Current mass-loss rate estimates imply that main sequence line-driven winds are not sufficient to strip away the H-rich envelope to yield Wolf-Rayet (WR) stars. The rich transitional population of the young massive cluster Westerlund 1 (Wd 1) provides an ideal laboratory to observe and constrain mass-loss processes throughout the transitional phase of stellar evolution. Methods. We present an analysis of deep radio continuum observations of Wd 1 obtained with the Australia Telescope Compact Array at four frequency bands that permit investigation of the intrinsic characteristics of the radio emission. Results. We detect 18 cluster members, a sample dominated by the cool hypergiants, with additional detections amongst the hotter OB supergiants and WR stars. The radio properties of the sample are diverse, with thermal, non-thermal and composite thermal/nonthermal sources present. Mass-loss rates determined for stars with partially optically thick stellar winds are ∼10 −5 M yr −1 across all spectral types, insufficient to enable the formation of WRs during a massive star lifetime, and the stars must undergo a period of greatly enhanced mass loss. The sgB[e] star W9, the brightest radio source in Wd 1, may provide an example, with a current mass-loss rate an order of magnitude higher than the other cluster members, and an extended nebula interpreted as a wind from an earlier epoch with a density ∼3× the current wind. Such an envelope structure in W9 is reminiscent of luminous blue variables, and one that shows evidence of two eras of high, possibly eruptive mass loss. Surprisingly, three of the OB supergiants are detected, implying unusually dense winds, though they are embedded in more extended emission regions that may influence the derived parameters. They also may have composite spectra, suggesting binarity, which can lead to a higher flux than expected from a stellar wind. Spatially resolved nebulae are associated with three of the four RSGs and three of the six YHGs in the cluster, which are due to quiescent mass loss rather than outbursts. The extended nebulae of W20 and W26 have a cometary morphology, implying significant interaction with either the intracluster medium or cluster wind. For some of the cool star winds, the ionizing source may be a companion star though the cluster radiation density is sufficiently high to provide the necessary ionizing radiation. Five WR stars are detected with composite spectra, interpreted as arising in colliding-wind binaries.

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Section: The Yellow Hypergiantsmentioning

confidence: 96%

Radio emission from the massive stars in the galactic super star cluster Westerlund 1

Dougherty

Clark

Negueruela

et al. 2010

A&A

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“…A simple calculation shows that for a luminosity of IRC +10 420 of 25 462 (d/kpc) 2 L (Blöcker et al 1999) and a mid-A spectral type (Oudmaijer et al 1996), a stellar diameter of ∼0.70 mas can be expected (see Fig. 2).…”

Section: Amber Spectro-interferometrymentioning

confidence: 97%

“…Its distance of 3.5 to 5 kpc implies a luminosity typical for a star with an initial mass of around 40 M , which places it close to the Humphreys-Davidson limit in the Hertzsprung-Russell diagram (Jones et al 1993). The spectral type makes IRC +10 420 a member of the class of yellow hypergiants (de Jager 1998), while its infrared excess due to circumstellar dust indicates that it was only recently undergoing extreme mass-loss, presumably in the red supergiant phase (Oudmaijer et al 1996). The number of known post-red supergiants is very small, Oudmaijer et al (2009) …”

Section: Introductionmentioning

confidence: 95%

Neutral and ionised gas around the post-red supergiant IRC +10 420 at AU size scales

Oudmaijer

Wit

2013

A&A

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Context. IRC +10 420 is one of the few known massive stars in rapid transition from the red supergiant phase to the Wolf-Rayet or luminous blue variable phase. Aims. The star has an ionised wind and using the Brγ line we assess the mass-loss on spatial scales of ∼1 AU. Methods. We present new VLT Interferometer AMBER data which are combined with all other AMBER data present in the literature. The final dataset covers a position angle range of ∼180 • and baselines up to 110 m. The spectrally dispersed visibilities, differential phases and line flux are conjointly analysed and modelled. We also present the first AMBER/FINITO observations which cover a larger wavelength range and allow us to observe the Na i doublet at 2.2 μm. The data are complemented by X-Shooter data, which provide a higher spectral resolution view.Results. The Brγ emission line and the Na i doublet are both spatially resolved. After correcting the AMBER data for the fact that the lines are not spectrally resolved, we find that Brγ traces a ring with a diameter of 4.18 mas, in agreement with higher spectral resolution data. We consider a geometric model in which the Brγ emission emerges from the top and bottom rings of an hour-glass shaped structure, viewed almost pole-on. It provides satisfactory fits to most visibilities and differential phases. The fact that we detect line emission from a neutral metal like Na i within the ionised region, a very unusual occurrence, suggests the presence of a dense pseudo-photosphere. Conclusions. The ionised wind can be reproduced with a polar wind, which could well have the shape of an hour-glass. Closer in, the resolved Na i emission is found to occur on scales barely larger than the continuum. This fact and that many yellow hypergiants exhibit this comparatively rare emission hints at the presence of a "Yellow" or even "White Wall" in the Hertzsprung-Russell diagram, preventing them from visibly evolving to the blue.

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“…It is one of the brightest 10 -20/xm infrared sources in the sky and is also the warmest known OH maser. Its apparent brightness increased substantially from 1920 to 1970 and its apparent spectral type is thought to have changed from late F to mid-A-type during the past 30 years (Humphreys et al 1973;Oudmaijer et al 1996). Thus IRC+10420 is our best candidate for post-red supergiant evolution near the top of the HR diagram.…”

Section: What Is Irc+10420?mentioning

confidence: 97%

Crossing the “Yellow Void” – Spatially Resolved Spectroscopy of the Post–Red Supergiant IRC+10420

Humphreys

Davidson

Smith

2002

International Astronomical Union Colloquium

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Abstract. IRC+10420 is a post-red supergiant at the empirical luminosity boundary in the HR diagram. It has now reached a stage in its blueward evolution where increasing opacity and partial ionization destabilize its atmosphere leading to rapid mass loss. Indeed, its wind is so dense that it is opaque and hides the underlying star. We have obtained HST/STIS spectroscopy with spatial resolution good enough to separate the star from its complex ejecta with numerous arcs, knots and jet-like features. The ejecta form essentially a reflection nebula, allowing us to view the star from a range of directions. The kinematics of the ejecta cannot be reconciled with existing models with either an equatorial disk or a bipolar outflow. Therefore we propose a model with a uniform spherically symmetric outflow of gas with random, asymmetric ejections superimposed. In our model, local instabilities allow for inflowing and outflowing material to coexist.

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The spectral energy distribution and mass-loss history of IRC + 10420

Cited by 75 publications

References 0 publications

Radio emission from the massive stars in the galactic super star cluster Westerlund 1

Radio emission from the massive stars in the galactic super star cluster Westerlund 1

Neutral and ionised gas around the post-red supergiant IRC +10 420 at AU size scales

Crossing the “Yellow Void” – Spatially Resolved Spectroscopy of the Post–Red Supergiant IRC+10420

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