Mid-infrared imaging
 and spectroscopy of the enigmatic cocoon stars in the Quintuplet
 Cluster

Moneti, A.; Stolovy, S.; Blommaert, J. A. D. L.; Figer, Donald F.; Najarro, F.

doi:10.1051/0004-6361:20000192

Cited by 80 publications

(121 citation statements)

References 24 publications

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“…By interpolating the extinction law values of Moneti et al (2001), which result for λ > 2.5 µm from the modelisation of ISO SWS measurements (Lutz 1999), and using A K = 2.7 (Clénet et al 2001), we obtain A L = 1.30 and A M = 1.21. Dereddened fluxes are computed assuming zero magnitudes values from Cox (2000): F 0 (L ) = 248 Jy and F 0 (M ) = 160 Jy.…”

Section: Photometrymentioning

confidence: 96%

Detection of the Sgr A* activity at 3.8 and 4.8 $\mathsf{\mu}$m with NACO

Clénet¹,

Rouan²,

Gratadour³

et al. 2004

A&A

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Abstract. L -band (λ = 3.8 µm) and M -band (λ = 4.8 µm) observations of the Galactic Center region, performed in 2003 at VLT (ESO) with the adaptive optics imager NACO, have lead to the detection of an infrared counterpart of the radio source Sgr A* at both wavelengths. The measured fluxes confirm that the Sgr A* infrared spectrum is dominated by the synchrotron emission of nonthermal electrons. The infrared counterpart exhibits no significant short term variability but demonstrates flux variations on daily and yearly scales. The observed emission arises away from the position of the dynamical center of the S2 orbit and would then not originate from the closest regions of the black hole.

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Section: Photometrymentioning

confidence: 96%

Detection of the Sgr A* activity at 3.8 and 4.8 $\mathsf{\mu}$m with NACO

Clénet¹,

Rouan²,

Gratadour³

et al. 2004

A&A

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“…By default, the reddening law from Seaton (1979) is applied. It is augmented by interstellar Lα absorption in the UV and by the data from Moneti et al (2001) in the IR. In cases where Seaton's law does not allow us to reproduce the observed SED satisfactorily, we try to improve the fit with the help of anomalous reddening.…”

Section: The Spectral Energy Distributionmentioning

confidence: 99%

The Galactic WN stars

Hamann¹,

Gräfener²,

Liermann³

2006

A&A

352

578

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Context. Very massive stars pass through the Wolf-Rayet (WR) stage before they finally explode. Details of their evolution have not yet been safely established, and their physics are not well understood. Their spectral analysis requires adequate model atmospheres, which have been developed step by step during the past decades and account in their recent version for line blanketing by the millions of lines from iron and iron-group elements. However, only very few WN stars have been re-analyzed by means of line-blanketed models yet. Aims. The quantitative spectral analysis of a large sample of Galactic WN stars with the most advanced generation of model atmospheres should provide an empirical basis for various studies about the origin, evolution, and physics of the Wolf-Rayet stars and their powerful winds. Methods. We analyze a large sample of Galactic WN stars by means of the Potsdam Wolf-Rayet (PoWR) model atmospheres, which account for iron line blanketing and clumping. The results are compared with a synthetic population, generated from the Geneva tracks for massive star evolution. Results. We obtain a homogeneous set of stellar and atmospheric parameters for the Galactic WN stars, partly revising earlier results. Conclusions. Comparing the results of our spectral analyses of the Galactic WN stars with the predictions of the Geneva evolutionary calculations, we conclude that there is rough qualitative agreement. However, the quantitative discrepancies are still severe, and there is no preference for the tracks that account for the effects of rotation. It seems that the evolution of massive stars is still not satisfactorily understood.

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“…The Lutz law is also used in some particular cases like some dense H ii regions or some objects with a carbon-rich environment. As an example, Moneti et al (2001) used the Lutz law to deredden their 2.5-8 µm ISO data on the Quintuplet Cluster, although this young cluster is in the vicinity of the Galactic Centre. Indebetouw et al (2005) presented very recent extinction measurements in the 1.25-8.0 µm range along the l = 42 • and l = 284 • line of sight in the galactic plane, which are similar and consistent with measurements of Lutz et al (1996) toward the Galactic Centre.…”

Section: Dereddeningmentioning

confidence: 99%

SS 433: a phenomenon imitating a Wolf-Rayet star

Fuchs

Miramond

Ábrahám

2006

A&A

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We present mid-infrared (2-12 µm) spectra of the microquasar SS 433 obtained with the Infrared Space Observatory (spectroscopic mode of ISOPHOT and ISOCAM). We compare them to the spectra of four Wolf-Rayet stars: WR 78, WR 134, WR 136, and WR 147 in the same wavelength range. The mid-infrared spectrum of SS 433 mainly shows H i and He i emission lines and is very similar to the spectrum of WR 147, a WN8(h)+B0.5V binary. The 2-12 µm continuum emission of SS 433 corresponds to optically thin and partially optically thick free-free emission, from which we calculate a mass loss rate of 2−3 × 10 −4 M yr −1 if the wind is homogeneous and a third of these values if it is clumped. This is consistent with a strong stellar wind from a WN star. However, following recent studies concluding that the mass donor star of SS 433 is not a Wolf-Rayet star, we propose that this strong wind out flows from a geometrically thick envelope of material that surrounds the compact object like a stellar atmosphere, imitating the Wolf-Rayet phenomenon. This wind could also wrap the mass donor star, and at larger distances (∼40 AU), it might form a dust envelope from which the thermal emission, detected with ISOPHOT at 25 µm and 60 µm, would originate. This wind also probably feeds the material that is ejected in the orbital plane of the binary system and that forms the equatorial outflow detected in radio at distances > 100 AU.

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Mid-infrared imaging and spectroscopy of the enigmatic cocoon stars in the Quintuplet Cluster

Cited by 80 publications

References 24 publications

Detection of the Sgr A* activity at 3.8 and 4.8 $\mathsf{\mu}$m with NACO

Detection of the Sgr A* activity at 3.8 and 4.8 $\mathsf{\mu}$m with NACO

The Galactic WN stars

SS 433: a phenomenon imitating a Wolf-Rayet star

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