On the Radial Onset of Clumping in the Wind of the B0i Massive Star Qv Nor

Torrejón, José M.; Schulz, Norbert S.; Nowak, M. A.; Oskinova, L. M.; Roca, José Joaquín Rodes; Shenar, T.; Wilms, J.

doi:10.1088/0004-637x/810/2/102

Cited by 25 publications

(24 citation statements)

References 53 publications

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“…We note that other studies suggest clumping may already initiate at the photosphere (e.g. Cantiello et al 2009;Torrejón et al 2015). Clumping factors for the O companions, which cannot be deduced from the available spectra, are fixed to D = 10, supported by hydrodynamical simulations (Feldmeier et al 1997).…”

Section: Assumptionsmentioning

confidence: 52%

Wolf-Rayet stars in the Small Magellanic Cloud

Shenar

Hainich

Todt

et al. 2016

A&A

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103

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Context. Massive Wolf-Rayet (WR) stars are evolved massive stars (M i 20 M ) characterized by strong mass-loss. Hypothetically, they can form either as single stars or as mass donors in close binaries. About 40% of all known WR stars are confirmed binaries, raising the question as to the impact of binarity on the WR population. Studying WR binaries is crucial in this context, and furthermore enable one to reliably derive the elusive masses of their components, making them indispensable for the study of massive stars. Aims. By performing a spectral analysis of all multiple WR systems in the Small Magellanic Cloud (SMC), we obtain the full set of stellar parameters for each individual component. Mass-luminosity relations are tested, and the importance of the binary evolution channel is assessed. Methods. The spectral analysis is performed with the Potsdam Wolf-Rayet (PoWR) model atmosphere code by superimposing model spectra that correspond to each component. Evolutionary channels are constrained using the Binary Population and Spectral Synthesis (BPASS) evolution tool. Results. Significant hydrogen mass fractions (0.1 < X H < 0.4) are detected in all WN components. A comparison with massluminosity relations and evolutionary tracks implies that the majority of the WR stars in our sample are not chemically homogeneous. The WR component in the binary AB 6 is found to be very luminous (log L ≈ 6.3 [L ]) given its orbital mass (≈10 M ), presumably because of observational contamination by a third component. Evolutionary paths derived for our objects suggest that Roche lobe overflow had occurred in most systems, affecting their evolution. However, the implied initial masses ( 60 M ) are large enough for the primaries to have entered the WR phase, regardless of binary interaction. Conclusions. Together with the results for the putatively single SMC WR stars, our study suggests that the binary evolution channel does not dominate the formation of WR stars at SMC metallicity.

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Section: Assumptionsmentioning

confidence: 52%

Wolf-Rayet stars in the Small Magellanic Cloud

Shenar

Hainich

Todt

et al. 2016

A&A

Self Cite

103

166

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“…In Vela X-1, clumpy winds can reconcile the discrepancies between different estimates of the massloss rate (Sako et al 1999). Several lines of evidence also point towards the presence of wind clumping very close to the photosphere of O/B stars (Cohen et al 2011;Sundqvist & Owocki 2013;Torrejón et al 2015), well within the ∼1.7 R HD 77581 distance between the neutron star and HD 77581 in Vela X-1.…”

Section: The Source Of Varying Absorption Column Densitymentioning

confidence: 91%

The clumpy absorber in the high-mass X-ray binary Vela X-1

Grinberg

Hell

Mellah

et al. 2017

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Bright and eclipsing, the high-mass X-ray binary Vela X-1 offers a unique opportunity to study accretion onto a neutron star from clumpy winds of O/B stars and to disentangle the complex accretion geometry of these systems. In Chandra-HETGS spectroscopy at orbital phase ∼0.25, when our line of sight towards the source does not pass through the large-scale accretion structure such as the accretion wake, we observe changes in overall spectral shape on timescales of a few kiloseconds. This spectral variability is, at least in part, caused by changes in overall absorption and we show that such strongly variable absorption cannot be caused by unperturbed clumpy winds of O/B stars. We detect line features from high and low ionization species of silicon, magnesium and neon whose strengths and presence depend on the overall level of absorption. They imply a co-existence of cool and hot gas phases in the system that we interpret as a highly variable, structured accretion flow close to the compact object such as has been recently seen in simulations of wind accretion in high-mass X-ray binaries.

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“…The density in the clumps is enhanced by a factor D compared to a homogeneous wind with the same mass-loss rate, while the interclump space is assumed to be void. There are indications that clumps exist already at or very close to the photosphere (Cantiello et al 2009;Torrejón et al 2015). However, we assume that the clumping factor grows from 1 (unclumped) at the photosphere and reaches its maximum…”

Section: Powr Model Atmospheresmentioning

confidence: 99%

The extreme O-type spectroscopic binary HD 93129A

Gruner

Hainich

Sander

et al. 2019

A&A

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Context. HD 93129A was classified as the earliest O-type star in the Galaxy (O2 If*) and is considered as the prototype of its spectral class. However, interferometry shows that this object is a binary system, while recent observations even suggest a triple configuration. None of the previous spectral analyses of this object accounted for its multiplicity. With new high-resolution UV and optical spectra, we have the possibility to reanalyze this key object, taking its binary nature into account for the first time. Aims. We aim to derive the fundamental parameters and the evolutionary status of HD 93129A, identifying the contributions of both components to the composite spectrum Methods. We analyzed UV and optical observations acquired with the Hubble Space Telescope and ESO’s Very Large Telescope. A multiwavelength analysis of the system was performed using the latest version of the Potsdam Wolf-Rayet model atmosphere code. Results. Despite the similar spectral types of the two components, we are able to find signatures from each of the components in the combined spectrum, which allows us to estimate the parameters of both stars. We derive log(L∕L⊙) = 6.15, Teff = 52 kK, and log Ṁ = −4.7 [M⊙ yr−1] for the primary Aa, and log(L∕L⊙) = 5.58, Teff = 45 kK, and log Ṁ = −5.8 [M⊙yr−1] for the secondary Ab. Conclusions. Even when accounting for the binary nature, the primary of HD 93129A is found to be one of the hottest and most luminous O stars in our Galaxy. Based on the theoretical decomposition of the spectra, we assign spectral types O2 If* and O3 III(f*) to components Aa and Ab, respectively. While we achieve a good fit for a wide spectral range, specific spectral features are not fully reproduced. The data are not sufficient to identify contributions from a hypothetical third component in the system.

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On the Radial Onset of Clumping in the Wind of the B0i Massive Star Qv Nor

Cited by 25 publications

References 53 publications

Wolf-Rayet stars in the Small Magellanic Cloud

Wolf-Rayet stars in the Small Magellanic Cloud

The clumpy absorber in the high-mass X-ray binary Vela X-1

The extreme O-type spectroscopic binary HD 93129A

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