TY  - JOUR
A1  - El Mellah, Ileyk
A1  - Sander, Andreas Alexander Christoph
A1  - Sundqvist, Jon Olof
A1  - Keppens, Rony
T1  - Formation of wind-captured disks in supergiant X-ray binaries Consequences for Vela X-1 and Cygnus X-1
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. In supergiant X-ray binaries (SgXB), a compact object captures a fraction of the wind of an O/B supergiant on a close orbit. Proxies exist to evaluate the efficiency of mass and angular momentum accretion, but they depend so dramatically on the wind speed that given the current uncertainties, they only set loose constraints. Furthermore, these proxies often bypass the impact of orbital and shock effects on the flow structure. Aims. We study the wind dynamics and angular momentum gained as the flow is accreted. We identify the conditions for the formation of a disk-like structure around the accretor and the observational consequences for SgXB. Methods. We used recent results on the wind launching mechanism to compute 3D streamlines, accounting for the gravitational and X-ray ionizing influence of the compact companion on the wind. Once the flow enters the Roche lobe of the accretor, we solved the hydrodynamics equations with cooling. Results. A shocked region forms around the accretor as the flow is beamed. For wind speeds on the order of the orbital speed, the shock is highly asymmetric compared to the axisymmetric bow shock obtained for a purely planar homogeneous flow. With net radiative cooling, the flow always circularizes for sufficiently low wind speeds. Conclusions. Although the donor star does not fill its Roche lobe, the wind can be significantly beamed and bent by the orbital effects. The net angular momentum of the accreted flow is then sufficient to form a persistent disk-like structure. This mechanism could explain the proposed limited outer extension of the accretion disk in Cygnus X-1 and suggests the presence of a disk at the outer rim of the neutron star magnetosphere in Vela X-1 and has dramatic consequences on the spinning up of the accretor.
KW  - accretion, accretion disks
KW  - X-rays: binaries
KW  - stars: black holes
KW  - stars: neutron
KW  - supergiants
KW  - stars: winds, outflows
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201834498
SN  - 1432-0746
VL  - 622
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Sander, Andreas Alexander Christoph
A1  - Vink, Jorick S.
A1  - Hamann, Wolf-Rainer
T1  - Driving classical Wolf-Rayet winds
BT  - a Gamma- and Z-dependent mass-loss
JF  - Monthly notices of the Royal Astronomical Society
N2  - Classical Wolf-Rayet (cWR) stars are at a crucial evolutionary stage for constraining the fates of massive stars. The feedback of these hot, hydrogen-depleted stars dominates their surrounding by tremendous injections of ionizing radiation and kinetic energy. The strength of a Wolf-Rayet (WR) wind decides the eventual mass of its remnant, likely a massive black hole. However, despite their major influence and importance for gravitational wave detection statistics, WR winds are particularly poorly understood. In this paper, we introduce the first set of hydrodynamically consistent stellar atmosphere models for cWR stars of both the carbon (C) and the nitrogen (N) sequence, i.e. WC and WN stars, as a function of stellar luminosity-to-mass ratio (or Eddington Gamma) and metallicity. We demonstrate the inapplicability of the CAK wind theory for cWR stars and confirm earlier findings that their winds are launched at the (hot) iron (Fe) opacity peak. For log Z/Z(circle dot) > -2, Fe is also the main accelerator throughout the wind. Contrasting previous claims of a sharp lower mass-loss limit forWR stars, we obtain a smooth transition to optically thin winds. Furthermore, we find a strong dependence of the mass-loss rates on Eddington Gamma, both at solar and subsolar metallicity. Increases inWCcarbon and oxygen abundances turn out to slightly reduce the predicted mass-loss rates. Calculations at subsolar metallicities indicate that below the metallicity of the Small Magellanic Cloud, WR mass-loss rates decrease much faster than previously assumed, potentially allowing for high black hole masses even in the local Universe.
KW  - stars: atmospheres
KW  - stars: early-type
KW  - stars: fundamental parameters
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: Wolf-Rayet
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz3064
SN  - 0035-8711
SN  - 1365-2966
VL  - 491
IS  - 3
SP  - 4406
EP  - 4425
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kubatova, Brankica
A1  - Szecsi, D.
A1  - Sander, Andreas Alexander Christoph
A1  - Kubat, Jiří
A1  - Tramper, F.
A1  - Krticka, Jiri
A1  - Kehrig, C.
A1  - Hamann, Wolf-Rainer
A1  - Hainich, Rainer
A1  - Shenar, Tomer
T1  - Low-metallicity massive single stars with rotation
BT  - II. Predicting spectra and spectral classes of chemically homogeneously evolving stars
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Metal-poor massive stars are assumed to be progenitors of certain supernovae, gamma-ray bursts, and compact object mergers that might contribute to the early epochs of the Universe with their strong ionizing radiation. However, this assumption remains mainly theoretical because individual spectroscopic observations of such objects have rarely been carried out below the metallicity of the Small Magellanic Cloud. Aims. Here we explore the predictions of the state-of-the-art theories of stellar evolution combined with those of stellar atmospheres about a certain type of metal-poor (0.02 Z(circle dot)) hot massive stars, the chemically homogeneously evolving stars that we call Transparent Wind Ultraviolet INtense (TWUIN) stars. Methods. We computed synthetic spectra corresponding to a broad range in masses (20 130 M-circle dot) and covering several evolutionary phases from the zero-age main-sequence up to the core helium-burning stage. We investigated the influence of mass loss and wind clumping on spectral appearance and classified the spectra according to the Morgan-Keenan (MK) system. Results. We find that TWUIN stars show almost no emission lines during most of their core hydrogen-burning lifetimes. Most metal lines are completely absent, including nitrogen. During their core helium-burning stage, lines switch to emission, and even some metal lines (oxygen and carbon, but still almost no nitrogen) are detected. Mass loss and clumping play a significant role in line formation in later evolutionary phases, particularly during core helium-burning. Most of our spectra are classified as an early-O type giant or supergiant, and we find Wolf-Rayet stars of type WO in the core helium-burning phase. Conclusions. An extremely hot, early-O type star observed in a low-metallicity galaxy could be the result of chemically homogeneous evolution and might therefore be the progenitor of a long-duration gamma-ray burst or a type Ic supernova. TWUIN stars may play an important role in reionizing the Universe because they are hot without showing prominent emission lines during most of their lifetime.
KW  - stars: massive
KW  - stars: winds, outflows
KW  - stars: rotation
KW  - galaxies: dwarf
KW  - radiative transfer
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201834360
SN  - 1432-0746
SN  - 0004-6361
VL  - 623
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Shenar, Tomer
A1  - Sablowski, D. P.
A1  - Hainich, Rainer
A1  - Todt, Helge Tobias
A1  - Moffat, Anthony F. J.
A1  - Oskinova, Lida
A1  - Ramachandran, Varsha
A1  - Sana, Hugues
A1  - Sander, Andreas Alexander Christoph
A1  - Schnurr, O.
A1  - St-Louis, N.
A1  - Vanbeveren, D.
A1  - Gotberg, Y.
A1  - Hamann, Wolf-Rainer
T1  - The Wolf-Rayet binaries of the nitrogen sequence in the Large Magellanic Cloud Spectroscopy, orbital analysis, formation, and evolution
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Massive Wolf-Rayet (WR) stars dominate the radiative and mechanical energy budget of galaxies and probe a critical phase in the evolution of massive stars prior to core collapse. It is not known whether core He-burning WR stars (classical WR; cWR) form predominantly through wind stripping (w-WR) or binary stripping (b-WR). Whereas spectroscopy of WR binaries has so-far largely been avoided because of its complexity, our study focuses on the 44 WR binaries and binary candidates of the Large Magellanic Cloud (LMC; metallicity Z approximate to 0.5 Z(circle dot)), which were identified on the basis of radial velocity variations, composite spectra, or high X-ray luminosities. Aims. Relying on a diverse spectroscopic database, we aim to derive the physical and orbital parameters of our targets, confronting evolution models of evolved massive stars at subsolar metallicity and constraining the impact of binary interaction in forming these stars. Methods. Spectroscopy was performed using the Potsdam Wolf-Rayet (PoWR) code and cross-correlation techniques. Disentanglement was performed using the code Spectangular or the shift-and-add algorithm. Evolutionary status was interpreted using the Binary Population and Spectral Synthesis (BPASS) code, exploring binary interaction and chemically homogeneous evolution. Results. Among our sample, 28/44 objects show composite spectra and are analyzed as such. An additional five targets show periodically moving WR primaries but no detected companions (SB1); two (BAT99 99 and 112) are potential WR + compact-object candidates owing to their high X-ray luminosities. We cannot confirm the binary nature of the remaining 11 candidates. About two-thirds of the WN components in binaries are identified as cWR, and one-third as hydrogen-burning WR stars. We establish metallicity-dependent mass-loss recipes, which broadly agree with those recently derived for single WN stars, and in which so-called WN3/O3 stars are clear outliers. We estimate that 45 +/- 30% of the cWR stars in our sample have interacted with a companion via mass transfer. However, only approximate to 12 +/- 7% of the cWR stars in our sample naively appear to have formed purely owing to stripping via a companion (12% b-WR). Assuming that apparently single WR stars truly formed as single stars, this comprises approximate to 4% of the whole LMC WN population, which is about ten times less than expected. No obvious differences in the properties of single and binary WN stars, whose luminosities extend down to log L approximate to 5.2 [L-circle dot], are apparent. With the exception of a few systems (BAT99 19, 49, and 103), the equatorial rotational velocities of the OB-type companions are moderate (v(eq) less than or similar to 250 km s(-1)) and challenge standard formalisms of angular-momentum accretion. For most objects, chemically homogeneous evolution can be rejected for the secondary, but not for the WR progenitor. Conclusions. No obvious dichotomy in the locations of apparently single and binary WN stars on the Hertzsprung-Russell diagram is apparent. According to commonly used stellar evolution models (BPASS, Geneva), most apparently single WN stars could not have formed as single stars, implying that they were stripped by an undetected companion. Otherwise, it must follow that pre-WR mass-loss/mixing (e.g., during the red supergiant phase) are strongly underestimated in standard stellar evolution models.
KW  - stars: massive
KW  - stars: Wolf-Rayet
KW  - Magellanic Clouds
KW  - binaries: close
KW  - binaries: spectroscopic
KW  - stars: evolution
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201935684
SN  - 0004-6361
SN  - 1432-0746
VL  - 627
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Ramachandran, Varsha
A1  - Hamann, Wolf-Rainer
A1  - Oskinova, Lida
A1  - Gallagher, J. S.
A1  - Hainich, Rainer
A1  - Shenar, Tomer
A1  - Sander, Andreas Alexander Christoph
A1  - Todt, Helge Tobias
A1  - Fulmer, Leah M.
T1  - Testing massive star evolution, star formation history, and feedback at low metallicity
BT  - Spectroscopic analysis of OB stars in the SMC Wing
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Stars that start their lives with spectral types O and early B are the progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars, and black holes. These massive stars are the primary sources of stellar feedback in star-forming galaxies. At low metallicities, the properties of massive stars and their evolution are not yet fully explored. Here we report a spectroscopic study of 320 massive stars of spectral types O (23 stars) and B (297 stars) in the Wing of the Small Magellanic Cloud (SMC). The spectra, which we obtained with the ESO Very Large Telescope, were analyzed using state-of-the-art stellar atmosphere models, and the stellar parameters were determined. We find that the stellar winds of our sample stars are generally much weaker than theoretically expected. The stellar rotation rates show broad, tentatively bimodal distributions. The upper Hertzsprung-Russell diagram (HRD) is well populated by the stars of our sample from a specific field in the SMC Wing. A few very luminous O stars are found close to the main sequence, while all other, slightly evolved stars obey a strict luminosity limit. Considering additional massive stars in evolved stages, with published parameters and located all over the SMC, essentially confirms this picture. The comparison with single-star evolutionary tracks suggests a dichotomy in the fate of massive stars in the SMC. Only stars with an initial mass below similar to 30 M-circle dot seem to evolve from the main sequence to the cool side of the HRD to become a red supergiant and to explode as type II-P supernova. In contrast, stars with initially more than similar to 30 M-circle dot appear to stay always hot and might evolve quasi chemically homogeneously, finally collapsing to relatively massive black holes. However, we find no indication that chemical mixing is correlated with rapid rotation. We measured the key parameters of stellar feedback and established the links between the rates of star formation and supernovae. Our study demonstrates that in metal-poor environments stellar feedback is dominated by core-collapse supernovae in combination with winds and ionizing radiation supplied by a few of the most massive stars. We found indications of the stochastic mode of massive star formation, where the resulting stellar population is fully capable of producing large-scale structures such as the supergiant shell SMC-SGS 1 in the Wing. The low level of feedback in metal-poor stellar populations allows star formation episodes to persist over long timescales.
KW  - stars: evolution
KW  - stars: massive
KW  - stars: mass-loss
KW  - Magellanic Clouds
KW  - Hertzsprung-Russell and C-M diagrams
KW  - techniques: spectroscopic
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201935365
SN  - 1432-0746
VL  - 625
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Sander, Andreas Alexander Christoph
A1  - Hamann, Wolf-Rainer
A1  - Todt, Helge Tobias
A1  - Hainich, Rainer
A1  - Shenar, Tomer
A1  - Ramachandran, Varsha
A1  - Oskinova, Lida
T1  - The Galactic WC and WO stars
BT  - The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Wolf-Rayet stars of the carbon sequence (WC stars) are an important cornerstone in the late evolution of massive stars before their core collapse. As core-helium burning, hydrogen-free objects with huge mass-loss, they are likely the last observable stage before collapse and thus promising progenitor candidates for type Ib/c supernovae. Their strong mass-loss furthermore provides challenges and constraints to the theory of radiatively driven winds. Thus, the determination of the WC star parameters is of major importance for several astrophysical fields. With Gaia DR2, for the first time parallaxes for a large sample of Galactic WC stars are available, removing major uncertainties inherent to earlier studies. In this work, we re-examine a previously studied sample of WC stars to derive key properties of the Galactic WC population. All quantities depending on the distance are updated, while the underlying spectral analyzes remain untouched. Contrasting earlier assumptions, our study yields that WC stars of the same subtype can significantly vary in absolute magnitude. With Gaia DR2, the picture of the Galactic WC population becomes more complex: We obtain luminosities ranging from log L/L-circle dot = 4.9-6.0 with one outlier (WR 119) having log L/L-circle dot = 4.7. This indicates that the WC stars are likely formed from a broader initial mass range than previously assumed. We obtain mass-loss rates ranging between log(M) over dot = -5.1 and -4.1, with (M) over dot proportional to L-0.68 and a linear scaling of the modified wind momentum with luminosity. We discuss the implications for stellar evolution, including unsolved issues regarding the need of envelope inflation to address the WR radius problem, and the open questions in regard to the connection of WR stars with Gamma-ray bursts. WC and WO stars are progenitors of massive black holes, collapsing either silently or in a supernova that most-likely has to be preceded by a WO stage.
KW  - stars: evolution
KW  - stars: mass-loss
KW  - stars: Wolf-Rayet
KW  - stars: massive
KW  - stars: distances
KW  - Galaxy: stellar content
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201833712
SN  - 1432-0746
VL  - 621
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Hamann, Wolf-Rainer
A1  - Gräfener, G.
A1  - Liermann, A.
A1  - Hainich, Rainer
A1  - Sander, Andreas Alexander Christoph
A1  - Shenar, Tomer
A1  - Ramachandran, Varsha
A1  - Todt, Helge Tobias
A1  - Oskinova, Lida
T1  - The Galactic WN stars revisited
BT  - Impact of Gaia distances on fundamental stellar parameters
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Comprehensive spectral analyses of the Galactic Wolf-Rayet stars of the nitrogen sequence (i.e. the WN subclass) have been performed in a previous paper. However, the distances of these objects were poorly known. Distances have a direct impact on the "absolute" parameters, such as luminosities and mass-loss rates. The recent Gaia Data Release (DR2) of trigonometric parallaxes includes nearly all WN stars of our Galactic sample. In the present paper, we apply the new distances to the previously analyzed Galactic WN stars and rescale the results accordingly. On this basis, we present a revised catalog of 55 Galactic WN stars with their stellar and wind parameters. The correlations between mass-loss rate and luminosity show a large scatter, for the hydrogen-free WN stars as well as for those with detectable hydrogen. The slopes of the log L - log M correlations are shallower than found previously. The empirical Hertzsprung-Russell diagram (HRD) still shows the previously established dichotomy between the hydrogen-free early WN subtypes that are located on the hot side of the zero-age main sequence (ZAMS), and the late WN subtypes, which show hydrogen and reside mostly at cooler temperatures than the ZAMS (with few exceptions). However, with the new distances, the distribution of stellar luminosities became more continuous than obtained previously. The hydrogen-showing stars of late WN subtype are still found to be typically more luminous than the hydrogen-free early subtypes, but there is a range of luminosities where both subclasses overlap. The empirical HRD of the Galactic single WN stars is compared with recent evolutionary tracks. Neither these single-star evolutionary models nor binary scenarios can provide a fully satisfactory explanation for the parameters of these objects and their location in the HRD.
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: Wolf-Rayet
KW  - stars: atmospheres
KW  - stars: evolution
KW  - stars: distances
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201834850
SN  - 1432-0746
VL  - 625
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Hainich, Rainer
A1  - Ramachandran, Varsha
A1  - Shenar, Tomer
A1  - Sander, Andreas Alexander Christoph
A1  - Todt, Helge Tobias
A1  - Gruner, David
A1  - Oskinova, Lida
A1  - Hamann, Wolf-Rainer
T1  - PoWR grids of non-LTE model atmospheres for OB-type stars of various metallicities
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The study of massive stars in different metallicity environments is a central topic of current stellar research. The spectral analysis of massive stars requires adequate model atmospheres. The computation of such models is difficult and time-consuming. Therefore, spectral analyses are greatly facilitated if they can refer to existing grids of models. Here we provide grids of model atmospheres for OB-type stars at metallicities corresponding to the Small and Large Magellanic Clouds, as well as to solar metallicity. In total, the grids comprise 785 individual models. The models were calculated using the state-of-the-art Potsdam Wolf-Rayet (PoWR) model atmosphere code. The parameter domain of the grids was set up using stellar evolution tracks. For all these models, we provide normalized and flux-calibrated spectra, spectral energy distributions, feedback parameters such as ionizing photons, Zanstra temperatures, and photometric magnitudes. The atmospheric structures (the density and temperature stratification) are available as well. All these data are publicly accessible through the PoWR website.
KW  - stars: massive
KW  - stars: early-type
KW  - stars: atmospheres
KW  - stars: winds
KW  - outflows
KW  - stars: mass-loss
KW  - radiative transfer
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201833787
SN  - 1432-0746
VL  - 621
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Gruner, David
A1  - Hainich, Rainer
A1  - Sander, Andreas Alexander Christoph
A1  - Shenar, Tomer
A1  - Todt, Helge Tobias
A1  - Oskinova, Lida
A1  - Ramachandran, Varsha
A1  - Ayres, T.
A1  - Hamann, Wolf-Rainer
T1  - The extreme O-type spectroscopic binary HD 93129A A quantitative, multiwavelength analysis
JF  - Astronomy and astrophysics : an international weekly journal
N2  - 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 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-circle dot) = 6.15, T-eff = 52 kK, and log (M)over dot = -4.7[M-circle dot yr(-1)] for the primary Aa, and log(L/L-circle dot) = 5.58, T-eff = 45 kK, and log (M)over dot = -5.8 [M(circle dot)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.
KW  - stars: individual: HD 93129A
KW  - stars: atmospheres
KW  - stars: fundamental parameters
KW  - stars: early-typeP
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201833178
SN  - 1432-0746
VL  - 621
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Ramachandran, Varsha
A1  - Hamann, Wolf-Rainer
A1  - Hainich, Rainer
A1  - Oskinova, Lida
A1  - Shenar, Tomer
A1  - Sander, Andreas Alexander Christoph
A1  - Todt, Helge Tobias
A1  - Gallagher, John S.
T1  - Stellar population of the superbubble N206 in the LMC II. Parameters of the OB and WR stars, and the total massive star feedback
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Clusters or associations of early-type stars are often associated with a "superbubble" of hot gas. The formation of such superbubbles is caused by the feedback from massive stars. The complex N206 in the Large Magellanic Cloud (LMC) exhibits a superbubble and a rich massive star population. Aims. Our goal is to perform quantitative spectral analyses of all massive stars associated with the N206 superbubble in order to determine their stellar and wind parameters. We compare the superbubble energy budget to the stellar energy input and discuss the star formation history of the region. Results. We present the stellar and wind parameters of the OB stars and the two Wolf-Rayet (WR) binaries in the N206 complex. Twelve percent of the sample show Oe/Be type emission lines, although most of them appear to rotate far below critical. We found eight runaway stars based on their radial velocity. The wind-momentum luminosity relation of our OB sample is consistent with the expectations. The Hertzsprung-Russell diagram (HRD) of the OB stars reveals a large age spread (1-30 Myr), suggesting different episodes of star formation in the complex. The youngest stars are concentrated in the inner part of the complex, while the older OB stars are scattered over outer regions. We derived the present day mass function for the entire N206 complex as well as for the cluster NGC2018. The total ionizing photon flux produced by all massive stars in the N206 complex is Q(0) approximate to 5 x 10(50) s(-1), and the mechanical luminosity of their stellar winds amounts to L-mec = 1.7 x 10(38) erg s(-1). Three very massive Of stars are found to dominate the feedback among 164 OB stars in the sample. The two WR winds alone release about as much mechanical luminosity as the whole OB star sample. The cumulative mechanical feedback from all massive stellar winds is comparable to the combined mechanical energy of the supernova explosions that likely occurred in the complex. Accounting also for the WR wind and supernovae, the mechanical input over the last five Myr is approximate to 2.3 x 10(52) erg. Conclusions. The N206 complex in the LMC has undergone star formation episodes since more than 30 Myr ago. From the spectral analyses of its massive star population, we derive a current star formation rate of 2.2 x 10(-3) M-circle dot yr(-1). From the combined input of mechanical energy from all stellar winds, only a minor fraction is emitted in the form of X-rays. The corresponding input accumulated over a long time also exceeds the current energy content of the complex by more than a factor of five. The morphology of the complex suggests a leakage of hot gas from the superbubble.
KW  - stars: massive
KW  - Magellanic Clouds
KW  - stars: winds, outflows
KW  - Hertzsprung-Russell and C-M diagrams
KW  - techniques: spectroscopic
KW  - ISM: bubbles
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201832816
SN  - 1432-0746
VL  - 615
PB  - EDP Sciences
CY  - Les Ulis
ER  -