High-resolution imaging of Galactic massive stars with AstraLux

Apellániz, J. Maíz

doi:10.1051/0004-6361/201014409

Cited by 61 publications

(44 citation statements)

References 33 publications

(54 reference statements)

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“…3, but component B was clearly separated from A in the processed data in all cases (Aa and Ab components cannot be separated with lucky imaging). The first epoch was discussed by Maíz Apellániz (2010), where the reader is referred for further details on the data.…”

Section: Observationsmentioning

confidence: 99%

ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

Simón‐Díaz

Caballero

Lorenzo

et al. 2015

ApJ

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We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code fastwind. We used our own plus other available information on photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code bonnsai. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the σ Ori Aa, Ab pair. We provided indirect arguments indicating that σ Ori B is a fast-rotating early B dwarf. The fastwind+bonnsai analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while σ Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the σ Orionis cluster, at 3 ± 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the σ Orionis cluster, the interpretation of the strong X-ray emission detected for σ Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects.

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Section: Observationsmentioning

confidence: 99%

ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

Simón‐Díaz

Caballero

Lorenzo

et al. 2015

ApJ

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“…(5) Lastly, stellar multiplicity seems to play a fundamental role in the context of massive stars, significantly affecting their evolution (e.g., Eldridge et al 2013). Several studies in the past years (e.g., Mason et al 2009;Maíz Apellániz 2010;Chini et al 2012;Sana et al 2013;Sota et al 2014;Aldoretta et al 2014) give direct evidence that at least half of the massive stars are found in multiple systems. Massive stars in close binary systems generally evolve differently from single stars.…”

Section: Introductionmentioning

confidence: 99%

A COORDINATED X-RAY AND OPTICAL CAMPAIGN OF THE NEAREST MASSIVE ECLIPSING BINARY,δORIONIS Aa. IV. A MULTIWAVELENGTH, NON-LTE SPECTROSCOPIC ANALYSIS

Shenar

Oskinova

Hamann

et al. 2015

ApJ

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263

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Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system.The primary's distance-independent parameters turn out to be characteristic for its spectral type (O9.5 II), but usage of the Hipparcos parallax yields surprisingly low values for the mass, radius, and luminosity. Consistent values follow only if δ Ori lies at about twice the Hipparcos distance, in the vicinity of the σ-Orionis cluster. The primary and tertiary dominate the spectrum and leave the secondary only marginally detectable. We estimate the V-band magnitude difference between primary and secondary to be ∆V ≈ 2. m 8. The inferred parameters suggest the secondary is an early B-type dwarf (≈ B1 V), while the tertiary is an early B-type subgiant (≈ B0 IV). We find evidence for rapid turbulent velocities (∼ 200 km s −1 ) and wind inhomogeneities, partially optically thick, in the primary's wind. The bulk of the X-ray emission likely emerges from the primary's stellar wind (log L X /L Bol ≈ −6.85), initiating close to the stellar surface at R 0 ∼ 1.1 R * . Accounting for clumping, the mass-loss rate of the primary is found to be logṀ ≈ −6.4 [M ⊙ yr −1 ] , which agrees with hydrodynamic predictions, and provides a consistent picture along the X-ray, UV, optical and radio spectral domains.

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“…This is in accord with a recent spectroscopic survey finding that among ∼240 southern Galactic O and WN stars more than 100 stars show radial velocity (RV) variations larger than 10 km s −1 (Barbá et al ). Recently, a high‐resolution imaging campaign of 138 fields containing at least one high‐mass star yielded a multiplicity fraction close to 50 per cent (Maíz‐Apellániz ). In summary, the spectroscopic binary frequency of high‐mass stars so far observed and reported in the literature is moderately high, while the visual binary fraction is low.…”

Section: Introductionmentioning

confidence: 99%

A spectroscopic survey on the multiplicity of high-mass stars

Chini

Hoffmeister

Nasseri

et al. 2012

Monthly Notices of the Royal Astronomical Society

335

367

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The formation of stars above about twenty solar masses and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (> 82%) with masses above 16 solar masses form close binary systems while this fraction rapidly drops to 20% for stars of 3 solar masses. The binary fractions of O- type stars among different environment classes are: clusters (72 \pm 13%), associations (73 \pm 8%), field (43 \pm 13%), and runaways (69 \pm 11%). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69% compared to 19-26% in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.Comment: 6 pages, 4 figures, accepted by MNRA

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High-resolution imaging of Galactic massive stars with AstraLux

Cited by 61 publications

References 33 publications

ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

ORBITAL AND PHYSICAL PROPERTIES OF THE σ Ori Aa, Ab, B TRIPLE SYSTEM

A COORDINATED X-RAY AND OPTICAL CAMPAIGN OF THE NEAREST MASSIVE ECLIPSING BINARY,δORIONIS Aa. IV. A MULTIWAVELENGTH, NON-LTE SPECTROSCOPIC ANALYSIS

A spectroscopic survey on the multiplicity of high-mass stars

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