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A coordinated X-Ray and optical campaign of the nearest massive eclipsing binary, delta ORIONIS Aa. IV. A multiwavelength, non-lte spectroscopic analysis

  • 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 delta 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 delta Ori lies at about twice the Hipparcos distance, in the vicinity of the sigma-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 Delta V approximate to 2.(m)8. The inferred parameters suggest that the secondary is an early B-type dwarf (approximate to B1 V), while the tertiary is an early B-type subgiant (approximate to B0Eclipsing 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 delta 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 delta Ori lies at about twice the Hipparcos distance, in the vicinity of the sigma-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 Delta V approximate to 2.(m)8. The inferred parameters suggest that the secondary is an early B-type dwarf (approximate to B1 V), while the tertiary is an early B-type subgiant (approximate to B0 IV). We find evidence for rapid turbulent velocities (similar to 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 (logL(X)/L-Bol approximate to -6.85), initiating close to the stellar surface at R-0 similar to 1.1 R-*. Accounting for clumping, the mass-loss rate of the primary is found to be log (M) over dot approximate to -6.4 (M-circle dot yr(-1))., which agrees with hydrodynamic predictions, and provides a consistent picture along the X-ray, UV, optical, and radio spectral domains.show moreshow less

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Author:Tomer ShenarORCiDGND, Lida Oskinova, Wolf-Rainer HamannORCiDGND, Michael F. Corcoran, Anthony F. J. Moffat, Herbert Pablo, Noel D. Richardson, Wayne L. Waldron, David P. Huenemoerder, Jesus Maiz Apellaniz, Joy S. Nichols, Helge Todt, Yael Naze, Jennifer L. Hoffman, Andy M. T. Pollock, Ignacio Negueruela
DOI:https://doi.org/10.1088/0004-637X/809/2/135
ISSN:0004-637X (print)
ISSN:1538-4357 (online)
Parent Title (English):The astrophysical journal : an international review of spectroscopy and astronomical physics
Publisher:IOP Publ. Ltd.
Place of publication:Bristol
Document Type:Article
Language:English
Year of first Publication:2015
Year of Completion:2015
Release Date:2017/03/27
Tag:X-rays: stars; binaries: close; binaries: eclipsing; stars: early-type; stars: individual ([HD 36486]delta Ori A)
Volume:809
Issue:2
Pagenumber:20
Funder:Leibniz Graduate School for Quantitative Spectroscopy in Astrophysics; Leibniz Institute for Astrophysics Potsdam (AIP); institute of Physics and Astronomy of the University of Potsdam; DLR [50 OR 1302]; Chandra grants [GO3-14015A, GO3-14015E]; NSERC (Canada); FRQNT (Quebec); Spanish Government Ministerio de Economia y Competitividad (MINECO) [AYA2010-15 081, AYA2010-17 631]; Consejeria de Educacion of the Junta de Andaluc ia [P08-TIC-4075]; Centre du Recherche en Astrophysique du Quebec (CRAQ) fellowship; Fonds National de la Recherche Scientifique (Belgium); Communaute Francaise de Belgique; PRODEX XMM and Integral contracts; "Action de Recherche Concertee" (CFWB-Academie Wallonie Europe); NASA [NNX13AF40G]; NSF [AST-0807477]; Spanish Mineco [AYA2012-39364-C02-01/02]; European Union
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert