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Orbital and physical properties of the sigma Ori Aa, Ab, B triple system



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Simón Díaz, S. and Caballero, J. A. and Lorenzo, J. and Maíz Apellániz, J. and Schneider, F. R. N. and Negueruela, I. and Barbá, R. H. and Dorda, R. and Marco, A. and Montes Gutiérrez, David and Pellerin, A. and Sánchez Bermúdez, J. and Sódor, A. and Sota, A. (2015) Orbital and physical properties of the sigma Ori Aa, Ab, B triple system. Astrophysical journal, 799 (2). ISSN 0004-637X


Official URL: http://dx.doi.org/10.1088/0004-637X/799/2/169



We provide a complete characterization of the astrophysical properties of the sigma Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric sigma 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-Filhes method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the sigma 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 sigma Ori Aa, Ab pair. We provided indirect arguments indicating that sigma 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 sigma 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 sigma 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 s Orionis cluster, the interpretation of the strong X-ray emission detected for sigma Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects.

Item Type:Article
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© 2015. The American Astronomical Society. All rights reserved. This research made use of SIMBAD, operated at Centre de Données astronomiques de Strasbourg, France, and NASA's Astrophysics Data System. Financial support was provided by the Spanish Ministerio de Ciencia e Innovación and Ministerio de Economía y Competitividad under grants AYA2010-17631, AYA2010-15081, AYA2010-21697-C05-04, AYA2011-30147-C03-03, AYA2012-39364-C02-01/02, and Severo Ochoa SEV-2011-0187, and by the Canary Islands Government under grant PID2010119. R.H.B. acknowledges support from FONDECYT Regular project 1140076. J.S.-B. acknowledges support by the JAE-PreDoc program of the Spanish Consejo Superior de Investigaciones Científicas (CSIC). A.S. acknowledges support by the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences. We acknowledge F. Najarro, J. Puls, A. Herrero, J. Casares, and H. Blau for interesting discussions during the development of this paper and their useful comments on one of the latest drafts before submission. We thank G. Schaefer for providing us some information about the results from the analysis of the interferometric observations prior to publication. Lastly, we thank the anonymous referee for a very professional report that helped us to improve the first version of the manuscript. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Based on observations obtained with the HERMES spectrograph, which is supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of K.U. Leuven, Belgium, the Fonds National de la Recherche Scientifique (F.R.S.-FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genève, Switzerland, and the Thringer Landessternwarte Tautenburg, Germany. The Hobby-Eberly Telescope (HET) is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Uncontrolled Keywords:Main-sequence stars; Fed echelle spectrograph; Nearby ob associations; X-ray variability; Low-mass stars; Orionis cluster; Horsehead nebula; Galactic O; Differential photometry; Rown dwarfs
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:29207
Deposited On:16 Mar 2015 10:27
Last Modified:10 Dec 2018 15:05

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