stars: early-type; binaries: spectroscopic; stars: magnetic fields; stars: abundances; stars: fundamental parameters; stars: individual: HD 164492C; stars: magnetic field
Abstract :
[en] HD 164492C is a spectroscopic triple stellar system that has been recently detected to possess a strong magnetic field. We have obtained high-resolution spectroscopic and spectropolarimetric observations over a time span of two years and derived physical, chemical and magnetic properties for this object. The system is formed by an eccentric close spectroscopic binary (Ca1-Ca2) with a period of 12.5 d, and a massive tertiary Cb. We calculated the orbital parameters of the close pair, reconstructed the spectra of the three components and determined atmospheric parameters and chemical abundances by spectral synthesis. From spectropolarimetric observations, multi-epoch measurements of the longitudinal magnetic fields were obtained. The magnetic field is strongly variable on time-scales of a few days, with a most probable period in the range of 1.4-1.6 d. Star Cb with T[SUB]eff[/SUB] ˜ 25 000 K is apparently the fastest rotator and the most massive star of this triple system and has anomalous chemical abundances with a marked overabundance of helium, 0.35±0.04 by number. We identified this star as being responsible for the observed magnetic field, although the presence of magnetic fields in the components of the Ca pair cannot be excluded. Star Ca1 with a temperature of about 24 000 K presents a normal chemical pattern, while the least massive star Ca2 is a mid-B-type star (T[SUB]eff[/SUB] ˜ 15 000 K) with an overabundance of silicon. The obtained stellar parameters of the system components suggest a distance of 1.5 kpc and an age of 10-15 Myr.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
González, J. F.; Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, Casilla de Correo 49, 5400 San Juan, Argentina
Hubrig, S.; Leibniz-Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany
Przybilla, N.; Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
Carroll, T.; Leibniz-Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany
Nieva, M.-F.; Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
Ilyin, I.; Leibniz-Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany
Järvinen, S.; Leibniz-Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany
Morel, Thierry ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Schöller, M.; European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
Castro, N.; Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109-1107, USA ; Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
Barbá, R.; Departamento de Física y Astronomía, Universidad de La Serena, Av. Cisternas 1200 Norte, La Serena, Chile
de Koter, A.; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, PO Box 94249, 1090 GE, Amsterdam, The Netherlands ; Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
Schneider, F. R. N.; Department of Physics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, United Kingdom
Kholtygin, A.; Chair of Astronomy, Astronomical Institute, St. Petersburg State University, Universitetski pr. 28, 198504, St. Petersburg, Russia
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