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Title: The HD 5980 multiple system: Masses and evolutionary status

New spectroscopic observations of the LBV/WR multiple system HD 5980 in the Small Magellanic Cloud are used to address the question of the masses and evolutionary status of the two very luminous stars in the 19.3 day eclipsing binary system. Two distinct components of the N V 4944 Å line are detected in emission and their radial velocity variations are used to derive masses of 61 and 66 M {sub ☉}, under the assumption that binary interaction effects on this atomic transition are negligible. We propose that this binary system is the product of quasi-chemically homogeneous evolution with little or no mass transfer. Thus, both of these binary stars may be candidates for gamma-ray burst progenitors or even pair instability supernovae. Analysis of the photospheric absorption lines belonging to the third-light object in the system confirm that it consists of an O-type star in a 96.56 day eccentric orbit (e = 0.82) around an unseen companion. The 5:1 period ratio and high eccentricities of the two binaries suggest that they may constitute a hierarchical quadruple system.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ; ;  [5] ;  [6]
  1. Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Ave. Universidad S/N, Cuernavaca, Morelos 62210 (Mexico)
  2. Las Campanas Observatory, The Carnegie Observatories, Colina El Pino s/n, Casillas 601, La Serena (Chile)
  3. Department of Physics and Astronomy, and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), 3941 O'Hara Street, University of Pittsburgh, Pittsburgh, PA 15260 (United States)
  4. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, and Instituto de Astrofísica de La Plata (CCT La Plata-CONICET), Paseo del Bosque S/N, B1900FWA La Plata (Argentina)
  5. Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn (Germany)
  6. Departamento de Física, Av. Juan Cisternas 1200 Norte, Universidad de la Serena, La Serena (Chile)
Publication Date:
OSTI Identifier:
22342249
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 148; Journal Issue: 4; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; COSMIC GAMMA BURSTS; ECLIPSE; EMISSION; INSTABILITY; INTERACTIONS; MAGELLANIC CLOUDS; MASS TRANSFER; ORBITS; RADIAL VELOCITY; STAR EVOLUTION; SUPERNOVAE; VISIBLE RADIATION