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Karl, Martina; Pfuhl, Oliver; Eisenhauer, Frank; Genzel, Reinhard; Grellmann, Rebekka; Habibi, Maryam; Abuter, Roberto; Accardo, Matteo; Amorim, António; Anugu, Narsireddy; Ávila, Gerardo; Benisty, Myriam; Berger, Jean-Philippe; Blind, Nicolas; Bonnet, Henri; Bourget, Pierre; Brandner, Wolfgang; Brast, Roland; Buron, Alexander; o Garatti, Alessio Caratti; Chapron, Frédéric; Clénet, Yann; Collin, Claude; du Foresto, Vincent Coudé; [...]

Multiple star systems in the Orion nebula

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  • Media type: E-Article
  • Title: Multiple star systems in the Orion nebula
  • Contributor: Karl, Martina; Pfuhl, Oliver; Eisenhauer, Frank; Genzel, Reinhard; Grellmann, Rebekka; Habibi, Maryam; Abuter, Roberto; Accardo, Matteo; Amorim, António; Anugu, Narsireddy; Ávila, Gerardo; Benisty, Myriam; Berger, Jean-Philippe; Blind, Nicolas; Bonnet, Henri; Bourget, Pierre; Brandner, Wolfgang; Brast, Roland; Buron, Alexander; o Garatti, Alessio Caratti; Chapron, Frédéric; Clénet, Yann; Collin, Claude; du Foresto, Vincent Coudé; [...]
  • imprint: EDP Sciences, 2018
  • Published in: Astronomy & Astrophysics
  • Language: Not determined
  • DOI: 10.1051/0004-6361/201833575
  • ISSN: 0004-6361; 1432-0746
  • Keywords: Space and Planetary Science ; Astronomy and Astrophysics
  • Origination:
  • Footnote:
  • Description: <jats:p>This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori B, <jats:italic>θ</jats:italic><jats:sup>2</jats:sup> Ori B, and <jats:italic>θ</jats:italic><jats:sup>2</jats:sup> Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori A, <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori C, <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori D, and <jats:italic>θ</jats:italic><jats:sup>2</jats:sup> Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori C and we are able to derive a new orbit for <jats:italic>θ</jats:italic><jats:sup>1</jats:sup> Ori D. We find a system mass of 21.7 <jats:italic>M</jats:italic><jats:sub>⊙</jats:sub> and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.</jats:p>
  • Access State: Open Access