{
  "id": "2108.07814",
  "version": "v1",
  "published": "2021-08-17T18:00:01.000Z",
  "updated": "2021-08-17T18:00:01.000Z",
  "title": "The observed multiplicity properties of B-type stars in the Galactic young open cluster NGC 6231",
  "authors": [
    "G. Banyard",
    "H. Sana",
    "L. Mahy",
    "J. Bodensteiner",
    "J. I. Villaseñor",
    "C. J. Evans"
  ],
  "categories": [
    "astro-ph.SR",
    "astro-ph.GA"
  ],
  "abstract": "It is well known that massive O-stars are frequently (if not always) found in binary or higher-order multiple systems, but this fact has been less robustly investigated for the lower mass range of the massive stars, represented by the B-type stars. Obtaining the binary fraction and orbital parameter distributions of B-type stars is crucial to understand the impact of multiplicity on the archetypal progenitor of core-collapse supernovae as well as to properly investigate formation channels for gravitational wave progenitors. This work aims to characterise the multiplicity of the B-star population of the young open cluster NGC 6231 through multi-epoch optical spectroscopy of 80 B-type stars. We analyse 31 FLAMES/GIRAFFE observations of 80 B-type stars, monitoring their radial velocities (RVs) and performing a least-squares spectral analysis (Lomb-Scargle) to search for periodicity in those stars with statistically significant variability in their RVs. We constrain an observed spectroscopic binary fraction of $33\\pm5$% for the B-type stars of NGC 6231, with a first order bias-correction giving a true spectroscopic binary fraction of $52\\pm8$%. Out of 27 B-type binary candidates, we obtained orbital solutions for 20 systems: 15 single-lined (SB1) and 5 double-lined spectroscopic binaries (SB2s). We present these orbital solutions and the orbital parameter distributions associated with them. Our results indicate that Galactic B-type stars are less frequently found in binary systems than their more massive O-type counterparts, but their orbital properties generally resemble those of B- and O-type stars in both the Galaxy and Large Magellanic Cloud.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-08-17T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "b-type stars",
      "galactic young open cluster ngc",
      "multiplicity properties",
      "orbital parameter distributions",
      "spectroscopic binary fraction"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}