{
  "abstract": "Context. MWC 656 is a Be/X-ray binary identified as an emission-line object, X-ray and radio source and might be a weak gamma-ray source, harbouring an enigmatic secondary component. Aims. Our aim here is to study the orbital modulation of the H-alpha emission line, disc truncation and to evaluate the binary parameters. Methods. During the period 2021-2026, we obtained high resolution (30000) optical spectra of MWC 656 and analysed them together with the published data. Results. We find an orbital modulation of the H_alpha emission line with period P orb = 60.43 +/- 0.03 d. By assuming that the Be circumstellar disc is truncated by the companion, we estimate orbital eccentricity e = 0.11 +/- 0.01, semimajor axis a=160 R_sun, and mass of the binary M_1 + M_2 = 15.1 M_sun. Conclusions. The orbital modulation of the H_alpha emission suggests that (1) in this object we have a new type of cyclic variability of a Be disc; (2) the orbit is mildly eccentric; and (3) the secondary component of MWC 656 is a massive object 5 M_sun, more massive than the neutron stars - a stellar-mass black hole or a massive stripped star.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.27500",
  "author_total": 11,
  "authors": [
    {
      "name": "R. Zamanov"
    },
    {
      "name": "V. Marchev"
    },
    {
      "name": "K. A. Stoyanov"
    },
    {
      "name": "M. D. Christova"
    },
    {
      "name": "M. Minev"
    },
    {
      "name": "M. Moyseev"
    },
    {
      "name": "D. Marchev"
    },
    {
      "name": "J. Marti"
    },
    {
      "name": "M. F. Bode"
    },
    {
      "name": "P. Markishki"
    },
    {
      "name": "S. Stefanov"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3c9ac2np83emw.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.27500",
  "fulltext_url": null,
  "id": "3c9ac2np83emw",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.27500",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7214153388",
  "pdf_url": "https://arxiv.org/pdf/2609.27500",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3c9ac2np83emw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.27500",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.27500"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "H_alpha observations of the Be/X-ray binary MWC 656",
  "title_text": "H_alpha observations of the Be/X-ray binary MWC 656",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/3c9ac2np83emw",
  "venue": "arXiv",
  "versions": []
}