{
  "abstract": "Contact binaries (CBs) are key systems for investigating the late evolutionary stages that may lead to stellar coalescence. Systems with an extremely low mass ratio and high fill-out factor are of particular interest as potential merger candidates and possible progenitors of luminous red novae. A combined photometric and spectroscopic study of the CB systems AL Lep, ASAS J082243+1927.0, and ZZ PsA is presented. The aim is to derive self-consistent orbital and physical parameters, assess their evolutionary state, and examine whether they have reached the terminal and unstable phase of their evolution. High-resolution VLT/UVES spectra were analysed to derive radial velocity values, spectroscopic mass ratio, and metallicity. The results were combined with multi-band light-curve modelling within a Monte Carlo framework to determine the system geometries and absolute parameters. Orbital period variations were investigated through O-C analysis, while the evolutionary status of the systems was assessed using the Darwin instability criterion, critical mass ratio estimates, fill-out factor, and orbital period variation. Mass ratio values of q = 0.1332, 0.1041, and 0.0789 were derived for AL Lep, ASAS J082243+1927.0, and ZZ PsA, respectively. The corresponding primary mass values are M1 = 1.656 +/- 0.081 Msun, 1.275 +/- 0.078 Msun, and 1.795 +/- 0.111 Msun. The locations of their components show significant deviations from single-star ZAMS and TAMS reference curves, indicating strong binary interaction and energy redistribution through the common envelope. The spin-to-orbital angular momentum ratio for AL Lep and ASAS J082243+1927.0 remains below the standard Darwin instability threshold, while ZZ PsA lies close to the instability regime and may be consistent with an unstable configuration within the derived uncertainties.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Astronomy & Astrophysics, 713, A271 (2026)",
  "arxiv": "2608.28051",
  "author_total": 6,
  "authors": [
    {
      "name": "Sofia Palafouta"
    },
    {
      "name": "Kosmas D. Gazeas"
    },
    {
      "name": "Pasi Hakala"
    },
    {
      "name": "Stanislaw Zola"
    },
    {
      "name": "Athanasios Kafkas"
    },
    {
      "name": "Maria Garro"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bccznmj4v8hd1.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.28051",
  "fulltext_url": null,
  "id": "bccznmj4v8hd1",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.28051",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.SR"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2608.28051",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bccznmj4v8hd1.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:12Z",
      "native_id": "2608.28051",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.28051"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "CoBiToM project. III. Physical characterisation of the potential merger candidates AL Lep, ASAS J082243+1927.0, and ZZ PsA",
  "title_text": "CoBiToM project. III. Physical characterisation of the potential merger candidates AL Lep, ASAS J082243+1927.0, and ZZ PsA",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:12Z",
  "url": "https://research.draconitic.com/paper/bccznmj4v8hd1",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1051/0004-6361/202661420",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}