{
  "abstract": "We present a multi-wavelength analysis of the highly bipolar object Hen 2-57 based on new optical spectroscopy from the Southern African Large Telescope (SALT), complemented by archival imaging, and long-term time-series photometry from OGLE and NEOWISE. The nebula exhibits a pronounced hourglass morphology with a symmetry axis at a position angle of $110\\pm5^{\\circ}$ and an average lobe opening angle of $\\sim$$53^{\\circ}$. We also identify pronounced north--south brightness asymmetry, with the southern parts of lobes consistently brighter. The spectral energy distribution shows a strong mid-infrared excess that cannot be reproduced by a single-temperature blackbody, indicating the presence of a dense circumstellar dust structure, likely in the form of a disk or torus, analogous to that observed in M 2-9. Optical spectroscopy reveals a complex kinematic structure in which the central core is redshifted relative to both the eastern ($55\\pm4\\ \\mathrm{km\\,s^{-1}}$) and western ($46\\pm3\\ \\mathrm{km\\,s^{-1}}$) lobes. While standard diagnostic diagrams place the extended lobes in the planetary nebula regime, emission-line diagnostics of the central core are consistent with those of symbiotic stars. The same region also exhibits a steep Balmer decrement, indicative of significant internal dust extinction. Long-term OGLE photometry shows no evidence for coherent stellar pulsations, whereas NEOWISE photometry reveals a gradual mid-infrared fading of $\\sim$0.25 mag between 2010 and 2024. Together, these properties support a scenario in which Hen 2-57 hosts a dust-enshrouded D-type symbiotic central engine actively shaping the surrounding bipolar nebula, making it a close analogue of M 2-9.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.19874",
  "author_total": 4,
  "authors": [
    {
      "name": "J. Merc"
    },
    {
      "name": "J. Mikołajewska"
    },
    {
      "name": "K. Iłkiewicz"
    },
    {
      "name": "A. Udalski"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2h7d0ma1kke01.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19874",
  "fulltext_url": null,
  "id": "2h7d0ma1kke01",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19874",
  "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.SR"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.19874",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2h7d0ma1kke01.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.19874",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19874"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Highly bipolar planetary nebula Hen 2-57 and its possible symbiotic core",
  "title_text": "Highly bipolar planetary nebula Hen 2-57 and its possible symbiotic core",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/2h7d0ma1kke01",
  "venue": "arXiv",
  "versions": []
}