{
  "abstract": "We present multiepoch high-resolution optical spectroscopy ( R ≃ 80,000) of the emission-line object NaSt1 to test its proposed binary nature, along with long-term multiband photometry, mid-infrared spectroscopy, and spatially resolved integral field unit (IFU) spectroscopy to probe the circumstellar kinematics of the system. We detect two groups of 36 emission lines showing radial velocity (RV) variation with a mean period of 311 ± 5 days, but varying in opposite phase. We associate these two groups with the optically thick wind of the stripped primary star and the wind–wind collision region with the companion star, providing strong evidence for binarity. The RV and light curve (LC) periods are consistent within the uncertainties, ruling out ellipsoidal modulation, which would require an orbital period of about 620 days. The RV–LC phase relationship and high-ionization lines favor binary interaction over pulsations. We model the 1–5 μ m spectrum of NaSt1 and find two optically thin dust components: hot: T h ≃ 1230 K and M h ≃ 2 × 10 ⁻¹⁰ M ⊙ , and warm: T c ≃ 660 K and M c ≃ 3 × 10 ⁻⁸ M ⊙ . IFU spectroscopy spatially resolves the circumstellar medium in the [N ii ] λ 6548 and λ 6584 emission lines, showing a deprojected expansion velocity of ∼31 km s ⁻¹ , implying a dynamical age of ∼40 yr. This short timescale suggests that the nebula was produced by recent mass loss. The system may represent a Galactic analog of a massive binary undergoing a mass-loss process to become a stripped-envelope supernova progenitor.",
  "abstract_shown": true,
  "affiliations": [
    "Suranaree University of Technology",
    "National Astronomical Research Institute of Thailand",
    "California Institute of Technology",
    "University of California",
    "Carnegie Institution for Science",
    "Columbia University",
    "Flatiron Institute",
    "Michigan State University",
    "University of California at Santa Cruz",
    "University of Arizona",
    "The Thacher School"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 14,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Kittipong Wangnok",
      "orcid": "0000-0002-7593-2748"
    },
    {
      "affs": [
        1
      ],
      "name": "Samaporn Tinyanont",
      "orcid": "0000-0002-1481-4676"
    },
    {
      "affs": [
        2
      ],
      "name": "Ryan M. Lau",
      "orcid": "0000-0003-0778-0321"
    },
    {
      "affs": [
        3
      ],
      "name": "Ryan J. Foley",
      "orcid": "0000-0002-2445-5275"
    },
    {
      "affs": [
        4
      ],
      "name": "R. Paul Butler",
      "orcid": "0000-0003-1305-3761"
    },
    {
      "affs": [
        0
      ],
      "name": "Poemwai Chainakun",
      "orcid": "0000-0002-9099-4613"
    },
    {
      "affs": [
        3
      ],
      "name": "Kyle W. Davis",
      "orcid": "0000-0002-5680-4660"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Kishalay De",
      "orcid": "0000-0002-8989-0542"
    },
    {
      "affs": [
        6,
        7
      ],
      "name": "Jared A. Goldberg",
      "orcid": "0000-0003-1012-3031"
    },
    {
      "affs": [
        8
      ],
      "name": "Bradford Holden",
      "orcid": "0000-0002-6153-3076"
    },
    {
      "affs": [
        4
      ],
      "name": "Adriana Kuehnel"
    },
    {
      "affs": [
        9
      ],
      "name": "Nathan Smith",
      "orcid": "0000-0001-5510-2424"
    },
    {
      "affs": [
        10
      ],
      "name": "Jonathan J. Swift",
      "orcid": "0000-0002-9486-818X"
    },
    {
      "affs": [
        8
      ],
      "name": "Steven S. Vogt",
      "orcid": "0000-0001-7177-7456"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7f996ev0cgtp8.bib",
  "cited_by": 0,
  "doi": "10.3847/1538-4357/aea4a0",
  "fulltext_url": null,
  "id": "7f996ev0cgtp8",
  "issns": [
    "0004-637X",
    "1538-4357"
  ],
  "landing_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea4a0",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7154612395",
  "pdf_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea4a0/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-07",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/7f996ev0cgtp8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:11Z",
      "native_id": "10.3847/1538-4357/aea4a0",
      "source": "crossref",
      "url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea4a0"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "title": "Radial Velocity Evidence for a Post-mass-transfer Massive Binary System NaSt1",
  "title_text": "Radial Velocity Evidence for a Post-mass-transfer Massive Binary System NaSt1",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:11Z",
  "url": "https://research.draconitic.com/paper/7f996ev0cgtp8",
  "venue": "The Astrophysical Journal",
  "versions": []
}