{
  "abstract": "The recently discovered S301 star, with an orbital period of 8.7 years and eccentricity $e = 0.982$, reaches a pericenter of just $140\\,R_{\\mathrm{s}}$ --- approximately nine times closer than S2's $\\sim 1200R_{\\mathrm{s}}$ --- offering an unprecedented laboratory for testing strong-field gravity. We demonstrate that S301's stellar spin precession provides a novel probe of the PPN parameter $γ$, scaling as $(2γ_{\\mathrm{PPN}} + 1)/3$ relative to general relativity (GR). For maximum projected velocity shifts of $46.1~\\mathrm{km\\,s^{-1}}$, next-generation spectrographs could constrain $γ_{\\mathrm{PPN}}$ to $\\sim 10\\%$ precision. When combined with S301's orbital precession --- a substantial $\\sim 1.95^\\circ$ pericenter advance per orbit (GR prediction), approximately an order of magnitude larger than S2's $\\sim 0.2^\\circ$, constraining $(2β_{\\mathrm{PPN}} + 2γ_{\\mathrm{PPN}} - 1)/3$ --- the spin measurement breaks the $β$-$γ$ degeneracy. A MCMC analysis of projected S2 and S301 observations yields $σ_β\\approx 2.3 \\times 10^{-4}$, with the $γ$ precision limited by the spin precession measurement to $σ_γ\\approx 0.1$. While the spin precession provides an independent consistency check, its true significance lies in probing gravity at $ϕ/c^2 \\sim 10^{-4}$ and $v/c \\sim 0.08$ --- four orders of magnitude stronger than Solar System tests and an order of magnitude stronger than current S-star constraints. This complementary approach opens a new window for testing the PPN framework in the strong-field regime and demonstrates the power of combining multiple stellar probes at the Galactic Center.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.06977",
  "author_total": 2,
  "authors": [
    {
      "name": "Mohsen Khodadi"
    },
    {
      "name": "Salvatore Capozziello"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2cjyfmpmx8ftv.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.06977",
  "fulltext_url": null,
  "id": "2cjyfmpmx8ftv",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.06977",
  "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",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3103|Astrophysical Phenomena and Observations"
    ]
  ],
  "openalex": "W7212057505",
  "pdf_url": "https://arxiv.org/pdf/2609.06977",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2cjyfmpmx8ftv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.06977",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.06977"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301",
  "title_text": "A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/2cjyfmpmx8ftv",
  "venue": "arXiv",
  "versions": []
}