{
  "abstract": "Compact double neutron star (DNS) systems are unique laboratories for testing gravitational theories and studying DNS mergers. Here we report the properties of a new DNS system, PSR J1856--0039, discovered in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulsar is mildly recycled with a period of 23.4~ms in a compact eccentric orbit ($e=0.106$) with an orbital period of 2.36 hours. By following up FAST observations, we measured the relativistic effects, including the orbital period derivative $\\dot{P}_{\\rm orb}=-1.284\\pm0.019\\times10^{-12}$ s s$^{-1}$, periastron advance $\\dotω=17.5859\\pm0.0007$ deg yr$^{-1}$, and Einstein delay $γ=0.445\\pm0.011$ ms. This DNS system has a low orbital inclination of $i=133^\\circ.2\\pm1^\\circ.1$ and the lowest total mass of any known DNS, $M_{\\rm tot}=2.48841\\pm0.00015 M\\odot$, with a determined pulsar mass of $1.304\\pm0.022 M_\\odot$ and a companion mass of $1.185\\pm0.022 M_\\odot$, one of the lowest neutron-star masses. The observed orbital decay due to gravitational-wave emission $\\dot{P}^{\\rm GW}_{\\rm orb,obs}$ and the orbital decay predicted by general relativity $\\dot{P}^{\\rm GW}_{\\rm orb,pred}$ are consistent at a level of $\\dot{P}^{\\rm GW}_{\\rm orb,obs}/\\dot{P}^{\\rm GW}_{\\rm orb,pred}=$1.009(14) (68% confidence). This DNS will merge after 82 Myr and may form a stable neutron star or collapse into a black hole after spin-down. Long-term monitoring could potentially probe the Lense-Thirring precession.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Yang et al., Phys. Rev. Lett., 2026, 137, 121401",
  "arxiv": "2607.27333",
  "author_total": 14,
  "authors": [
    {
      "name": "Z. L. Yang"
    },
    {
      "name": "J. L. Han"
    },
    {
      "name": "W. Q. Su"
    },
    {
      "name": "P. F. Wang"
    },
    {
      "name": "C. Wang"
    },
    {
      "name": "T. Wang"
    },
    {
      "name": "D. J. Zhou"
    },
    {
      "name": "Yi Yan"
    },
    {
      "name": "J. Xu"
    },
    {
      "name": "W. C. Jing"
    },
    {
      "name": "N. N. Cai"
    },
    {
      "name": "R. X. Xu"
    },
    {
      "name": "H. G. Wang"
    },
    {
      "name": "X. P. You"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/at6xa1v8444m5.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2607.27333",
  "fulltext_url": null,
  "id": "at6xa1v8444m5",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2607.27333",
  "language": null,
  "licence": "CC-BY-NC-SA-4.0",
  "licence_label": "CC BY-NC-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.HE"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2607.27333",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-16",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/at6xa1v8444m5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "2607.27333",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2607.27333"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Relativistic effects of PSR~J1856--0039 double neutron star system in a 2.36-hour compact orbit",
  "title_text": "Relativistic effects of PSR~J1856--0039 double neutron star system in a 2.36-hour compact orbit",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/at6xa1v8444m5",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1103/hmjp-htd1",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}