{
  "abstract": "We report the discovery of periodic radio bursts from the T8 brown dwarf WISE J151721.13+052929.3 (WISE J1517+05), detected with ASKAP and MeerKAT. The emission is characterised by a stable periodicity of $1.149 \\pm 0.002$ hr, placing WISE J1517+05 among the fastest rotating radio-detected ultracool dwarfs (UCDs). The radio bursts are broadband and highly variable, reaching a peak spectral luminosity of $L_ν = 5.6 \\times 10^{15}\\,\\mathrm{erg\\,s^{-1}\\,Hz^{-1}}$, making WISE J1517+05 the brightest periodic UCD to date. The high brightness temperature of the radio bursts ($T_B>10^{11}$ K), combined with the rotational modulation, strongly favour an auroral electron cyclotron maser emission (ECME) origin. In contrast to most known radio-bursting UCDs, the bursts exhibit relatively low and variable circular polarisation fractions (typically $\\sim 20\\%$). These properties suggest significant depolarisation of intrinsically highly polarised ECME, likely due to propagation effects in a structured magnetospheric plasma. Notably, we also observe a polarisation reversal within a single burst profile, which is currently unexplained. We model the emission using a dipolar magnetic field with emission arising from a single active field line, and find a moderate inclination angle of $i = 47.9^{+11.4}_{-9.2}$ degrees and a magnetic obliquity of $β= 40.1^{+9.2}_{-10.9}$ degrees. WISE J1517+05 expands the parameter space of radio-active UCDs toward higher luminosities and lower polarisation fractions, suggesting that current surveys may be sensitive to a larger population than previously recognised, while searches relying on methods that assume high circular polarisation fractions risk missing a subset of UCDs. More broadly, this discovery reinforces the idea that rapid rotation plays a key role in generating strong dipolar magnetic fields in UCDs that can give rise to auroral radio emission.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.36336",
  "author_total": 7,
  "authors": [
    {
      "name": "Iris de Ruiter"
    },
    {
      "name": "Joshua Pritchard"
    },
    {
      "name": "Tara Murphy"
    },
    {
      "name": "Andrew K. Hughes"
    },
    {
      "name": "David L. Kaplan"
    },
    {
      "name": "Kovi Rose"
    },
    {
      "name": "Andrew Zic"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cta9hv0c9q2r9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.36336",
  "fulltext_url": null,
  "id": "cta9hv0c9q2r9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.36336",
  "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.EP"
    ],
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7224093322",
  "pdf_url": "https://arxiv.org/pdf/2610.36336",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-26",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cta9hv0c9q2r9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:50Z",
      "native_id": "2610.36336",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.36336"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Periodic radio emission from a rapidly rotating T8 ultracool dwarf",
  "title_text": "Periodic radio emission from a rapidly rotating T8 ultracool dwarf",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:50Z",
  "url": "https://research.draconitic.com/paper/cta9hv0c9q2r9",
  "venue": "arXiv",
  "versions": []
}