{
  "abstract": "Context: With Gaia's third Data Release (DR3), low-resolution BP/RP (XP) spectra became available for more than 219 million sources. In previous work, we developed a fast method for detecting absorption and emission lines while measuring their equivalent widths directly from the XP spectral coefficients. Aims: We conduct a systematic search for H$α$ emitters in the Gaia DR3 XP spectra. Methods: We measured the equivalent width of the Balmer H$α$ line for all sources with Gaia XP spectra and selected an initial sample of 556100 sources depicting an H$α$ emission-like feature at $2σ$ level or above. Using a semi-supervised classifier complemented by manual spectral labelling, we removed sources that merely masqueraded as emission-line stars. Results: We find that 95% of the initial candidates are most likely cool M-type stars, where a molecular absorption band gives rise to a local maximum that can mimic H$α$ emission. Subsequently, 28394 sources were flagged as bona fide H$α$ emitters using the Gaia DR3 XP spectra. The majority are Be-like candidates (26287), M-type emission-line stars (717), Herbig Ae/Be candidates (525), quasi-stellar objects (204), Wolf-Rayet stars (177), cataclysmic variables (51), and carbon stars (18), among other sources. Our equivalent widths and stellar classifications agree well with results from higher-resolution studies and recent Gaia XP spectra-based catalogues. Ground-based spectroscopic follow-up for some of the newly found H$α$ emitters reinforces our confidence in the catalogue.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: A&A, 714, A90 (2026)",
  "arxiv": "2606.21420",
  "author_total": 11,
  "authors": [
    {
      "name": "S. Malhotra"
    },
    {
      "name": "M. Weiler"
    },
    {
      "name": "F. Anders"
    },
    {
      "name": "J. M. Carrasco"
    },
    {
      "name": "G. Garcia-Moreno"
    },
    {
      "name": "C. Jordi"
    },
    {
      "name": "N. Blagorodnova"
    },
    {
      "name": "A. Castro-Ginard"
    },
    {
      "name": "J. Castañeda"
    },
    {
      "name": "F. Boix"
    },
    {
      "name": "X. Luri"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bakbzbp7sph5j.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.21420",
  "fulltext_url": null,
  "id": "bakbzbp7sph5j",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.21420",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2606.21420",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bakbzbp7sph5j.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2606.21420",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.21420"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "XP-TEAL: Gaia XP Tool for Emission and Absorption Lines II. Gaia-HELIX catalogue of H$α$ emitters in Gaia BP/RP spectra",
  "title_text": "XP-TEAL: Gaia XP Tool for Emission and Absorption Lines II. Gaia-HELIX catalogue of Hα emitters in Gaia BP/RP spectra",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/bakbzbp7sph5j",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1051/0004-6361/202661499",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}