{
  "abstract": "Stellar magnetic activity alters thousands of spectral lines, limiting high-precision radial-velocity measurements, abundance analyses, and planetary characterization. We present a preliminary classification of 6403 atomic lines in synthetic visible spectra from a sequence of NLTE semi-empirical dG2 atmospheric models with increasing chromospheric heating. Principal-component analysis shows that the dominant component traces overall response amplitude, while the second distinguishes early from late responders. DBSCAN applied in the full nine-dimensional response space identifies a dense stable core and an activity- sensitive non-core group comprising about 11% of the lines. The stable core provides candidate lines for activity-insensitive measurements, while sensitive lines provide candidate activity diagnostics. Sensitive transitions tend to have low lower-level energies, although the populations overlap, making lower-level energy a statistical discriminator rather than a line-by-line predictor. A spectral sensitivity map shows that small average variations can hide nonlinear or compensating responses, demonstrating the value of the complete line-response trajectory for classification.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.22532",
  "author_total": 2,
  "authors": [
    {
      "name": "Juan I. Peralta"
    },
    {
      "name": "Mariela C. Vieytes"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3079h5stbfg6c.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.22532",
  "fulltext_url": null,
  "id": "3079h5stbfg6c",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.22532",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7214002335",
  "pdf_url": "https://arxiv.org/pdf/2609.22532",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3079h5stbfg6c.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.22532",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.22532"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Chromospheric sensitivity of stellar spectral lines: an unsupervised machine learning classification",
  "title_text": "Chromospheric sensitivity of stellar spectral lines: an unsupervised machine learning classification",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/3079h5stbfg6c",
  "venue": "arXiv",
  "versions": []
}