{
  "abstract": "Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be $M_{\\rm WD}$=0.60$\\pm$0.10 $M_{\\odot}$. I found an orbital period of $P$=0.1884 days, and have tracked 20 times of photometric minima from 2013--2025. I measure that $P$ increased from before to after the eruption with $P_{\\rm pre}$=0.1883919$\\pm$0.0000018 days and $P_{\\rm post}$=0.1884043$\\pm$0.0000018 days, for $ΔP$/$P$=66$_{-18}^{+21}$ parts-per-million. With correction for the angular momentum loss by the binary during the eruption, I derive that the nova ejected $M_{\\rm ejecta}$=7.5$\\times$10$^{-4}$ $M_{\\odot}$, with an extreme range of (2.9--40)$\\times$10$^{-4}$ $M_{\\odot}$. The mass accreted during the previous eruption cycle comes from the trigger mass, and is $M_{\\rm accreted}$=(1.6$\\pm$0.4)$\\times$10$^{-4}$ $M_{\\odot}$. V1405 Cas provides counterexamples against five claims about CV evolution that have dominated since the 1980s. First, V1405 Cas has positive $\\dot{P}$, and this is contrary to the Magnetic Braking Model. Second, the $ΔP$ is 20$\\times$ too small to allow the system to fade into a hibernation state. Third, $M_{\\rm WD}$ is decreasing over time, as shown by $M_{\\rm ejecta}$$>$$M_{\\rm accreted}$ and by being a neon nova. Fourth, V1405 Cas is not a Type Ia supernova progenitor, for the same reasons. Fifth, the orbital period of V1405 Cas increased by $+$75 ppm from 2013--2025, as a counterexample to the pervasive idea that cataclysmic variables are universally declining in period from evolution. V1405 Cas is the latest of recent measures of $ΔP$ and $\\dot{P}$ for 52 cataclysmic variables and 25 X-ray binaries that have together refuted all five claims.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.10990",
  "author_total": 1,
  "authors": [
    {
      "name": "Bradley E. Schaefer"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8bn38j537c5tw.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.10990",
  "fulltext_url": null,
  "id": "8bn38j537c5tw",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.10990",
  "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.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7212239265",
  "pdf_url": "https://arxiv.org/pdf/2609.10990",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-10",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8bn38j537c5tw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:26Z",
      "native_id": "2609.10990",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.10990"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "Classical Nova V1405 Cas Had $M_{\\rm ejecta}$$>$$M_{\\rm accreted}$ and so is Unlikely to be a Type Ia Supernova Progenitor",
  "title_text": "Classical Nova V1405 Cas Had M_ejecta>M_accreted and so is Unlikely to be a Type Ia Supernova Progenitor",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:26Z",
  "url": "https://research.draconitic.com/paper/8bn38j537c5tw",
  "venue": "arXiv",
  "versions": []
}