Classical Nova V1405 Cas Had M ejecta > M accreted and So Is Unlikely to Be a Type Ia Supernova Progenitor
- 1Louisiana State University
Abstract
Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be M WD = 0.60 ± 0.10 M ⊙ . I found an orbital period of P = 0.1884 day and have tracked 20 times of photometric minima from 2013–2025. I measure that P increased from before to after the eruption with P pre = 0.1883919 ± 0.0000018 day and P post = 0.1884043 ± 0.0000018 day, for Δ P / P = 66 − 18 + 21 ppm. With correction for the angular momentum loss by the binary during the eruption, I derive that the nova ejected M ejecta = 7.5 × 10 ⁻⁴ M ⊙ , with an extreme range of (2.9–40) × 10 ⁻⁴ M ⊙ . The mass accreted during the previous eruption cycle comes from the trigger mass and is M accreted = (1.6 ± 0.4) × 10 ⁻⁴ M ⊙ . V1405 Cas provides counterexamples against five claims about cataclysmic variable (CV) evolution that have dominated since the 1980s. First, V1405 Cas has positive P ̇ , and this is contrary to the magnetic braking model. Second, the Δ P is 20× too small to allow the system to fade into a hibernation state. Third, M WD is decreasing over time, as shown by M ejecta > M 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 CVs are universally declining in period from evolution. V1405 Cas is the latest of recent measures of Δ P and P ̇ for 52 CVs and 25 X-ray binaries that have together refuted all five claims.
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BibTeX
@article{schaefer2026classical,
title = {{Classical Nova V1405 Cas Had M ejecta > M accreted and So Is Unlikely to Be a Type Ia Supernova Progenitor}},
author = {Bradley E. Schaefer},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea146},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea146},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Classical Nova V1405 Cas Had M ejecta > M accreted and So Is Unlikely to Be a Type Ia Supernova Progenitor
AU - Bradley E. Schaefer
PY - 2026
DA - 2026/10/22
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea146
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea146
AB - Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be M WD = 0.60 ± 0.10 M ⊙ . I found an orbital period of P = 0.1884 day and have tracked 20 times of photometric minima from 2013–2025. I measure that P increased from before to after the eruption with P pre = 0.1883919 ± 0.0000018 day and P post = 0.1884043 ± 0.0000018 day, for Δ P / P = 66 − 18 + 21 ppm. With correction for the angular momentum loss by the binary during the eruption, I derive that the nova ejected M ejecta = 7.5 × 10 ⁻⁴ M ⊙ , with an extreme range of (2.9–40) × 10 ⁻⁴ M ⊙ . The mass accreted during the previous eruption cycle comes from the trigger mass and is M accreted = (1.6 ± 0.4) × 10 ⁻⁴ M ⊙ . V1405 Cas provides counterexamples against five claims about cataclysmic variable (CV) evolution that have dominated since the 1980s. First, V1405 Cas has positive P ̇ , and this is contrary to the magnetic braking model. Second, the Δ P is 20× too small to allow the system to fade into a hibernation state. Third, M WD is decreasing over time, as shown by M ejecta > M 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 CVs are universally declining in period from evolution. V1405 Cas is the latest of recent measures of Δ P and P ̇ for 52 CVs and 25 X-ray binaries that have together refuted all five claims.
SN - 0004-637X
SN - 1538-4357
ER -