Classical Nova V1405 Cas Had Mejecta>Maccreted and so is Unlikely to be a Type Ia Supernova Progenitor
Abstract
Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be MWD=0.60±0.10 M⊙. 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 Ppre=0.1883919±0.0000018 days and Ppost=0.1884043±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 Mejecta=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 Maccreted=(1.6±0.4)×10−4 M⊙. V1405 Cas provides counterexamples against five claims about CV evolution that have dominated since the 1980s. First, V1405 Cas has positive Ṗ, and this is contrary to the Magnetic Braking Model. Second, the ΔP is 20× too small to allow the system to fade into a hibernation state. Third, MWD is decreasing over time, as shown by Mejecta>Maccreted 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 Ṗ for 52 cataclysmic variables and 25 X-ray binaries that have together refuted all five claims.
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BibTeX
@misc{schaefer2026classical,
title = {{Classical Nova V1405 Cas Had $M_\rm ejecta$$>$$M_\rm accreted$ and so is Unlikely to be a Type Ia Supernova Progenitor}},
author = {Bradley E. Schaefer},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10990},
eprint = {2609.10990},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10990},
note = {CC BY 4.0},
}
RIS
TY - UNPB
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 - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.10990
UR - https://arxiv.org/abs/2609.10990
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 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_pre=0.1883919±0.0000018 days and P_post=0.1884043±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_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 CV evolution that have dominated since the 1980s. First, V1405 Cas has positive Ṗ, and this is contrary to the Magnetic Braking Model. Second, the ΔP 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 cataclysmic variables are universally declining in period from evolution. V1405 Cas is the latest of recent measures of ΔP and Ṗ for 52 cataclysmic variables and 25 X-ray binaries that have together refuted all five claims.
ER -