2024/12/23 by Schaefer, Bradley E. · 4 citations
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2412.17286
V445 Puppis is the only known example of a helium nova, where a layer of helium-rich gas accretes onto the surface of a white dwarf in a cataclysmic variable, with runaway helium burning making for the nova event. Speculatively, helium nova can provide one path to produce a Type Ia supernova (SNIa), within the larger framework of single-degenerate models. Relatively little has been known about V445 Pup, with this work reporting the discovery of the orbital period near 1.87 days. The companion star is 2.65±0.35 R\odot in radius as an evolved giant star stripped of its outer hydrogen envelope. The orbital period immediately before the 2000 eruption was P\rm pre=1.871843±0.000014 days, with a steady period change of (-0.17±0.06)×10-8 from 1896--1995. The period immediately after the nova eruption was P\rm post=1.873593±0.000034 days, with a P of (-4.7±0.5)×10-8. The fractional orbital period change (ΔP/P) is +935±27 ppm. This restricts the mass of the gases ejected in the nova eruption to be ≫0.001M\odot, and much greater than the mass accreted to trigger the nova. So the white dwarf is losing mass over each eruption cycle, and will not become a SNIa. Further, for V445 Pup and helium novae in general, I collect observations from 136 normal SNIa, for which any giant or sub-giant companion star would have been detected, yet zero companions are found. This is an independent proof that V445 Pup and helium novae are not SNIa progenitors.