Hardena &Science

Two stars in uncomfortably close quarters. The larger has swollen past its Roche lobe; its outer atmosphere spills through the inner Lagrange point, arcs ballistically, and strikes the accretion disk of its white-dwarf neighbour — where the impact burns bright and, periodically, ignites.

DonorG2 V

CompanionWD

Period4.3 h

Separation0.86 R☉

Ṁ1.6e-9 M☉/yr

T_{disk inner}1e8 K

T_nova~10⁷ K

FPS · -- HOT SPOT · QUIET NOVA CYCLE · T-00:00 STREAM · 3800 p/s

Donor · G2 V Rho Coronae M = 0.78 M☉ · R = 0.94 R☉ · T = 5,800 K

White Dwarf · Primary Sirius B-sec M = 0.92 M☉ · R = 0.012 R☉ · T = 28,000 K

L1 Lagrange Saddle Point d ≈ 0.32 a

Accretion Disk Spiral Inbound 1e8 K inner → 5,000 K outer

Hot Spot · Impact Stream Shock T ≈ 10,000 K · brightest CV feature