Effects of a new triple-α reaction on x-ray bursts of a helium-accreting neutron star

Abstract

The effects of a new triple-a reaction (OKK) rate on a helium flash of a helium-accreting neutron star in a binary system have been investigated. Since ignition points determine the properties of a thermonuclear flash of type I X-ray bursts, we examine the cases of different accretion rates, dM/dt ( .M ), of helium from 3× 10 -10M ⊙yr-1 to 3 × 10 -8M ⊙yr -1, which could cover the observed accretion rates. We find that, at low accretion rates, nuclear burning occurs at the helium layers of rather low densities. As a consequence, helium deflagration would be triggered at accretion rate lower than M ≃ 3 × 10- 8M ⊙yr-1. We find that the OKK rate is consistent with the available observations of X-ray bursts on a helium-accreting neutron star. We advocate that the OKK rate is better than the previous rate for the astrophysical phenomena of X-ray burst due to helium accretion.