Thermonuclear fusion in dense stars

Electron screening, conductive cooling, and magnetic field effects

¹ CRAL (UMR CNRS No. 5574), École Normale Supérieure de Lyon, 69364 Lyon Cedex 07, France
e-mail: chabrier@ens-lyon.fr
² Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
e-mail: palex@astro.ioffe.ru
³ Isaac Newton Institute of Chile, St. Petersburg Branch, Russia
⁴ School of Physics, University of Exeter, Exeter EX4 4QL, UK

Received: 23 August 2011
Accepted: 3 December 2011

Abstract

We study the plasma correlation effects on nonresonant thermonuclear reactions of carbon and oxygen in the interiors of white dwarfs and liquid envelopes of neutron stars. We examine the effects of electron screening on thermodynamic enhancement of thermonuclear reactions in dense plasmas beyond the linear mixing rule. Using these improved enhancement factors, we calculate carbon and oxygen ignition curves in white dwarfs and neutron stars. The energy balance and ignition conditions in neutron star envelopes are evaluated, taking their detailed thermal structure into account. The result is compared to the simplified “one-zone model”, which is routinely used in the literature. We also consider the effect of strong magnetic fields on the ignition curves in the ocean of magnetars.