Weak wind effects in CNO driven winds of hot first stars

¹ Ústav teoretické fyziky a astrofyziky PřF MU, 611 37 Brno, Czech Republic e-mail: krticka@physics.muni.cz
² Astronomický ústav, Akademie věd České republiky, 251 65 Ondřejov, Czech Republic

Received: 11 December 2009
Accepted: 3 March 2010

Abstract

Context. During the evolution of rotating first stars, which initially consisted of only hydrogen and helium, CNO elements may emerge to their surface. These stars may therefore have winds that are driven only by CNO elements.

Aims. We study weak wind effects (Gayley-Owocki heating and multicomponent effects) in stellar winds of first generation stars driven purely by CNO elements.

Methods. We apply our NLTE multicomponent models and hydrodynamical simulations.

Results. The multicomponent effects (frictional heating and decoupling) are important particularly for low metallicity winds, but they influence mass loss rate only if they cause decoupling for velocities lower than the escape velocity. The multicomponent effects also modify the feedback from first stars. As a result of the decoupling of radiatively accelerated metals from hydrogen and helium, the first low-energy cosmic ray particles are generated. We study the interaction of these particles with the interstellar medium concluding that these particles easily penetrate the interstellar medium of a given minihalo. We discuss the charging of the first stars by means of their winds.

Conclusions. Gayley-Owocki heating, frictional heating, and the decoupling of wind components occur in the winds of evolved low-metallicity stars and the solar metallicity main-sequence stars.