Mass loss of massive stars near the Eddington luminosity by core neutrino emission shortly before their explosion

¹ Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
e-mail: moriyatk@astro.uni-bonn.de
² Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo, 113-033 Tokyo, Japan

Received: 6 November 2013
Accepted: 11 March 2014

Abstract

We present a novel mechanism for enhancing the mass-loss rates of massive stars shortly before their explosion. The neutrino luminosities of the stellar core of massive stars increase as they get closer to the time of the core collapse. As emitted neutrinos escape freely from the core, the core mass is significantly reduced when the neutrino luminosity is high. If a star is near the Eddington luminosity when the neutrino luminosity is high, the star can exceed the Eddington luminosity because of the core neutrino mass loss. We suggest that the stellar surface mass-loss rates due to the core neutrino emission can be higher than 10^-4 M_⊙ yr^-1 from ~1 year before the core collapse. The mass-loss rates can exceed 10^-2 M_⊙ yr^-1 ~ 10 days before the core collapse. This mass-loss mechanism may be able to explain the enhanced mass loss observed in some supernova progenitors shortly before their explosion. Even if the star is not close enough to the Eddington luminosity to enhance the mass loss, the star can still expand because of the reduced gravitational force. This mechanism can be activated in Wolf-Rayet stars, and it can create the hydrogen-poor, as well as hydrogen-rich, dense circumstellar media observed in some supernovae.