Abstract
ABSTRACT Many massive stars appear to undergo enhanced mass-loss during late stages of their evolution. In some cases, the ejected mass likely originates from non-terminal explosive outbursts, rather than continuous winds. Here we study the dependence of the ejecta mass, mej, on the energy budget E of an explosion deep within the star, using both analytical arguments and numerical hydrodynamics simulations. Focusing on polytropic stellar models, we find that for explosion energies smaller than the stellar binding energy, the ejected mass scales as $m_{\rm ej} \propto E^{\varepsilon _{\rm m}}$, where εm = 2.4–3.0 depending on the polytropic index. The loss of energy due to shock breakout emission near the stellar edge leads to the existence of a minimal mass-shedding explosion energy, corresponding to a minimal ejecta mass. For a wide range of progenitors, from Wolf–Rayet stars to red supergiants (RSGs), we find a similar limiting energy of $E_{\rm min} \approx 10^{46}\!-\!10^{47} \rm \, erg$, almost independent of the stellar radius. The corresponding minimal ejecta mass varies considerably across different progenitors, ranging from ${\sim } 10^{-8} \, \rm M_\odot$ in compact stars, up to ${\sim } 10^{-2} \, \rm M_\odot$ in RSGs. We discuss implications of our results for pre-supernova outbursts driven by wave heating, and complications caused by the non-constant opacity and adiabatic index of realistic stars.
Highlights
Massive stars appear to shed large amounts of mass during late stages of their evolution
Episodic eruptions, rather than continuous line-driven winds, are the dominant source of massloss from these stars (Smith 2014). This property of massive stars is a fundamental ingredient in a variety of astronomical phenomena – Type IIn and Ibn supernovae (SNe) are powered by the collision of core-collapse SN ejecta with dense circumstellar environments formed by earlier eruptive mass-loss; giant eruptions of luminous blue variables (LBVs) involve the ejection of large amounts of stellar material
The corresponding mass-loss is much smaller for compact stars due to their higher binding energy per unit mass, so a much larger energy budget is required for substantial mass ejection in those stars
Summary
Massive stars appear to shed large amounts of mass during late stages of their evolution. Kuriyama & Shigeyama (2020) carried out 1D-radiation hydrodynamical simulations in realistic stellar models to obtain the amount of ejecta mass and compute the light curve associated with pre-SN outbursts Another physical scenario involving a similar energy scale is the response of stellar envelopes to a pressure pulse arising from mass lost to neutrinos at the onset of core collapse. This mechanism has been first proposed by Nadezhin (1980), and was further investigated by Lovegrove & Woosley (2013) and Lovegrove, Woosley & Zhang (2017).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
