The interaction of core-collapse supernova ejecta with a companion star
(11.09.2015)Zusammenfassung
The progenitors of many CCSNe are expected to be in binary systems. After the
SN explosion, the companion may suffer from mass stripping and be shock heated
as a result of the impact of the SN ejecta. If the binary system is disrupted,
the companion is ejected as a runaway or hypervelocity star. By performing a
series of 3D hydrodynamical simulations of the collision of SN ejecta with the
companion star, we investigate how CCSN explosions affect their companions. We
use the BEC code to construct the detailed companion structure at the time of
SN explosion. The impact of the SN blast wave on the companion is followed by
means of 3D SPH simulations using the Stellar GADGET code. For main-sequence
(MS) companions, we find that the amount of removed mass, impact velocity, and
chemical contamination of the companion that results from the impact of the SN
ejecta, strongly increases with decreasing binary separation and increasing
explosion energy. Their relationship can be approximately fitted by power laws,
which is consistent with the results obtained from impact simulations of SNe
Ia. However, we find that the impact velocity is sensitive to the momentum
profile of the outer SN ejecta and, in fact, may decrease with increasing
ejecta mass, depending on the modelling of the ejecta. Because most companions
to Ib/c CCSNe are in their MS phase at the moment of the explosion, combined
with the strongly decaying impact effects with increasing binary separation, we
argue that the majority of such SNe lead to inefficient mass stripping and
shock heating of the companion star following the impact of the ejecta. Our
simulations show that the impact effects of Ib/c SN ejecta on the structure of
MS companions, and thus their long term post-explosion evolution, is in general
not be dramatic. We find that at most 10\% of their mass is lost, and their
resulting impact velocities are less than 100 km/s.