1,531 research outputs found
Black Hole Formation and Explosion from Rapidly Rotating Very Massive Stars
We explore the formation process of a black hole (BH) through the
pair-instability collapse of a rotating Population III very massive star in
axisymmetric numerical relativity. As the initial condition, we employ a
progenitor star which is obtained by evolving a rapidly rotating zero-age main
sequence (ZAMS) star with mass until it reaches a pair instability
region. We find that for such rapidly rotating model, a fraction of the mass,
, forms a torus surrounding the remnant BH of mass and an outflow is driven by a hydrodynamical effect. We also
perform simulations, artificially reducing the initial angular velocity of the
progenitor star, and find that only a small or no torus is formed and no
outflow is driven. We discuss the possible evolution scenario of the remnant
torus for the rapidly rotating model by considering the viscous and
recombination effects and show that if the energy of erg is
injected from the torus to the envelope, the luminosity and timescale of the
explosion could be of the orders of erg/s and yrs, respectively. We
also point out the possibility for observing gravitational waves associated
with the BH formation for the rapidly rotating model by ground-based
gravitational-wave detectors.Comment: 19 pages, 16 figures, submitted to Ap
Neutrino-driven explosions of ultra-stripped type Ic supernovae generating binary neutron stars
We study explosion characteristics of ultra-stripped supernovae (SNe), which
are candidates of SNe generating binary neutron stars (NSs). As a first step,
we perform stellar evolutionary simulations of bare carbon-oxygen cores of mass
from 1.45 to 2.0 until the iron cores become unstable and start
collapsing. We then perform axisymmetric hydrodynamics simulations with
spectral neutrino transport using these stellar evolution outcomes as initial
conditions. All models exhibit successful explosions driven by neutrino
heating. The diagnostic explosion energy, ejecta mass, Ni mass, and NS mass are
typically erg, , , and
, which are compatible with observations of
rapidly-evolving and luminous transient such as SN 2005ek. We also find that
the ultra-stripped SN is a candidate for producing the secondary low-mass NS in
the observed compact binary NSs like PSR J0737-3039.Comment: 9 pages, 8 figures, 2 tables; accepted for publication in MNRA
Climatic factors affecting the tree-ring width of Betula ermanii at the timberline on Mount Norikura, central Japan
The original publication is available at www.springerlink.comArticleECOLOGICAL RESEARCH. 20(4):445-451(2005)journal articl
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