2020A&A...639A.126C -
Astronomy and Astrophysics, volume 639A, 126-126 (2020/7-1)
A strong neutron burst in jet-like supernovae of spinstars.
CHOPLIN A., TOMINAGA N. and MEYER B.S.
Abstract (from CDS):
Context. Some metal-poor stars have abundance patterns, which are midway between the slow (s) and rapid (r) neutron capture processes. Aims. We show that the helium shell of a fast rotating massive star experiencing a jet-like explosion undergoes two efficient neutron capture processes: one during stellar evolution and one during the explosion. It eventually provides a material whose chemical composition is midway between the s- and r-process. Methods. A low metallicity 40M☉ model with an initial rotational velocity of ∼700km/s was computed from birth to pre-supernova with an extended nuclear network following the slow neutron capture process. A two-dimensional hydrodynamic relativistic code was used to model a E=1052erg relativistic jet-like explosion hitting the stellar mantle. The jet-induced nucleosynthesis was calculated in post-processing with an optimised network of 1812 nuclei. Results. During the star's life, heavy elements from 30≤Z≤82 are produced thanks to an efficient s-process, which is boosted by rotation. At the end of evolution, the helium shell is largely enriched in trans-iron elements and in (unburnt) 22Ne, whose abundance is ∼20 times higher than in a non-rotating model. During the explosion, the jet heats the helium shell up to ∼1.5GK. It efficiently activates (α, n) reactions, such as 22Ne(α, n), and leads to a strong n-process with neutron densities of ∼1019-1020cm–3 during 0.1s. This has the effect of shifting the s-process pattern, which was built during stellar evolution, towards heavier elements (e.g. Eu). The resulting chemical pattern is consistent with the abundances of the carbon-enhanced metal-poor r/s star CS29528-028, provided the ejecta of the jet model is not homogeneously mixed. Conclusions. The helium burning zones of rotating massive stars experience an efficient s-process during the evolution followed by an efficient n-process during a jet-like explosion. This is a new astrophysical site which can explain at least some of the metal-poor stars showing abundance patterns midway between the s- and r-process.
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Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
References (21 between 1850 and 2024) (Total 21)
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