s-Process Nucleosynthesis in Low-Metallicity Stars

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dc.creatorIwamoto, Nobuyuki
dc.creatorKajino, Toshitaka
dc.creatorMathews, Grant J.
dc.creatorFujimoto, Masayuki Y.
dc.creatorAoki, Wako
dc.date2002-03-12
dc.date.accessioned2026-07-07T02:03:05Z
dc.date.available2026-07-07T02:03:05Z
dc.descriptionWe have made a parametric study of s-process nucleosynthesis in the metal poor ([Fe/H]=-2.7) stars LP625-44 and LP706-7. We find that a high neutron exposure and a small overlap factor are necessary to fit the abundance pattern observed in these two metal-deficient stars, particularly the abundance ratios, Pb/Ba $\approx 1$ and Ba/Sr $\approx 10$. We have also constructed stellar models to better understand how such s-process conditions could arise. We have calculated a 2$M_\odot$ model star with metallicity [Fe/H]=-2.7 from the ZAMS up to AGB phase. We find that for such low-metallicity stars the He convective shell reaches the bottom of the overlying H-rich envelope at the second thermal pulse. Protons are then carried into the hotter He burning layers and $^{13}$C is formed as protons mix into the He shell. Subsequently, material in the H-flash driven convective zone experiences a high neutron exposure due to the $^{13}$C($α$, n) reaction. This results in a new neutron-capture s-process paradigm in which the abundances are characterized by only one neutron exposure. We suggest that this new s-process site may be a significant contributor to the s-process abundances in low-metallicity ([Fe/H] $\le -2.5$) stars.
dc.description4 pages, 4 figures, uses jnstcite.sty, nd2001_2.sty and article-nd2001_2.cls, J. Nucl. Sci. Technol., in press
dc.identifierhttps://arxiv.org/abs/astro-ph/0203180
dc.identifierhttp://arxiv.org/abs/astro-ph/0203180
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/4269
dc.subjectAstrophysics
dc.titles-Process Nucleosynthesis in Low-Metallicity Stars
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