Non-standard s process in low metallicity massive rotating stars

By U. Frischknecht, R. Hirschi, Friedrich-Karl Thielemann. 2011

146 citations recorded by the source corpus.

Context. Rotation is known to affect the nucleosynthesis of light elements in massive stars, mainly by rotation-induced mixing. In particular, rotation boosts the primary nitrogen production. Models of rotating stars are able to reproduce the nitrogen observed in low-Z halo stars. Aims. Here we present the first grid of stellar models for rotating massive stars at low Z, where a full s-process network is used to study the impact of rotation-induced mixing on the nucleosynthesis of heavy elements. Methods. We used the Geneva stellar evolution code that includes an enlarged reaction network with nuclear species up to bismuth to calculate 25 M$_\odot$ models at three different Z and with different initial rotation rates. Results. First, we confirm that rotation-induced mixing leads to a production of primary $^{22}$Ne, which is the main neutron source for the s process in massive stars. Therefore rotation boosts the s process in massive stars at all Z. Second, the neutron-to-seed ratio increases with decreasing Z in models including rotation, which leads to the complete consumption of all iron seeds at Z 1% in mass fraction at all Z), which could open the door for an explosive neutron capture nucleosynthesis in the He-shell, with a primary neutron source.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ad809966a0cd14ce63069a770cc754c21be032a6

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Citations in the corpus

Chemical evolution with rotating massive star yields - I. The solar neighbourhood and the s-process elements (2018, background): “…yields: effects (i) to (iii) were studied with yields mainly from Hirschi (2007), while effect (iv) with yields from Frischnecht (2011, PhD Thesis), Frischknecht et al. (2012) and Frischknecht et al. (2016), where stars of different masses, metallicities and rotational velocities were considered.”
The Intermediate r-process in Core-collapse Supernovae Driven by the Magneto-rotational Instability (2016, background): “The existence of fast rotating massive stars at early galaxies is also supported by detection of Ba and La in metal-poor stars (Chiappini et al. 2011), which is explained by the enhanced s-process via strong rotational-induced mixing (Frischknecht et al. 2012; Nishimura et al. 2017).”
On the astrophysical robustness of the neutron star merger r-process (2012, background): “Given that its signature is less unique the second component might also be the result of a superposition from several sources (see e.g. Arcones & Montes (2011); Frischknecht et al. (2012)).”
NUGRID STELLAR DATA SET. I. STELLAR YIELDS FROM H TO BI FOR STARS WITH METALLICITIES Z = 0.02 and Z = 0.01 (2013, background): “…as astrophysical sources of the LEPP abundances, among them the s process in fast rotating massive stars at low metallicity (Pignatari et al. 2008; Frischknecht et al. 2012), the incomplete α−rich freezout in CCSN within the high-entropy neutrino winds produced during the formation of a neutron…”
GALACTIC CHEMICAL EVOLUTION AND SOLAR s-PROCESS ABUNDANCES: DEPENDENCE ON THE 13C-POCKET STRUCTURE (2014, background): “The weak component contributes to s isotopes up to A ∼ 90, and it takes place in massive stars during core He and convective shell C burning (see, e.g., Pignatari et al. 2010; Frischknecht et al. 2012).”
s-process production in rotating massive stars at solar and low metallicities (2015, methodology): “Although the 25 M models have already been discussed in Frischknecht et al. (2012), we provide more details about these models in this paper, and it is important to present models of all masses in a single paper.”