21–26 Jun 2026
U. Ottawa - Learning Crossroads (CRX) Building
America/Toronto timezone
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(α,n) reactions and the origin of the first r-process peak

22 Jun 2026, 14:15
30m
U. Ottawa - Learning Crossroads (CRX) Building

U. Ottawa - Learning Crossroads (CRX) Building

100 Louis-Pasteur Private, Ottawa, ON K1N 9N3
Invited Speaker / Conférencier(ère) invité(e) Nuclear Physics / Physique nucléaire (DNP-DPN) (DNP) M2-6 Nuclear Astrophysics | Astrophysique nucléaire (DPN)

Speaker

Thanassis Psaltis (Saint Mary's University)

Description

The origin of the heavy elements of the first r-process peak, between strontium and silver, observed in Galactic halo stars (limited-r stars) remains an open question [1]. Neutrino-driven winds of explosive environments, either neutron- (weak r-process/α-process) or proton-rich (νp-process) present a viable option. In this talk, I will discuss how we can distinguish between different scenarios by constraining the nuclear physics uncertainties, particularly the (α,n) reaction rates in the weak r-process, and comparing nucleosynthesis models to the abundance patterns observed in limited-r stars [2]. I will discuss current experimental campaigns aimed at measuring key (α,n) reaction rates [3,4], and and how new, high-quality spectroscopic data from limited-r stars will provide essential constraints for the next generation of astrophysical models.

References
[1] A. Psaltis et al., Astrophys. J 935, 27 (2022).
[2] A. Psaltis et al., Astrophys. J 966, 11 (2024).
[3] M. Williams et al., Phys. Rev. Lett. 134, 112701 (2025).
[4] C. Fougères et al., Astrophys. J 983, 142 (2025).

Keyword-1 nuclear physics
Keyword-2 astrophysics

Author

Thanassis Psaltis (Saint Mary's University)

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