Seminario CAPA. Oscar Straniero (Ricerca del Instituto Nacional de Astrofísica de Italia, INAF)

"Not Too Big, Not Too Small: Bridging the Gap Between C-O White Dwarfs and 
Type IIP Supernova Progenitors. A challenge for underground nuclear astrophysics"

Oscar Straniero (Ricerca del Instituto Nacional de Astrofísica de Italia, INAF)

In stellar evolution literature, the fate of stars is traditionally framed as a dichotomy:
low-mass stars, which fail to ignite carbon after core hydrogen and helium burning, ascend
the Asymptotic Giant Branch (AGB), shed their envelopes via strong stellar winds, and end
their lives as cooling carbon-oxygen white dwarfs; and massive stars, which quiescently
burn carbon and subsequent advanced fuels (neon, oxygen, and silicon) up to the
formation of an iron-peak core that inevitably collapses as electron captures undermine its
degenerate support. However, between these two textbook regimes lies a delicate mass
transition window (8–10 M ) whose evolutionary pathways remain highly uncertain. Stars
in this intermediate range ignite carbon in degenerate conditions, leading to a rich diversity
of theoretical outcomes: massive hybrid or O-Ne white dwarfs, or core collapse via
electron-capture supernovae (EC-SNe). Furthermore, in interacting binary systems, these
massive white dwarfs can accrete material toward the Chandrasekhar limit, triggering
catastrophic transients such as Type Ia supernovae or accretion-induced collapse (AIC).
The boundary separating quiescent cooling from explosive death is exquisitely sensitive to
a key nuclear ingredient: the cross section of the 12C+12C fusion reaction. Currently,
experimental data at typical stellar carbon-burning energies (Ec.m. ~ 1–2 MeV) are affected
by severe uncertainties due to the Coulomb barrier suppression and potential molecular
resonances. To resolve this longstanding puzzle, the LUNA collaboration at the Laboratori
Nazionali del Gran Sasso (LNGS, Italy) is conducting a deep-underground direct
measurement campaign aimed at pushing the experimental frontier below the current 2.3
MeV threshold, shedding new light on the true nature of this fundamental astrophysical
process.
 

Fecha: jueves, 29 de octubre de 2026
Hora:   12:10 horas
Lugar: Seminario de Física Atómica, Molecular y Nuclear