LUNANOVA (grant agreement 101224374) is a recently awarded 14 M€ ERC Synergy Grant with a projected starting date in September 2026. 

At present, the properties and internal structure of the Sun can be inferred from solar neutrino experiments and helioseismology with a precision that significantly exceeds that achievable with state-of-the-art solar models. A major limitation in fully exploiting this wealth of experimental and observational data arises from degeneracies among model inputs, whereby different physical ingredients produce similar effects on observables, hindering a robust and unambiguous quantification of individual processes.

In this context, the nuclear cross sections of key hydrogen-burning reactions play a pivotal role, as they can be directly measured in laboratory experiments. LUNANOVA aims to eliminate nuclear reaction rates as a dominant source of uncertainty in the modeling of the Sun and solar-like stars by reducing their uncertainties to the 1% level. Precise measurements of solar neutrino fluxes will then enable the degeneracy between nuclear reaction rates and solar composition to be lifted. This, in turn, will allow an empirical determination of the solar radiative opacity profile, providing critical insight into atomic opacity calculations and yielding far-reaching implications for stellar modeling more broadly.

To achieve these objectives, a new dedicated underground ion accelerator, LUNANOVA for solar fusion, will be installed and operated at the Laboratori Nazionali del Gran Sasso in Italy. In combination with complementary measurements conducted at the Felsenkeller facility in Germany, the Bellotti Ion Beam Facility, and CIRCE in Italy, the resulting experimental data will be integrated into the development of next-generation models of the Sun and solar-like stars.

The sustained, long-term synergy between the LUNANOVA experimental program, complementary experimental and theoretical efforts worldwide, and advanced astrophysical modeling will provide the decisive breakthrough required to deepen our understanding of the Sun and to advance the field of nuclear astrophysics.

LUNANOVA is led by Alba Formicola (INFN, Italy), Daniel Bemmerer (HZDR, Germany), Gianluca Imbriani (University of Naples Federico II, Italy), and Aldo Serenelli (ICE-CSIC & IEEC).