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Stardust grains recovered from meteorites provide highprecision\ud snapshots of the isotopic composition of the stellar\ud environment in which they formed1. Attributing their origin\ud to specific types of stars, however, often proves difficult.\ud Intermediate-mass stars of 4–8 solar masses are expected\ud to have contributed a large fraction of meteoritic stardust2,3.\ud Yet, no grains have been found with the characteristic isotopic\ud compositions expected for such stars4,5. This is a long-standing\ud puzzle, which points to serious gaps in our understanding of\ud the lifecycle of stars and dust in our Galaxy. Here we show that\ud the increased proton-capture rate of 17O reported by a recent\ud underground experiment6 leads to 17O/16O isotopic ratios that\ud match those observed in a population of stardust grainsfor\ud proton-burning temperatures of 60–80 MK. These temperatures\ud are achieved at the base of the convective envelope\ud during the late evolution of intermediate-mass stars of\ud 4–8 solar masses7–9, which reveals them as the most likely site\ud of origin of the grains. This result provides direct evidence\ud that these stars contributed to the dust inventory from which\ud the Solar System formed

The ^{17}O(p,α)^{14}N reaction plays a key role in various astrophysical scenarios, from asymptotic giant branch stars to classical novae. It affects the synthesis of rare isotopes such as ^{17}O and ^{18}F, which can provide constraints on astrophysical models. A new direct determination of the E_{R}=64.5  keV resonance strength performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) accelerator has led to the most accurate value to date ωγ=10.0±1.4_{stat}±0.7_{syst}  neV, thanks to a significant background reduction underground and generally improved experimental conditions. The (bare) proton partial width of the corresponding state at E_{x}=5672  keV in ^{18}F is Γ_{p}=35±5_{stat}±3_{syst}  neV. This width is about a factor of 2 higher than previously estimated, thus leading to a factor of 2 increase in the ^{17}O(p, α)^{14}N reaction rate at astrophysical temperatures relevant to shell hydrogen burning in red giant and asymptotic giant branch stars. The new rate implies lower ^{17}O/^{16}O ratios, with important implications on the interpretation of astrophysical observables from these stars.

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