Classical-Nova Contribution to the Milky Way’s<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Al</mml:mi><mml:mprescripts /><mml:none /><mml:mn>26</mml:mn></mml:mmultiscripts></mml:math>Abundance: Exit Channel of the Key<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Al</mml:mi><mml:mprescripts /><mml:none /><mml:mn>25</mml:mn></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mi>Si</mml:mi><mml:mprescripts /><mml:none /><mml:mn>26</mml:mn></mml:mmultiscripts></mml:math>Resonance

Classical novae are expected to contribute to the 1809-keV Galactic γ-ray emission by producing its precursor 26Al, but the yield depends on the thermonuclear rate of the unmeasured 25Al(p,γ)26Si reaction. Using the β decay of 26P to populate the key J(π)=3(+) resonance in this reaction, we report the first evidence for the observation of its exit channel via a 1741.6±0.6(stat)±0.3(syst) keV primary γ ray, where the uncertainties are statistical and systematic, respectively. By combining the measured γ-ray energy and intensity with other experimental data on 26Si, we find the center-of-mass energy and strength of the resonance to be E(r)=414.9±0.6(stat)±0.3(syst)±0.6(lit.) keV and ωγ=23±6(stat)(-10)(+11)(lit.) meV, respectively, where the last uncertainties are from adopted literature data. We use hydrodynamic nova simulations to model 26Al production showing that these measurements effectively eliminate the dominant experimental nuclear-physics uncertainty and we estimate that novae may contribute up to 30% of the Galactic 26Al.

Classical-Nova Contribution to the Milky Way’sAl26Abundance: Exit Channel of the KeyAl25(p,γ)Si26Resonance Journal Articles