Experimental determination of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">O</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>17</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>α</mml:mi></mml:mrow></mml:math>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">N</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>14</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">O</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>17</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi></mml:mrow></mml:math>)<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">F</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>18</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>reaction rates

The $^{17}\mathrm{O}$($p,\ensuremath{\alpha}$)$^{14}\mathrm{N}$ and $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ reactions are of major importance to hydrogen-burning nucleosynthesis in a number of different stellar sites. In particular, $^{17}\mathrm{O}$ and $^{18}\mathrm{F}$ nucleosynthesis in classical novae is strongly dependent on the thermonuclear rates of these two reactions. The previously estimated rate for $^{17}\mathrm{O}$($p,\ensuremath{\alpha}$)$^{14}\mathrm{N}$ carries very large uncertainties in the temperature range of classical novae ($T=0.01$--0.4 GK), whereas a recent measurement has reduced the uncertainty of the $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ rate. We report on the observation of a previously undiscovered resonance at ${E}_{c.m.}=183.3$ keV in the $^{17}\mathrm{O}$($p,\ensuremath{\alpha}$)$^{14}\mathrm{N}$ reaction, with a measured resonance strength $\ensuremath{\omega}{\ensuremath{\gamma}}_{p\ensuremath{\alpha}}=(1.6\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ eV. We studied in the same experiment the $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ reaction by an activation method, and the resonance strength was found to amount to $\ensuremath{\omega}{\ensuremath{\gamma}}_{p\ensuremath{\gamma}}=(2.2\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ eV. The excitation energy of the corresponding level in $^{18}\mathrm{F}$ was determined to be $5789.8\ifmmode\pm\else\textpm\fi{}0.3$ keV in a Doppler shift attenuation method measurement, which yielded a value of $\ensuremath{\tau}&lt;2.6$ fs for the level lifetime. The $^{17}\mathrm{O}$($p,\ensuremath{\alpha}$)$^{14}\mathrm{N}$ and $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ reaction rates were calculated using the measured resonance properties and reconsidering some previous analyses of the contributions of other levels or processes. The $^{17}\mathrm{O}$($p,\ensuremath{\alpha}$)$^{14}\mathrm{N}$ rate is now well established below $T=1.5$ GK, with uncertainties reduced by orders of magnitude in the temperature range $T=0.1$--0.4 GK. The uncertainty in the $^{17}\mathrm{O}$($p,\ensuremath{\gamma}$)$^{18}\mathrm{F}$ rate is somewhat larger because of remaining obscurities in the knowledge of the direct capture process. These new resonance properties have important consequences for $^{17}\mathrm{O}$ nucleosynthesis and \ensuremath{\gamma}-ray emission of classical novae.