The origins of neutron-capture elements in globular cluster M22

Introduction The chemical abundances of metal poor (MP) stars in globular clusters provide valuable information for constraining their evolutionary scenarios. Methods Using both main <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mi>r</mml:mi></mml:mrow></mml:math> -process and weak <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:mi>r</mml:mi></mml:mrow></mml:math> -process patterns, we fit the abundances of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:math> -poor stars in the globular cluster M22. Results and discussion The coefficients of the main and weak r -process components are nearly constant for the sample stars, including <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m8"><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:math> -rich stars. By considering the contribution of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:math> -process from low-mass AGB stars, the abundances of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m7"><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:math> -rich stars in M22 can also be fitted effectively. Furthermore, the increasing trend in the s-process component coefficients <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m9"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math> with increasing [Fe/H] suggests a gradual increase in the contribution from low-mass AGB stars.