Laboratory measurements of Ca XIX dielectronic recombination satellites

We report measurements of the astrophysically predominant <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mi>K</a:mi> <a:mi>α</a:mi> </a:mrow> </a:math> emission from <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mi>Ca</b:mi> </b:math> XIX (He-like ion) and its satellite lines resonantly excited by dielectronic recombination (DR). We achieve an electron-energy resolution of 8 eV in a cryogenic electron beam ion trap, and determine the energies of the exciting electrons and the emitted photons up to the ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mi>n</c:mi> <c:mo>≤</c:mo> <c:mn>8</c:mn> </c:mrow> </c:math> ) manifold with 0.05 and 0.1% respective uncertainties. For the satellites, energies agree very well with our predictions using the Flexible Atomic Code () and previous state-of-the-art calculations. Our calculations also agree with our experimental direct excitation cross sections for <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mi>K</d:mi> <d:mi>α</d:mi> </d:mrow> </d:math> within their 10% uncertainty. We extract DR coefficient rates from our calculations and find good agreement with values tabulated in the OPEN-ADAS database. Moreover, we compare synthetic spectra, incorporating the DR atomic data benchmarked in the present work, with recent x-ray imaging and spectroscopy mission observations. This comparison highlights the contributions of DR satellites to the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mi>Ca</e:mi> </e:math> main lines.