17th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun

Type: Poster

Topic: Evolved Stars and Hot-Cool Star Connection

Abstract
We have studied the HETGS spectra of Capella and the LETGS spectra of Procyon observed by the {\it Chandra X-ray Observatory} in order to identify L-shell transitions of the M-shell ions of iron, many of which also play an important role in the absorption features associated with spectra from AGNs. We have recently identified several Fe XVI L-shell transitions in spectra of Capella between 15 and 18 \AA\ [1]. With the help of laboratory measurements from the Lviermore EBIT-I electron beam ion trap and very accurate calculations, we have now also identified Fe XV lines in the HEG and MEG spectra of Capella. Our analyses of the LETGS spectra of Procyon show that Procyon provides an even better opportunity for studying such iron lines. Procyon is much cooler than Capella and the abundance of lower charge states of iron, i.e., of M-shell iron ions, is much higher. We show that the 15 to 18 \AA\ region of the Procyon spectrum contains lines from Fe XVII, Fe XVI, Fe XV, Fe XIV, and, possibly, Fe XIII. Work by the Lawrence Livermore National Laboratory was performed under the auspices of the Department of Energy under Contract No. DE-AC52-07NA-27344. This work was supported by NASA Astronomy and Physics Research and Analysis contract NNG07WF05I and Chandra Research Awards AR1-12006X and GO0-11031X. [1] Beiersdorfer, P., D\'iaz, F., \& Ishikawa, Y. 2012, Astrophys. J., 745, 167.