Capella is an interesting object to observe at X-ray wavelengths at
high resolution for several reasons:

First of all, observations in the ultraviolet (Dupree, et al,
ApJ,418,L41,1993) suggest strong emission over a narrow temperature
region near 6.3e6 K, very unlike the sun.

Secondly, previous X-ray observations of Capella are generally fit
with two-temperature models, but the best-fit parameters vary widely
(i.e., derived temperatures and metal abundances vary considerably).
These variations could be artifacts of the fits themselves, or they
could reflect deficiencies of the theoretical modeling.

The high resolution spectrum provided by Chandra's HETG resolves
individual X-ray lines, which are direct probes to answer the
questions of temperature and abundance. These observations will help
answer the question of why stars have any hot material, and why stars
with coronae differ from one another.