  Capella is the brightest chromospherically active binary in the sky, hosting
a cooler G8III giant (Aa) and an hotter G1III companion (Ab). The source has
been extensively observed in the X-rays in the past decades not only for its
astrophysical interest in the field of corona sources, but also for in-flight
calibrations of space-based X-ray instruments. In 2006, it was demonstrated
using Chandra/HETG observations that Aa is the main contributor to Capella's
X-ray emission, as the centroid energies of the emission lines are Doppler
shifted along the orbit of the G8III giant (an aspect that has to be taken in
consideration for calibration activities of X-ray instruments). In this paper,
we extend the previous analysis performed in 2006 by re-analyzing in an
homogeneous way all Chandra/HETG observations performed in the direction of
Capella. By doubling the amount of data available, we strengthened the
conclusion that Capella Aa is the dominant emitter in soft X-rays. We did not
find any evidence of a statistically significant contribution to this emission
by the Ab giant. Our findings are discussed also in light of the incoming
launch of the XRISM mission (spring 2023).
