Chandra/HETG Doppler velocity measurements in stellar coronal sources.

Stellar coronal sources have been observed in the past not only for their astrophysical interest in the field of binary system evolution and interaction but also for their invaluable roles as benchmarks for plasma spectral models and as calibration sources for high resolution spectroscopic X-ray instruments. These include the gratings on-board Chandra and XMM-Newton , as well as the new generation of high resolution capable-detectors recently flown on-board XRISM and planned for the future also onboard the Athena and the LEM missions. In our previous paper exploiting Chandra /HETG observations of the prototypical coronal source Capella, it has been shown that the centroid energies of the many X-ray emission lines detected in the spectrum of this object change as a function of time due to the Doppler modulation within the binary. This is an effect that needs to be corrected while performing calibrations of high-resolution X-ray instruments. In this paper, we extend our previous work on Capella to other known stellar coronal sources that have been observed with the Chandra /HETG (11 objects in total). We measure in several objects clear trends in the velocity shifts along the orbit of the primary star, meaning that in these sources one of the two star components is largely dominating the high energy emission. In a number of systems the trend in the velocity shift is not obvious. This can be ascribed to the fact that both stellar components contribute significantly to the X-ray emission. [ABSTRACT FROM AUTHOR]