5 Ca  II H&K spectroscopy

In 1999 we have acquired a spectrum of HR 7428 in the blue-violet region. The Ca  II H & K line region is shown in Fig. 7.

Figure 7: Ca II H & K lines in a spectrum of HR 7428 acquired in 1999.

The chromospheric emission core is evident both in H and K lines. These emission components are broad, as expected from the Wilson-Bappu effect for a low gravity star (Elgarøy et al. 1997).

The absorption wings of the Ca  II H line are deeper than those of the K line, due to the broad and stron hydrogen H$\epsilon$ absorption line of the hot component that is superimposed on the Ca  II H line. Furthermore, the asymmetry seen into the K line core is probably due to the sharp K line absorption of the hot component spectrum that is blue-shifted at the time of the observation ( $\phi\,=\,0.323$).

The observed profiles are similar to those observed by Fernández-Figueroa et al. (1994), but in their spectrum the K-line core absorption is slightly red-shifted.