  We have detected excess absorption in the emission cores of Ca II H & K
during transits of HD 189733b for the first time. Using observations of three
transits we investigate the origin of the absorption, which is also seen in
H{\alpha} and the Na I D lines. Applying differential spectrophotometry methods
to the Ca II H and Ca II K lines combined, using respective passband widths of
$\Delta\lambda$ = 0.4 & 0.6 \AA\ yields excess absorption of t$_d$ = 0.0074
$\pm$ 0.0044 (1.7$\sigma$; Transit 1) and 0.0214 +/- 0.0022 (9.8$\sigma$;
Transit 2). Similarly, we detect excess H{\alpha} absorption in a passband of
width $\Delta\lambda$ = 0.7 \AA, with t$_d$ = 0.0084 $\pm$ 0.0016 (5.2$\sigma$)
and 0.0121 $\pm$ 0.0012 (9.9$\sigma$). For both lines, Transit 2 is thus
significantly deeper. Combining all three transits for the Na I D lines yields
excess absorption of t$_d$ = 0.0041 $\pm$ 0.0006 (6.5$\sigma$). By considering
the time series observations of each line, we find that the excess apparent
absorption is best recovered in the stellar reference frame. These findings
lead us to postulate that the main contribution to the excess transit
absorption in the differential light curves arises because the normalising
continuum bands form in the photosphere, whereas the line cores contain a
chromospheric component. We can not rule out that part of the excess absorption
signature arises from the planetary atmosphere, but we present evidence which
casts doubt on recent claims to have detected wind motions in the planet's
atmosphere in these data.
