KQ Pup (HD 60414) is a well known long period spectroscopic binary of the VV Cephei type with a M1-2Iab primary and a B0V companion.
We observed the NIR of KQ Pup at high resolution in December 1990 and in
January 1995, when the orbital phase 
of the system was 0.69 and 0.84,
respectively.
Both spectra, reproduced in Fig. 2, present a rich M-type absorption
spectrum and the fluorescence
Fe II 1.00 
m line in emission.
The photospheric lines are narrower than in the similar spectral type
star 
Ori suggesting a larger surface macroturbulence for the latter.
The measurement of the Fe II emission is difficult because of the
line crowding.
In order to overcome this effect we used the spectrum of the K4-supergiant
Aur taken with the same instrumental setup, which appears
similar in line depth and especially width to that of KQ Pup.
After having scaled all the spectra to the same velocity and normalized them to
the continuum, we subtracted Aur to KQ Puppis.
The Fe II 1.00 m dereddened line fluxes in the two epochs are
of 8.0 and 7.5 10-12 erg cm-2 s-1, respectively. These values are
about three times larger with respect to the theoretical flux of
2.5 10-12 erg cm-2 s-1, computed according to the Self-Absortion-Curve
analysis of the Fe II lines in the 1979 UV spectrum of KQ Pup made by
Muratorio et al. (1992).
This difference should be accounted for by the anomalous strength of the
high excitation Fe II emission lines as noted by Muratorio et al. (1992).
It might also be at least partly due to the gradual increase of the line
‰emission when the KQ Pup system is approaching the periastron
(Cowley 1965).
The HRV of the M-component was in both epochs in good agreement with the
velocity curve reproduced by Cowley (1965). On the other hand, the behaviour
of the Fe II 1.00 m line was similar to that observed in the Fe II emission lines
during 1969-1983, i.e. radial velocity systematically more negative than that
of the M-star, and smaller amplitude of the radial velocity curve
(Rossi et al. 1992).
In 1995 we obtained a high resolution spectrum in the H
region, which is plotted in Fig. 1 (click here) normalised to the continuum
and compared with that one of the same resolution
taken in 1984 with the ESO CAT-CES (
).
While the M spectrum shows no change, the H profile
largely varied between the two epochs with an increase of the emission
intensity and a shift of the relative positions
with respect to the M-spectrum.
This last effect is probably due to the strong redshift of the
absorption core.
In the red wing of the emission a plateau extends to +148 km s-1\
in 1984
and to +132 km s-1 in 1995; the difference in velocity
is the same as for the M spectrum, confirming the hypothesis discussed by
Rossi et al. (1992), that the plateau should be attributed
to the stellar TiO 
(0,1) band absorption at 656.4 nm.
In January 1995 we have also obtained intermediate resolution blue
spectra which we compared with the Coudé spectrograms (with nearly the same
resolution) described in the Atlas of Altamore et al. (1992).
The Balmer lines are weaker than in December 1969 (
),
very similar in shape and strength to those of March 1979 (
).
and stronger than in February 1983 (
).
Similar behaviour was displayed by the other emission lines.
The picture arising from these observations, which span almost
an entire cycle of the orbital motion, indicates that the emission
spectrum of the KQ Pup system faded after the last periastron passage (1972),
and now, as the next pariastron passage (1999) is approaching,
it is brightening again.